@article{bedir_kadian_shukla_gunduz_narayan_2024, title={Additive manufacturing of microneedles for sensing and drug delivery}, volume={7}, ISSN={["1744-7593"]}, DOI={10.1080/17425247.2024.2384696}, abstractNote={Introduction Microneedles (MNs) are miniaturized, painless, and minimally invasive platforms that have attracted significant attention over recent decades across multiple fields, such as drug delivery, disease monitoring, disease diagnosis, and cosmetics. Several manufacturing methods have been employed to create MNs; however, these approaches come with drawbacks related to complicated, costly, and time-consuming fabrication processes. In this context, employing additive manufacturing (AM) technology for MN fabrication allows for the quick production of intricate MN prototypes with exceptional precision, providing the flexibility to customize MNs according to the desired shape and dimensions. Furthermore, AM demonstrates significant promise in the fabrication of sophisticated transdermal drug delivery systems and medical devices through the integration of MNs with various technologies.}, journal={EXPERT OPINION ON DRUG DELIVERY}, author={Bedir, Tuba and Kadian, Sachin and Shukla, Shubhangi and Gunduz, Oguzhan and Narayan, Roger}, year={2024}, month={Jul} }
 @article{keerthanaa_panicker_narayan_kotagiri_2024, title={Biopolymer-protected graphene-Fe<sub>3</sub>O<sub>4</sub> nanocomposite based wearable microneedle sensor: toward real-time continuous monitoring of dopamine}, volume={14}, ISSN={["2046-2069"]}, DOI={10.1039/d4ra00110a}, abstractNote={Neurological disorders can occur in the human body as a result of nano-level variations in the neurotransmitter levels.}, number={10}, journal={RSC ADVANCES}, author={Keerthanaa, M. R. and Panicker, Lakshmi R. and Narayan, Roger and Kotagiri, Yugender Goud}, year={2024}, month={Feb}, pages={7131–7141} }
 @article{kadian_kumari_sahoo_shukla_narayan_2024, title={Machine learning enabled microneedle-based colorimetric pH sensing patch for wound health monitoring and meat spoilage detection}, volume={200}, ISSN={["1095-9149"]}, url={https://doi.org/10.1016/j.microc.2024.110350}, DOI={10.1016/j.microc.2024.110350}, abstractNote={Since pH can alter the biological functions, level of nutrients, wound healing process, and the behavior of chemicals, various healthcare and food industries are showing increased interest in manufacturing low-cost optical pH sensors for meat spoilage detection and wound health monitoring. To meet this demand, we have developed a simple and low-cost machine learning-enabled microneedle-based colorimetric pH sensing patch that can be used for food quality and wound health monitoring applications. The 3D–printed ultrasharp open side channel microneedle array facilitated the autonomous fluid extraction and transportation via surface tension for colorimetric pH sensing. Further, to predict the exact pH value against the obtained color on the pH-test strip, a machine learning model was prepared using experimentally collected different color images obtained from a known pH solution. Furthermore, to make the device user-friendly for older individuals and color-blind individuals, a simple and smartphone-enabled web application was prepared using the developed machine learning model. The proof-of-concept study of the developed patch was demonstrated by determining the pH of real meat samples before and after spoilage and detecting pH in two different skin-mimicking in vitro models (phantom gel and parafilm tape) using a smartphone. The analytical results demonstrated that the developed machine learning-enabled microneedle-based colorimetric pH sensing patch has excellent potential for wound health and food safety applications.}, journal={MICROCHEMICAL JOURNAL}, author={Kadian, Sachin and Kumari, Pratima and Sahoo, Siba Sundar and Shukla, Shubhangi and Narayan, Roger J.}, year={2024}, month={May} }
 @article{kadian_sahoo_kumari_narayan_2024, title={Machine learning enabled onsite electrochemical detection of lidocaine using a microneedle array integrated screen printed electrode}, volume={475}, ISSN={["1873-3859"]}, url={https://doi.org/10.1016/j.electacta.2023.143664}, DOI={10.1016/j.electacta.2023.143664}, abstractNote={Despite several advantageous uses of lidocaine patches to overcome discomfort and pain in various clinical settings, overdosage of this drug can cause unwanted side effects on the cardiovascular and central nervous system, which can lead to life-threatening conditions. Therefore, the development of a rapid, sensitive, and user-friendly point-of-care device for onsite lidocaine detection is of great clinical importance. To address this issue, we have developed a machine learning enabled wireless microneedle array integrated screen-printed electrode-based electrochemical point-of-care device for rapid and effective detection of lidocaine. The fabricated device utilizes novel ultra-sharp microneedles arrays having a reservoir in its base, which are designed to collect the interstitial fluid through open side channels, and graphene-modified screen-printed carbon electrodes for the electrochemical detection of lidocaine. Under optimal conditions, the developed sensor exhibited high sensitivity and good selectivity towards lidocaine along with a linear current response over the detection range from 1-120 µM with the lowest detection limit of 0.13 µM. In addition, to make the device user friendly, a machine learning model was developed using experimental sensing data to predict the lidocaine concentration and further deployed to prepare a web application for digital visualization of lidocaine concentration.}, journal={ELECTROCHIMICA ACTA}, author={Kadian, Sachin and Sahoo, Siba Sundar and Kumari, Pratima and Narayan, Roger J.}, year={2024}, month={Jan} }
 @article{shukla_khanna_sahoo_joshi_narayan_2024, title={Nanomaterial-Coated Carbon-Fiber-Based Multicontact Array Sensors for In Vitro Monitoring of Serotonin Levels}, volume={7}, ISSN={["2576-6422"]}, url={http://dx.doi.org/10.1021/acsabm.3c01089}, DOI={10.1021/acsabm.3c01089}, abstractNote={In this study, we demonstrated the fabrication of multicontact hierarchical probes for the in vitro detection of serotonin levels. The basic three-dimensional (3D) bendable prototypes with 3 (C1), 6 (C2), or 9 (C3) contact surfaces were printed from polymeric resin via the digital light processing (DLP) technique. We chose ultrasonicated carbon fiber strands to transform these designs into multicontact carbon fiber electrodes (MCCFEs). The exposed carbon fiber (CF) surfaces were modified with aminopropyl alkoxysilane (APTMS), followed by the subsequent loading of palladium nanoclusters (PdNPs) to build active recording sites. CF functionalization with PdNPs was achieved by the wet chemical reduction of Pd(II) to Pd(0). The MCCFE configurations demonstrated an enhancement in the electroactive surface area and an improved voltammetric response toward 5-HT oxidation by increasing the points of the contacts (i.e., from C1 to C3). These MCCFEs are comparable to 3D-protruding electrodes as they can enable multipoint analyte detection. Along with the electrode patterns, morphological irregularities associated with both Pd-doped and undoped CFs supported the creation of proximal diffusion layers for facile mass transfer. Low detection limits of 0.8-10 nM over a wide concentration range, from 0.005 nM to 1 mM, were demonstrated. The MCCFE sensors had a relatively low standard deviation value of ∼2%. This type of sensitive and cost-effective electrochemical sensor may prove useful for collecting electrical impulses and long-term monitoring of 5-HT in vivo in addition to in vitro testing.}, number={1}, journal={ACS APPLIED BIO MATERIALS}, author={Shukla, Shubhangi and Khanna, Sumeer and Sahoo, Siba and Joshi, Naveen and Narayan, Roger}, year={2024}, month={Jan}, pages={472–484} }
 @article{yang_liu_skoog_narayan_2024, title={Physico-chemical properties and cytotoxicity of gelatin methacryloyl crosslinked with nanoparticle photoinitiator}, ISSN={["2044-5326"]}, DOI={10.1557/s43578-024-01369-7}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Yang, Kai-Hung and Liu, Yizhong and Skoog, Shelby A. and Narayan, Roger J.}, year={2024}, month={Jun} }
 @article{joshi_shukla_khosla_vanderwal_stafslien_narayan_narayan_2024, title={Q-carbon as an emergent surface coating material for antimicrobial applications}, volume={791}, ISSN={["1879-2731"]}, url={https://doi.org/10.1016/j.tsf.2024.140227}, DOI={10.1016/j.tsf.2024.140227}, abstractNote={Q-carbon, an allotrope of carbon, exhibits exciting functional properties and robust mechanical strength. We propose that the surface of the Q-carbon can be functionalized by doping it with silicon to enhance its performance as a potential implant material. As such, a coating of silicon-doped Q-carbon (Si-Q-carbon) is shown to minimize the formation of biofilm, thus reducing the risk of microbial infection. We report the formation of Si-Q-carbon coatings of varied thicknesses (10nm and 20nm) through the plasma-enhanced chemical vapor deposition technique. The surface composition and the bonding characteristics of the thin films were evaluated by Raman spectroscopy, XPS, and EELS studies, which showed that the thinnest sample (10nm) has a high sp3 content of ∼85%. Furthermore, wettability and surface energy calculations were undertaken to investigate the surface characteristics of the coatings. The 10nm sample was found to be more hydrophilic with a water contact angle of 75.3° (± 0.6°). The antibacterial activity of Si-Q-carbon coatings was investigated using a Staphylococcus epidermidis agar plating technique, and the adhesion of bacteria was explained in terms of the surface properties of the thin films. We demonstrate that the Si-Q-carbon coating with the highest sp3 content is hydrophilic and showed a 57% reduction in adhered biofilm relative to a glass control. We envisage the potential application of Q-carbon in arthroplasty devices with enhanced mechanical strength and resistance to periprosthetic joint infections.}, journal={THIN SOLID FILMS}, author={Joshi, Naveen and Shukla, Shubhangi and Khosla, Nayna and Vanderwal, Lyndsi and Stafslien, Shane and Narayan, Jagdish and Narayan, Roger J.}, year={2024}, month={Feb} }
 @article{tiwari_gupta_narayan_pandey_2023, title={A whole cell fluorescence quenching-based approach for the investigation of polyethyleneimine functionalized silver nanoparticles interaction with Candida albicans}, volume={14}, ISSN={["1664-302X"]}, DOI={10.3389/fmicb.2023.1131122}, abstractNote={The antimicrobial activity of metal nanoparticles can be considered a two-step process. In the first step, nanoparticles interact with the cell surface; the second step involves the implementation of the microbicidal processes. Silver nanoparticles have been widely explored for their antimicrobial activity against many pathogens. The interaction dynamics of functionalized silver nanoparticles at the biological interface must be better understood to develop surface-tuned biocompatible nanomaterial-containing formulations with selective antimicrobial activity. Herein, this study used the intrinsic fluorescence of whole C. albicans cells as a molecular probe to understand the cell surface interaction dynamics of polyethyleneimine-functionalized silver nanoparticles and antifungal mechanism of the same. The results demonstrated that synthesized PEI-f-Ag-NPs were ~ 5.6 ± 1.2 nm in size and exhibited a crystalline structure. Furthermore, the recorded zeta potential (+18.2 mV) was associated with the stability of NPS and shown a strong electrostatic interaction tendency between the negatively charged cell surface. Thus, rapid killing kinetics was observed, with a remarkably low MIC value of 5 μg/mL. PEI-f-Ag-NPs quenched the intrinsic fluorescence of C. albicans cells with increasing incubation time and concentration and have shown saturation effect within 120 min. The calculated binding constant (Kb = 1 × 105 M−1, n = 1.01) indicated strong binding tendency of PEI-f-Ag-NPs with C. albicans surface. It should also be noted that the silver nanoparticles interacted more selectively with the tyrosine-rich proteins in the fungal cell. However, calcofluor white fluorescence quenching showed non-specific binding on the cell surface. Thus, the antifungal mechanisms of PEI-f-Ag-NPs were observed as reactive oxygen species (ROS) overproduction and cell wall pit formation. This study demonstrated the utility of fluorescence spectroscopy for qualitative analysis of polyethyleneimine-functionalized silver nanoparticle interaction/binding with C. albicans cell surface biomolecules. Although, a quantitative approach is needed to better understand the interaction dynamics in order to formulate selective surface tuned nanoparticle for selective antifungal activity.}, journal={FRONTIERS IN MICROBIOLOGY}, author={Tiwari, Atul Kumar and Gupta, Munesh Kumar and Narayan, Roger J. J. and Pandey, Prem C. C.}, year={2023}, month={Feb} }
 @article{pandey_verma_pandey_narayan_2023, title={Bone tissue engineering application of 3-aminopropyltrimethoxysilane functionalized Au/Ag bimetallic nanoparticles incorporated hydroxyapatite bioceramic}, ISSN={["2044-5326"]}, DOI={10.1557/s43578-023-01132-4}, abstractNote={Despite having excellent osteoconductivity and biocompatibility, hydroxyapatite (HA) exhibits inadequate mechanical properties and bacterial susceptibility, which limits its medical applications. The present study aims to fabricate 3-aminopropyltrimethoxysilane (3-APTMS) functionalized gold (Au)-silver (Ag) nanoparticles incorporated in hydroxyapatite bioceramics to overcome this limitation. Thermogravimetric analysis (TGA), X-Ray diffraction, and scanning electron microscopy were carried out to understand the physical and chemical characteristics of the material. The maximum values of fracture toughness, hardness, compressive and flexural strength were measured for HA-10 Au/Ag NPs. Both quantitative and qualitative analyses of antibacterial behavior revealed that the adhesion of gram-positive (Staphylococcu aureus) and gram-negative (Eschericia coli) bacterial cells were reduced significantly after the incorporation of Au/Ag NPs as compared with the HA control. In addition, the effect of Au/Ag NPs incorporation on the cellular response was observed for the MG63 cell line. Both the quantitative and qualitative results indicate significantly enhanced cell proliferation with the incorporation of Au/Ag NPs as compared to HA. The addition of Au/Ag NPs in HA provides a material with appropriate mechanical, antibacterial, and cellular responses for further consideration.}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Pandey, Maneesha and Verma, Alok Singh and Pandey, P. C. and Narayan, Roger J.}, year={2023}, month={Aug} }
 @misc{shukla_jakowski_kadian_narayan_2023, title={Computational approaches to delivery of anticancer drugs with multidimensional nanomaterials}, volume={21}, ISSN={["2001-0370"]}, DOI={10.1016/j.csbj.2023.08.010}, abstractNote={Functionalized nanotubes (NTs), nanosheets, nanorods, and porous organometallic scaffolds are potential in vivo carriers for cancer therapeutics. Precise delivery through these agents depends on factors like hydrophobicity, payload capacity, bulk/surface adsorption, orientation of molecules inside the host matrix, bonding, and nonbonding interactions. Herein, we summarize advances in simulation techniques, which are extremely valuable in initial geometry optimization and evaluation of the loading and unloading behavior of encapsulated drug molecules. Computational methods broadly involve the use of quantum and classical mechanics for studying the behavior of molecular properties. Combining theoretical processes with experimental techniques, such as X-ray crystallography, NMR spectroscopy, and bioassays, can provide a more comprehensive understanding of the structure and function of biological molecules. This integrated approach has led to numerous breakthroughs in drug discovery, enzyme design, and the study of complex biological processes. This short review provides an overview of results and challenges described from erstwhile investigations on the molecular interaction of anticancer drugs with nanocarriers of different aspect ratios.}, journal={COMPUTATIONAL AND STRUCTURAL BIOTECHNOLOGY JOURNAL}, author={Shukla, Shubhangi and Jakowski, Jacek and Kadian, Sachin and Narayan, Roger J.}, year={2023}, pages={4149–4158} }
 @article{kummari_panicker_gobi_narayan_kotagiri_2023, title={Electrochemical Strip Sensor Based on a Silver Nanoparticle-Embedded Conducting Polymer for Sensitive In Vitro Detection of an Antiviral Drug}, ISSN={["2574-0970"]}, DOI={10.1021/acsanm.3c02080}, abstractNote={A straightforward and disposable electrochemical sensor was developed by the direct electrodeposition of silver nanoparticles (AgNPs) on a conducting polymer and an acid-functionalized carbon nanotube-modified screen-printed carbon electrode (f-CNT/SPCE) for the detection of the antiviral drug valganciclovir (VGC). A scaffold layer of the conducting polymer 2,6-diaminopyridine (p-DAP) was electrodeposited on an f-CNT/SPCE surface via a potentiodynamic polarization method. Later, homogeneous deposition of AgNPs was carried out on the polymer-modified scaffold layers. The electrode activities related to the concentration of the polymer substrate and the AgNP precursor were systematically optimized. The electrochemical oxidation of VGC by SPCE/f-CNT/p-DAP-AgNPs was investigated by square-wave voltammetry. The modified sensor exhibited an attractive electroanalytical performance toward VGC with high sensitivity (nanomolar range), selectivity (in the presence of uric acid and dopamine), reproducibility, and long-term storage stability. Potential real-world applications of the modified screen-printed sensor were demonstrated using artificial urine/serum and industrial water samples. The straightforward design and attractive analytical performance of the conductive polymer-embedded AgNP -modified screen-printed sensor suggest considerable promise for use of this sensor in the point-of-care screening of antiviral drugs. The sensor strip would also be useful in the screening of antiviral drugs in industrial (quality control) and environmental (industry effluents) applications.}, journal={ACS APPLIED NANO MATERIALS}, author={Kummari, Shekher and Panicker, Lakshmi and Gobi, K. Vengatajalabathy and Narayan, Roger and Kotagiri, Yugender Goud}, year={2023}, month={Jun} }
 @article{li_kadian_mishra_huang_zhou_liu_wang_narayan_zhu_2023, title={Electrochemical detection of cholesterol in human biofluid using microneedle sensor}, volume={5}, ISSN={["2050-7518"]}, DOI={10.1039/d2tb02142k}, abstractNote={The development of a straightforward, economical, portable, and highly sensitive sensing platform for the rapid detection of cholesterol is desirable for the early diagnosis of several pathologic conditions.}, journal={JOURNAL OF MATERIALS CHEMISTRY B}, author={Li, Zhanhong and Kadian, Sachin and Mishra, Rupesh K. K. and Huang, Tiangang and Zhou, Chen and Liu, Shuyuan and Wang, Zifeng and Narayan, Roger and Zhu, Zhigang}, year={2023}, month={May} }
 @article{khosla_narayan_narayan_2023, title={Laser-assisted formation of 3c-SiC and continuous diamond growth using Si-Q carbon on (100) silicon}, volume={12}, ISSN={["2044-5326"]}, DOI={10.1557/s43578-023-01264-7}, abstractNote={The formation of 3c-SiC is of interest due to potential applications in the semiconductor industry; however, there are difficulties in obtaining 3c-SiC by conventional methods. Being a metastable phase, non-equilibrium growth conditions are favorable in the growth process. This paper reports the formation of nano-sized 3c-SiC by nanosecond laser annealing of Si–Q-carbon layers on the silicon (100), which is confirmed by its characteristic LO and TO peaks in the Raman spectra. We also show that the traditional HFCVD technique results in the 6H-polytype instead, as confirmed by SEM, Raman spectroscopy, and EBSD. Further, we investigate the role of these phases on the nucleation of heteroepitaxial diamond on a Si (100) substrate. We show that these phases as interlayers enhance the diamond growth significantly. The HRSTEM studies were performed to understand the interfacial structure and phase responsible for high diamond nucleation. These findings are significant for 3c-SiC and diamond electronics applications. Graphical abstract}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Khosla, Nayna and Narayan, Jagdish and Narayan, Roger}, year={2023}, month={Dec} }
 @article{tabish_thorat_narayan_2023, title={Mechanical behaviour of nitric oxide releasing polymers for cardiovascular bypass grafts}, volume={176}, ISSN={["1872-7743"]}, DOI={10.1016/j.mechmat.2022.104520}, abstractNote={The advents of balloon angioplasty and of vascular bypass grafts have resulted in a paradigm shift in the management of cardiovascular diseases, but thrombus formation rising from the progression of intimal hyperplasia due to vessel damage and delayed arterial healing continue to be an intractable clinical failure of synthetic vascular bypass grafts. Nitric oxide (NO) releasing vascular bypass grafts have been developed as alternatives to conventional vascular grafts, but concerns over their short patency owing to the dissimilarity of mechanical properties between bypass grafts and innate arteries have recently been raised. Mismatch in mechanical properties at the endways inosculation of an artery and graft causes shear rate instabilities, which in turn stimulates intimal hyperplasia, thereby leading to graft failure. With the rapid development of manufacturing of innovative bypass grafts, no intervention has hitherto unequivocally proven to be clinically viscoelastic in preventing bypass graft failure. An ideal vascular graft closely mimics the structure and mechanical functions of native blood vessels and the configuration of each layer of the blood vessel. The overarching goal of this perspective is to highlight the importance and effects of mechanical properties of NO-releasing grafts in achieving optimal therapeutic outcomes for the management of cardiovascular diseases.}, journal={MECHANICS OF MATERIALS}, author={Tabish, Tanveer A. and Thorat, Nanasaheb D. and Narayan, Roger J.}, year={2023}, month={Jan} }
 @article{machekposhti_khanna_shukla_narayan_2023, title={Microneedle fabrication methods and applications}, ISSN={["2159-6867"]}, DOI={10.1557/s43579-023-00355-0}, abstractNote={Microneedles are microscale needle-shaped devices that have attracted attention from the biomedical engineering community for transdermal drug delivery, sensing, and vaccine delivery. These devices do not inflict significant discomfort during skin penetration. Microneedles have recently been used to detect physiologically relevant molecules in interstitial fluid for health monitoring. In this review, technical challenges associated with microneedle processing are considered. The mechanical requirements associated with microneedle penetration of the skin are described. The use of polymers, bioceramics, and natural materials in microneedle fabrication is described. Recent uses of microneedles in biosensing, drug delivery, and vaccine delivery are described. Graphical abstract}, journal={MRS COMMUNICATIONS}, author={Machekposhti, Sina Azizi and Khanna, Sumeer and Shukla, Shubhangi and Narayan, Roger}, year={2023}, month={Mar} }
 @article{shukla_machekposhti_joshi_joshi_narayan_2023, title={Microneedle-Integrated Device for Transdermal Sampling and Analyses of Targeted Biomarkers}, volume={4}, ISSN={["2688-4046"]}, url={http://dx.doi.org/10.1002/smsc.202200087}, DOI={10.1002/smsc.202200087}, abstractNote={Currently available point‐of‐care systems for body fluid collection exhibit poor integration with sensors. Herein, the design of a disposable device for interstitial fluid (ISF) extraction as well as glucose, lactate, and potassium ion (K+) monitoring is reported on. It is minimally invasive and appropriate for single use, minimizing the risk of infection to the user. This microscale device contains a 3D‐printed cap‐like structure with a four‐by‐four microneedle (MN) array, bioreceptor‐modified carbon fiber (CF)‐sensing surface, and negative pressure convection technology. These features are incorporated within a compact, self‐contained, and manually operated microscale device, which is capable of withdrawing ≈3.0 μL of ISF from the skin. MN arrays applied with an upward driving force may increase the ISF flow rate. Moreover, functionalized CF working electrodes (WE1, WE2, WE3) are shown to selectively detect lactate, glucose, and K+ with high sensitivities of 0.258, 0.549, and 0.657 μA μm−1 cm−2 and low detection limits of 0.01, 0.080, 0.05 μm, respectively. Ex vivo testing on porcine skin is used to detect the ISF levels of the biomarkers. The microscale device can be a replacement for current point‐of‐care diagnostic approaches.}, number={6}, journal={SMALL SCIENCE}, publisher={Wiley}, author={Shukla, Shubhangi and Machekposhti, Sina Azizi and Joshi, Naveen and Joshi, Pratik and Narayan, Roger J.}, year={2023}, month={Apr} }
 @article{khosla_narayan_narayan_sun_paranthaman_2023, title={Microstructure and defect engineering of graphite anodes by pulsed laser annealing for enhanced performance of lithium-ion batteries}, volume={205}, ISSN={["1873-3891"]}, url={https://doi.org/10.1016/j.carbon.2023.01.009}, DOI={10.1016/j.carbon.2023.01.009}, abstractNote={Nanosecond pulsed laser annealing significantly improves cyclability and current carrying capacity of lithium-ion batteries (LIBs). This improvement is achieved by engineering of microstructure and defect contents present in graphite in a controlled way by using pulsed laser annealing (PLA) to increase the number density of Li+ ion trapping sites. The PLA treatment causes the following changes: (1) creates surface steps and grooves between the grains to improve Li+ ion charging and intercalation rates; (2) removes inactive polyvinylidene difluoride (PVDF) binder from the top of graphite grains and between the grains which otherwise tends to block the Li+ migration; and (3) produces carbon vacancies in (0001) planes which can provide Li+ charging sites. From X-ray diffraction data, we find upshift in diffraction peak or reduction in planar spacing, from which vacancy concentration was estimated to be about 1.0%, which is higher than the thermodynamic equilibrium concentration of vacancies. The laser treatment creates single and multiple C vacancies which provide sites for Li+ ions, and it also produces steps and grooves for Li+ ions to enter the intercalating sites. It is envisaged that the formation of these sites enhances Li+ ion absorption during charge and discharge cycles. The current capacity increases from an average 360 mAh/g to 430 mAh/g, and C–V shows significant reduction in SEI layer formation after the laser treatment. If the vacancy concentration is too high and charge-discharge cycles are long, then trapping of electrons by Li+ may occur, which can lead to Li0 formation and Li plating causing reduction in current capacity.}, journal={CARBON}, author={Khosla, Nayna and Narayan, Jagdish and Narayan, Roger and Sun, Xiao-Guang and Paranthaman, Mariappan Parans}, year={2023}, month={Mar}, pages={214–225} }
 @article{khosla_narayan_narayan_sun_paranthaman_2023, title={Nanosecond Laser Annealing of NMC 811 Cathodes for Enhanced Performance}, volume={170}, ISSN={["1945-7111"]}, url={https://doi.org/10.1149/1945-7111/acc27d}, DOI={10.1149/1945-7111/acc27d}, abstractNote={Improved performance of lithium-ion batteries (LIBs) plays a critical role in the future of next- generation battery applications. Nickel-rich layered oxides such as LiNi0.8Mn0.1Co0.1O2 (NMC 811), are popular cathodes due to their high energy densities. However, they suffer from high surface reactivity, which results in the formation of Li2CO3 passive layer. Herein, we show the role of nanosecond pulsed laser annealing (PLA) in improving the current capacity and cycling stability of LIBs by reducing the carbonate layer, in addition to forming a protective LiF layer and manipulating the NMC 811 microstructures. We use high-power nanosecond laser pulses in a controlled way to create nanostructured surface topography which has a positive impact on the capacity retention and current capacity by providing an increased active surface area, which influences the diffusion kinetics of lithium-ions in the electrode materials during the battery cycling process. Advanced characterizations show that the PLA treatment results in the thinning of the passive Li2CO3 layer, which is formed on as-received NMC811 samples, along with the decomposition of excess polyvinylidene fluoride (PVDF) binder. The high-power laser interacts with the decomposed binder and surface Li+ to form LiF phase, which acts as a protective layer to prevent surface reactive sites from initiating parasitic reactions. As a result, the laser treated cathodes show relative increase of the current capacity of up to 50%, which is consistent with electrochemical measurements of LiB cells.}, number={3}, journal={JOURNAL OF THE ELECTROCHEMICAL SOCIETY}, author={Khosla, Nayna and Narayan, Jagdish and Narayan, Roger and Sun, Xiao-Guang and Paranthaman, M. Parans}, year={2023}, month={Mar} }
 @misc{machekposhti_kadian_vanderwal_stafslien_narayan_2023, title={Novel hollow biodegradable microneedle for amphotericin B delivery}, volume={4}, ISSN={["2688-2663"]}, DOI={10.1002/mco2.321}, abstractNote={Dear Editor, Several approaches have been previously described for incorporating drugs within polymer microneedles.1–5 Our previous study1 aimed to deliver amphotericin B by biodegradable solid microneedles. In this approach, amphotericin B was mixed with Gantrez R © AN 119 BF; the mixture of Gantrez R © AN 119 BF and amphotericin B was left at room temperature for approximately 2 weeks to be solidified in the shape of microneedle. Although the approach was successfully used with amphotericin B, it may not be suitable for some drugs.2 For example, the mechanical properties of some polymers may be lowered after being combined with certain drugs. Other studies involve coating microneedles with drugs; however, there may be a limit to the dosage that can be applied using the coating approach.4,5 To determine the volume of the amphotericin B loaded in each hollow microneedle, the amphotericin B-loaded microneedles were broken in tubes and dissolved in dimethyl sulfoxide:methanol; the amphotericin B concentration was determined by high-performance liquid chromatography. High-performance liquid chromatography indicated that there were 2.00 ± 0.08 mg of amphotericin B in each hollow microneedle. Laser confocal microscopy was used to assess the height, base diameter, and hollow features of the hollow microneedle. Figure 1A shows the length associated with the outer layer of a hollow microneedle, Figure 1B shows the length associated with the hollow part of a hollow microneedle, and Figure 1C shows the 3D image of a hollow microneedle. The height of the microneedle outer layer and microneedle base diameter are 858.03 and 424.82 μm, respectively. For the hollow part of the microneedle exhibits height, base diameter, and volume values of 653.75, 366.61 μm, and 2.3 × 107 μm3, respectively. Figure 1B shows the hollow part of a needle that can be loaded with amphotericin B powder or other drug powders. Since the base diameter measurement difference between Figures 1A and B is 58.21 μm, the thickness of the}, number={4}, journal={MEDCOMM}, author={Machekposhti, Sina Azizi and Kadian, Sachin and Vanderwal, Lyndsi and Stafslien, Shane and Narayan, Roger J.}, year={2023}, month={Aug} }
 @article{kadian_chaulagain_joshi_alam_cui_shankar_manik_narayan_2023, title={Probe sonication-assisted rapid synthesis of highly fluorescent sulfur quantum dots}, volume={34}, ISSN={["1361-6528"]}, url={http://dx.doi.org/10.1088/1361-6528/acd00a}, DOI={10.1088/1361-6528/acd00a}, abstractNote={AbstractA new type of heavy-metal free single-element nanomaterial, called sulfur quantum dots (SQDs), has gained significant attention due to its advantages over traditional semiconductor QDs for several biomedical and optoelectronic applications. A straightforward and rapid synthesis approach for preparing highly fluorescent SQDs is needed to utilize this nanomaterial for technological applications. Until now, only a few synthesis approaches have been reported; however, these approaches are associated with long reaction times and low quantum yields (QY). Herein, we propose a novel optimized strategy to synthesize SQDs using a mix of probe sonication and heating, which reduces the reaction time usually needed from 125 h to a mere 15 min. The investigation employs cavitation and vibration effects of high energy acoustic waves to break down the bulk sulfur into nano-sized particles in the presence of highly alkaline medium and oleic acid. In contrast to previous reports, the obtained SQDs exhibited excellent aqueous solubility, desirable photostability, and a relatively high photoluminescence QY up to 10.4% without the need of any post-treatment. Additionally, the as-synthesized SQDs show excitation-dependent emission and excellent stability in different pH (2–12) and temperature (20 °C–80 °C) environments. Hence, this strategy opens a new pathway for rapid synthesis of SQDs and may facilitate the use of these materials for biomedical and optoelectronic applications.}, number={30}, journal={NANOTECHNOLOGY}, publisher={IOP Publishing}, author={Kadian, Sachin and Chaulagain, Narendra and Joshi, Naveen Narasimhachar and Alam, Kazi M. and Cui, Kai and Shankar, Karthik and Manik, Gaurav and Narayan, Roger J.}, year={2023}, month={Jul} }
 @misc{kadian_shukla_narayan_2023, title={Probes for noninvasive biological visualization and biosensing of cancer cells}, volume={10}, ISSN={["1931-9401"]}, url={https://doi.org/10.1063/5.0166740}, DOI={10.1063/5.0166740}, abstractNote={The early detection of tumors and precancerous conditions is vital for cancer diagnosis. Advances in fluorescence microscopic techniques and materials synthesis processes have revolutionized biomarker detection and image-guided cancer surveillance. In particular, novel materials-based diagnostic tools and innovative therapies have facilitated a precise understanding of biological processes at the molecular level. This critical review presents an overview of bioimaging probes, including functionalized chromophoric systems, non-functionalized chromophoric systems, and nanoscale biosensors. Technical challenges and future directions related to these approaches are considered.}, number={4}, journal={APPLIED PHYSICS REVIEWS}, author={Kadian, Sachin and Shukla, Shubhangi and Narayan, Roger J.}, year={2023}, month={Dec} }
 @article{pandey_yadav_tiwari_sawant_sinharoy_banerjee_narayan_2023, title={Prussian blue nanoparticles-mediated sensing and removal of Cs-137}, volume={11}, ISSN={["2296-665X"]}, DOI={10.3389/fenvs.2023.1230983}, abstractNote={Prussian blue nanoparticles (PBNPs) with controlled nano-geometry were synthesized from a single precursor (potassium hexacyanoferrate) in the presence of three different reagents, namely, polyethylenimine (PEI), tetrahydrofuran (THF)/H2O2, and 2-(3,4-epoxycyclohexyl)-ethyl-trimethoxysilane (EETMS)/cyclohexanone, which enabled the controlled nucleation and stabilization of PBNPs of variable plasmonic activities for selective sensing and removal of cesium radionuclides. The results of this study show the sensing and removal of cesium ions based on the nano-geometry, magnetic behavior, and fluorescence quenching ability of PBNPs as a function of the cesium ion concentration for the first time. A similar process was used to synthetically incorporate PBNPs in mesoporous silica with potential use for the selective adsorption of 137Cs, followed by the detection of radioactivity. The distribution coefficient (Kd) for adsorption of the cesium nuclide 137Cs was calculated to be 3.2 × 104 mL/g−1, displaying both Langmuir and Freundlich adsorption isotherms. The plasmonic activity of PBNPs has enabled fluorometric sensing of cesium ions; regulating the spatial control between the functional PBNPs and fluorescence probe molecules is a promising approach for PBNP-enhanced fluorescence and fluorescence resonance energy transfer–based cesium ion sensing. Similarly, PBNPs display superparamagnetic behavior; these magnetic properties were observed to be linearly dependent on the cesium ion concentration.}, journal={FRONTIERS IN ENVIRONMENTAL SCIENCE}, author={Pandey, Prem C. and Yadav, Hari Prakash and Tiwari, Atul Kumar and Sawant, Shilpa N. and Sinharoy, Prithwish and Banerjee, Dayamoy and Narayan, Roger J.}, year={2023}, month={Aug} }
 @article{kadian_kumari_shukla_narayan_2023, title={Recent advancements in machine learning enabled portable and wearable biosensors}, volume={8}, ISSN={["2666-8319"]}, DOI={10.1016/j.talo.2023.100267}, abstractNote={Recent advances in noninvasive portable and wearable biosensors have attracted significant attention due to their capability to offer continual physiological information for continuous healthcare monitoring through the collection of biological signals. To make the collected biological data understandable and improve the efficacy of these biosensors, scientists have integrated machine learning (ML) with biosensors to analyze large sensing data through various ML algorithms. In this article, we have highlighted the recent developments in ML-enabled noninvasive biosensors. Initially, we introduced and discussed the basic features of ML algorithms used in data processing to build an intelligent biosensor system and the capability to make clinical decisions. Next, the principles of portable and wearable biosensors, the application of different ML models in diverse biosensors for healthcare applications, and their impact on the performance of biosensors are discussed. The last section highlights the challenges (such as data privacy, consistency, stability, accuracy, scalable production, and adaptive learning capacity), future prospects, and necessary steps required to address these issues, spotlighting their revolutionizing impact on the healthcare industry for the development of next-generation ML-enabled efficient biosensors.}, journal={TALANTA OPEN}, author={Kadian, Sachin and Kumari, Pratima and Shukla, Shubhangi and Narayan, Roger}, year={2023}, month={Dec} }
 @article{joshi_shivashankar_narayan_2023, title={Surfactant-free synthesis and magnetic property evaluation of air-stable cobalt oxide nanostructures}, volume={4}, ISSN={["2632-959X"]}, url={https://doi.org/10.1088/2632-959X/acf4ae}, DOI={10.1088/2632-959X/acf4ae}, abstractNote={Abstract
               We report the synthesis of metastable cobalt oxide (CoO) nanostructures via the low-temperature microwave-assisted solvothermal (MAS) process. An alcoholic solution of cobalt (II) acetylacetonate in a sealed vessel was irradiated with microwaves at a temperature <150 °C and a pressure below 100 psi. As-synthesized powder material was characterized in terms of its structure and morphology. X-ray diffractometry (XRD) indicates the formation of well-crystallized CoO nanoparticles without the need for post-synthesis annealing. The mean crystallite size of the nanoparticles was estimated to be 41 nm. The morphology of the as-prepared powder sample was evaluated by field-emission scanning electron microscopy (FESEM), which revealed the formation of densely packed nanospheres of diameter <100 nm. The CoO nanospheres were obtained without the need for any surfactants or capping agents; they were found to be quite resistant to oxidation in ambient air over several months. We attribute the stability of CoO nanospheres to their dense packing, the driving force being the minimization of surface energy and surface area. Fourier-transform infrared (FT-IR) spectroscopy and Raman spectroscopy confirm the formation of phase-pure CoO nanostructures. The deconvolution of the active modes in Raman spectra obtained at room temperature reveals the Oh symmetry in rock-salt CoO produced by the MAS route. We have analyzed its effect on the magnetic characteristics of the CoO nanostructures. Isothermal field-dependent magnetization (MH) and inverse magnetic susceptibility measurements show a phase transition from antiferromagnetic to ferromagnetic interactions in the CoO nanostructures at around 10 K. The results indicate that the phenomenon of magnetic phase transition as a function of temperature is unique to CoO nanoparticles. This finding reveals the magnetic behavior of CoO nanostructures and presents opportunities for its possible application as an anisotropy source for magnetic recording.}, number={3}, journal={NANO EXPRESS}, author={Joshi, Naveen and Shivashankar, S. A. and Narayan, Roger}, year={2023}, month={Sep} }
 @article{narayan_sahoo_joshi_narayan_2023, title={Synthesis and novel properties of Q-silicon (January 2023)}, volume={11}, ISSN={["2166-3831"]}, url={http://dx.doi.org/10.1080/21663831.2023.2224396}, DOI={10.1080/21663831.2023.2224396}, abstractNote={We report the discovery of Q-silicon with an atomic density of 60% higher than crystalline silicon while keeping the bonding characteristics the same as normal silicon. Distinct amorphous phases are created, when one, two, or three tetrahedra are randomly packed, and a crystalline phase of Q-silicon is formed when subunit cells are arranged along <110> directions with alternate holes. Nanosecond laser melting of amorphous silicon in an undercooled state and quenching have created Q-silicon with robust ferromagnetism compared to the diamagnetism of silicon. The blocking temperature of Q-silicon is estimated to be over 400 K, thus opening a new frontier for spin-based computing and atomic-level storage. GRAPHICAL ABSTRACT IMPACT STATEMENT The discovery of Q-silicon having robust RT ferromagnetism will open a new frontier in atomic-scale spin-based devices and functional integration with nanoelectronics. Other properties of interest include enhanced hardness and superconductivity.}, number={8}, journal={MATERIALS RESEARCH LETTERS}, publisher={Informa UK Limited}, author={Narayan, Jagdish and Sahoo, Siba Sundar and Joshi, Naveen and Narayan, Roger}, year={2023}, month={Aug}, pages={688–696} }
 @article{joshi_shukla_gupta_joshi_narayan_narayan_2023, title={Synthesis of laser-patterned MoS2 nanoneedles for advanced electrochemical sensing}, volume={6}, ISSN={["2159-6867"]}, url={http://dx.doi.org/10.1557/s43579-023-00381-y}, DOI={10.1557/s43579-023-00381-y}, abstractNote={We describe a novel excimer laser-based route for the fabrication of crystalline MoS2 nanoneedles. Laser annealing of MoS2 thin films at a low energy density of 0.08 Jcm−2 resulted in a closed-pack structure with low defects and excellent conductivity due to melting and rapid quenching. A further increase in laser annealing energy density resulted in the formation of MoS2 nano-needles. This structure of MoS2 was found to have a remarkable reduction ability for H2O2 at − 0.14 V over a wide linear range; a low detection limit (0.45 nM (S/N = 3)) and sensitivity of 2.38 μA/mM cm−2 were demonstrated.}, number={4}, journal={MRS COMMUNICATIONS}, publisher={Springer Science and Business Media LLC}, author={Joshi, Pratik and Shukla, Shubhangi and Gupta, Siddharth and Joshi, Naveen and Narayan, Jagdish and Narayan, Roger}, year={2023}, month={Jun} }
 @article{panicker_shamsheera_narayan_kotagiri_2023, title={Wearable Electrochemical Microneedle Sensors Based on the Graphene-Silver-Chitosan Nanocomposite for Real-Time Continuous Monitoring of the Depression Biomarker Serotonin}, volume={6}, ISSN={["2574-0970"]}, DOI={10.1021/acsanm.3c02976}, abstractNote={Wearable microneedle-based electrochemical sensor technologies are promptly growing due to their unique capabilities, such as minimally invasive, painless, real-time, continuous monitoring, etc. Strong disruptions or imbalances of neurotransmitter systems are associated with many chronic diseases and mental disorders, including Parkinson's, depression, anxiety, memory loss, significant changes in weight, and chronic physical or emotional stress. The captivating advantages of the wearable microneedle-based sensor enable continuous monitoring of various biomarkers and pharmaceutical drugs in interstitial fluid (ISF). In this present work, we have developed a sensor for continuous monitoring of the biologically important neurotransmitter Serotonin (5-hydroxytryptamine, 5-HT) through a microneedle patch. The new microneedle sensor array relies on Ag/rGO-modified carbon paste microneedle electrodes for square wave voltammetry and amperometry detection of the 5-HT target. Such real-time orthogonal sensing offers distinct, unique information and the desired analytical performance. The surfaces of the working electrodes have been characterized with electroanalytical and surface morphological techniques. The developed sensor was able to detect 5-HT target from phosphate-buffered saline buffer within linear ranges of 3–21 and 6–60 μM (both short and long ranges) with well-defined linearity. The continuous monitoring and biofouling studies of the microneedle sensor were demonstrated in artificial ISF containing bovine serum albumin by using chronoamperometry. The sensor exhibited linearity in the range of 13.5–95 μM. The long-term monitoring capability of the sensor was demonstrated in an artificial ISF medium. The specificity of the sensor was exhibited in the presence of potentially interfering substances. The excellent performance shown in the skin-mimicking model proved that the microneedle sensor platform holds considerable promise for real-time detection of the important neurotransmitter 5-HT in the ISF.}, number={22}, journal={ACS APPLIED NANO MATERIALS}, author={Panicker, Lakshmi R. and Shamsheera, Fathima and Narayan, Roger and Kotagiri, Yugender Goud}, year={2023}, month={Nov}, pages={20601–20611} }
 @misc{awad_goyanes_basit_zidan_xu_li_narayan_chen_2023, title={A Review of State-of-the-Art on Enabling Additive Manufacturing Processes for Precision Medicine}, volume={145}, ISSN={["1528-8935"]}, DOI={10.1115/1.4056199}, abstractNote={Abstract
               Precision medicine is an emerging healthcare delivery approach that considers variability between patients, such as genetic makeups, in contrast to the current one-size-fits-all approach that is designed to treat the average patient. The White House launched the Precision Medicine Initiative in 2015, starting an endeavor to reshape healthcare delivery. To translate the concept of precision medicine from the bench to practice, advanced manufacturing will play an integral part, including the fabrication of personalized drugs and drug delivery devices and drug screening platforms. These products are highly customized and require robust yet flexible manufacturing systems. The advanced manufacturing field has rapidly evolved in the past five years. In this state-of-the-art review, products manufactured for precision medicine will be introduced, followed by a brief review of processing materials and their characteristics. A review on different manufacturing processes applicable to those aforementioned products is provided. The current status of the development of regulatory submission and quality control considerations are also discussed. Finally, this paper presents a future outlook on manufacturing processes used for precision medicine.}, number={1}, journal={JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME}, author={Awad, Atheer and Goyanes, Alvaro and Basit, Abdul W. W. and Zidan, Ahmed S. S. and Xu, Changxue and Li, Wei and Narayan, Roger J. J. and Chen, Roland K. K.}, year={2023}, month={Jan} }
 @book{narayan_2022, place={Materials Park, OH}, title={Additive Manufacturing in Biomedical Applications}, ISBN={9781627083928}, url={http://dx.doi.org/10.31399/asm.hb.v23a.9781627083928}, DOI={10.31399/asm.hb.v23a.9781627083928}, abstractNote={Volume 23A provides a comprehensive review of established and emerging 3D printing and bioprinting approaches for biomedical applications, and expansive coverage of various feedstock materials for 3D printing. The Volume includes articles on 3D printing and bioprinting of surgical models, surgical implants, and other medical devices. The introductory section considers developments and trends in additively manufactured medical devices and material aspects of additively manufactured medical devices. The polymer section considers vat polymerization and powder-bed fusion of polymers. The ceramics section contains articles on binder jet additive manufacturing and selective laser sintering of ceramics for medical applications. The metals section includes articles on additive manufacturing of stainless steel, titanium alloy, and cobalt-chromium alloy biomedical devices. The bioprinting section considers laser-induced forward transfer, piezoelectric jetting, microvalve jetting, plotting, pneumatic extrusion, and electrospinning of biomaterials. Finally, the applications section includes articles on additive manufacturing of personalized surgical instruments, orthotics, dentures, crowns and bridges, implantable energy harvesting devices, and pharmaceuticals. For information on the print version of Volume 23A, ISBN: 978-1-62708-390-4, follow this link.}, publisher={ASM International}, year={2022}, month={Sep} }
 @article{yang_riley_rodenhausen_skoog_stafslien_vanderwal_narayan_2022, title={Antifungal behavior of silicon-incorporated diamond-like carbon by tuning surface hydrophobicity with plasma treatment}, ISSN={["1744-7402"]}, DOI={10.1111/ijac.14048}, abstractNote={Silicon-incorporated diamond-like carbon (Si-DLC), an amorphous material containing Si atoms with sp3- and sp2-hybridized carbon, is a promising biomaterial for versatile biomedical applications due to its excellent mechanical properties, chemical inertness, biocompatibility, and antimicrobial capability. However, the antifungal properties of plasma-treated Si-DLC have not been systematically evaluated. In this study, Si-DLC coatings were deposited by chemical vapor deposition and further treated with either oxygen or fluorine plasma to render the surface anchored with different functional groups and hydrophobicity. Surface roughness was probed with atomic force microscopy, whereas bonding character and surface composition were assessed using Raman and X-ray photoelectron spectroscopy. Wettability and surface charge were investigated via water contact angle and zeta potential measurements. Antifungal assessment was performed using a Candida albicans multi-well plate screening technique and crystal violet biomass quantification. The results demonstrate that oxygen plasma–treated Si-DLC exhibited hydrophilic properties, lower negative zeta potential, and significant antifungal behavior. This material can potentially be applied on surfaces for the prevention of reduced nosocomial infections.}, journal={INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY}, author={Yang, Kai-Hung and Riley, Parand and Rodenhausen, Keith B. and Skoog, Shelby A. and Stafslien, Shane J. and Vanderwal, Lyndsi and Narayan, Roger J.}, year={2022}, month={May} }
 @article{narayan_narayan_2022, title={Discovery of Double Helix and Impact on Nanoscale to Mesoscale Crystalline Structures}, volume={7}, ISSN={["2470-1343"]}, DOI={10.1021/acsomega.2c03501}, abstractNote={Screw dislocations play a significant role in the growth of crystalline structures by providing a continuous source of surface steps which represent available sites for crystal growth. Here, we show that pure screw dislocations can become helical from the absorption of defects (e.g., vacancies) and develop an attractive interaction with another helical dislocation to form a double helix of screw dislocations. These single and double helices of screw dislocations can result in the formation of interesting nanostructures with large Eshelby twists. We have previously proposed the formation of a double helix of screw dislocations to explain large Eshelby twists in crystalline nanostructures (Mater. Res. Lett.2021, 9, 453−457). We now show direct evidence for the formation of a double helix during thermal annealing of screw dislocations. The large Burgers vectors associated with these dislocations are used to explain the presence of large Eshelby twists in PbSe and PbS (NaCl cubic structure) and InP and GeS (wurtzite hexagonal structure) nanowires. These single- and double-helix screw dislocations can also combine to create even larger super Burgers vectors. These large effective Burgers also unravel the mechanism for the formation of nanopipes and micropipes with hollow cores and nanotubes with Eshelby twists in technologically important materials such as SiC, GaN, and ZnO that are utilized in a variety of advanced solid-state devices.}, number={29}, journal={ACS OMEGA}, author={Narayan, Jagdish and Narayan, Roger}, year={2022}, month={Jul}, pages={25853–25859} }
 @article{riley_yang_liu_skoog_narayan_narayan_2022, title={Effect of oxygen and fluorine plasma surface treatment of silicon-incorporated diamond-like carbon coatings on cellular responses of mouse fibroblasts}, volume={6}, ISSN={["1744-7402"]}, DOI={10.1111/ijac.14107}, abstractNote={AbstractThe surface chemistry of silicon‐incorporated diamond‐like carbon (Si‐DLC) was tailored utilizing oxygen and fluorine plasma treatments. Successful anchoring of oxygen and fluorine functional groups to the surface of Si‐DLC was verified using X‐ray photoelectron spectroscopy. The impact of surface modification of Si‐DLC on hydrophobicity was correlated with the viability of L929 mouse fibroblasts. The confocal microscopy and viability results indicated that oxygen‐treated Si‐DLC showed increased cell viability compared to untreated Si‐DLC and fluorine‐treated Si‐DLC samples 5 days after seeding. The increased cell viability was correlated with the conversion of the hydrophobic surface of Si‐DLC into a hydrophilic surface by oxygen plasma treatment.}, journal={INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY}, author={Riley, Parand R. and Yang, Kai-Hung and Liu, Yizhong and Skoog, Shelby A. and Narayan, Jagdish and Narayan, Roger J.}, year={2022}, month={Jun} }
 @article{nguyen_nelson_skoog_jaipan_petrochenko_kaiser_lo_moreno_narayan_goering_et al._2022, title={Effect of simulated body fluid formulation on orthopedic device apatite-forming ability assessment}, ISSN={["1552-4981"]}, DOI={10.1002/jbm.b.35207}, abstractNote={AbstractIntegration of native bone into orthopedic devices is a key factor in long‐term implant success. The material‐tissue interface is generally accepted to consist of a hydroxyapatite layer so bioactive materials that can spontaneously generate this hydroxyapatite layer after implantation may improve patient outcomes. Per the ISO 22317:2014 standard, “Implants for surgery – In vitro evaluation for apatite‐forming ability of implant materials,” bioactivity performance statements can be assessed by soaking the material in simulated body fluid (SBF) and evaluating the surface for the formation of a hydroxyapatite layer; however, variations in test methods may alter hydroxyapatite formation and result in false‐positive assessments. The goal of this study was to identify the effect of SBF formulation on bioactivity assessment. Bioglass® (45S5 and S53P4) and non‐bioactive Ti‐6Al‐4V were exposed to SBF formulations varying in calcium ion and phosphate concentrations as well as supporting ion concentrations. Scanning electron microscopy and X‐ray powder diffraction evaluation of the resulting hydroxyapatite layers revealed that SBF enriched with double or quadruple the calcium and phosphate ion concentrations increased hydroxyapatite crystal size and quantity compared to the standard formulation and can induce hydroxyapatite crystallization on surfaces traditionally considered non‐bioactive. Altering concentrations of other ions, for example, bicarbonate, changed hydroxyapatite induction time, quantity, and morphology. For studies evaluating the apatite‐forming ability of a material to support bioactivity performance statements, test method parameters must be adequately described and controlled. It is unclear if apatite formation after exposure to any of the SBF formulations is representative of an in vivo biological response. The ISO 23317 standard test method should be further developed to provide additional guidance on apatite characterization and interpretation of the results.}, journal={JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS}, author={Nguyen, Alexander K. K. and Nelson, Sarah B. B. and Skoog, Shelby A. A. and Jaipan, Panupong and Petrochenko, Peter E. E. and Kaiser, Aric and Lo, Linh and Moreno, Jose and Narayan, Roger J. J. and Goering, Peter L. L. and et al.}, year={2022}, month={Nov} }
 @article{joshi_shukla_gupta_riley_narayan_narayan_2022, title={Excimer Laser Patterned Holey Graphene Oxide Films for Nonenzymatic Electrochemical Sensing}, volume={14}, ISSN={["1944-8252"]}, url={https://doi.org/10.1021/acsami.2c09096}, DOI={10.1021/acsami.2c09096}, abstractNote={The existence of point defects, holes, and corrugations (macroscopic defects) induces high catalytic potential in graphene and its derivatives. We report a systematic approach for microscopic and macroscopic defect density optimization in excimer laser-induced reduced graphene oxide by varying the laser energy density and pulse number to achieve a record detection limit of 7.15 nM for peroxide sensing. A quantitative estimation of point defect densities was obtained using Raman spectroscopy and confirmed with electrochemical sensing measurements. Laser annealing (LA) at 0.6 J cm-2 led to the formation of highly reduced graphene oxide (GO) by liquid-phase regrowth of molten carbon with the presence of dangling bonds, making it catalytically active. Hall-effect measurements yielded a mobility of ∼200 cm2 V-1 s-1. An additional increase in the number of pulses at 0.6 J cm-2 resulted in deoxygenation through the solid-state route, leading to the formation of holey graphene structure. The average hole size showed a hierarchical increase, with the number of pulses characterized with multiple microscopy techniques, including scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. The exposure of edge sites due to high hole density after 10 pulses supported the formation of proximal diffusion layers, which led to facile mass transfer and improvement in the detection limit from 25.4 mM to 7.15 nM for peroxide sensing. However, LA at 1 J cm-2 with 1 pulse resulted in a high melt lifetime of molten carbon and the formation of GO characterized by a high resistivity of 3 × 10-2 Ω-cm, which was not ideal for sensing applications. The rapid thermal annealing technique using a batch furnace to generate holey graphene results in structure with uneven hole sizes. However, holey graphene formation using the LA technique is scalable with better control over hole size and density. This study will pave the path for cost-efficient and high-performance holey graphene sensors for advanced sensing applications.}, number={32}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Joshi, Pratik and Shukla, Shubhangi and Gupta, Siddharth and Riley, Parand R. and Narayan, Jagdish and Narayan, Roger}, year={2022}, month={Aug}, pages={37149–37160} }
 @article{riley_joshi_khosla_narayan_narayan_2022, title={Formation of Q-carbon with wafer scale integration}, volume={196}, ISSN={["1873-3891"]}, url={https://doi.org/10.1016/j.carbon.2022.06.003}, DOI={10.1016/j.carbon.2022.06.003}, abstractNote={We describe the formation of highly uniform Quenched-carbon (Q-carbon) layers by plasma-enhanced chemical vapor deposition (PECVD) followed by low-energy Ar+ ion bombardment to achieve wafer-scale integration of Q-carbon films. After PECVD, 9 nm and 20 nm thick silicon-doped diamond-like carbon (Si-DLC) films showed complete conversion into Q-carbon using 250eV Ar+ ions via negative biasing. However, this conversion was only partial for 30 nm thick films. Detailed EELS, XPS, Raman, and EDS studies were carried out to confirm the formation of Q-carbon by this method. We discuss the mechanism of Q-carbon formation as a result of low-energy ion bombardment during PECVD of thin films. These ions during negative biasing are energetic enough to create Frenkel defects, which support the conversion of the three-fold coordinated sp2 carbon units in as-deposited carbon into sp3 bonded five-atom tetrahedron units in Q-carbon. This process enhances the atomic number density and fraction of sp3 bonded carbon. These diamond tetrahedra are randomly packed and provide easy nucleation sites for diamond. If the underlying substrate can provide an epitaxial template for diamond growth via domain matching epitaxy, then wafer-scale growth of diamond epitaxial films can be achieved for wafer-scale integration and next-generation novel device manufacturing from diamond-related materials.}, journal={CARBON}, author={Riley, Parand R. and Joshi, Pratik and Khosla, Nayna and Narayan, Roger J. and Narayan, Jagdish}, year={2022}, month={Aug}, pages={972–978} }
 @article{joshi_riley_denning_shukla_khosla_narayan_narayan_2022, title={Laser-patterned carbon coatings on flexible and optically transparent plastic substrates for advanced biomedical sensing and implant applications}, volume={1}, ISSN={["2050-7534"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85125716163&partnerID=MN8TOARS}, DOI={10.1039/d1tc05176h}, abstractNote={Plasma and laser-based processing for tailoring DLC thin film properties for state-of-the-art wearable sensing applications.}, number={8}, journal={JOURNAL OF MATERIALS CHEMISTRY C}, publisher={Royal Society of Chemistry (RSC)}, author={Joshi, Pratik and Riley, Parand R. and Denning, Warren and Shukla, Shubhangi and Khosla, Nayna and Narayan, Jagdish and Narayan, Roger}, year={2022}, month={Jan} }
 @article{azizi machekposhti_nguyen_vanderwal_stafslien_narayan_2022, title={Micromolding of Amphotericin-B-Loaded Methoxyethylene-Maleic Anhydride Copolymer Microneedles}, volume={14}, ISSN={["1999-4923"]}, DOI={10.3390/pharmaceutics14081551}, abstractNote={Biocompatible and biodegradable materials have been used for fabricating polymeric microneedles to deliver therapeutic drug molecules through the skin. Microneedles have advantages over other drug delivery methods, such as low manufacturing cost, controlled drug release, and the reduction or absence of pain. The study examined the delivery of amphotericin B, an antifungal agent, using microneedles that were fabricated using a micromolding technique. The microneedle matrix was made from GantrezTM AN-119 BF, a benzene-free methyl vinyl ether/maleic anhydride copolymer. The GantrezTM AN-119 BF was mixed with water; after water evaporation, the polymer exhibited sufficient strength for microneedle fabrication. Molds cured at room temperature remained sharp and straight. SEM images showed straight and sharp needle tips; a confocal microscope was used to determine the height and tip diameter for the microneedles. Nanoindentation was used to obtain the hardness and Young’s modulus values of the polymer. Load–displacement testing was used to assess the failure force of the needles under compressive loading. These two mechanical tests confirmed the mechanical properties of the needles. In vitro studies validated the presence of amphotericin B in the needles and the antifungal properties of the needles. Amphotericin B GantrezTM microneedles fabricated in this study showed appropriate characteristics for clinical translation in terms of mechanical properties, sharpness, and antifungal properties.}, number={8}, journal={PHARMACEUTICS}, author={Azizi Machekposhti, Sina and Nguyen, Alexander K. and Vanderwal, Lyndsi and Stafslien, Shane and Narayan, Roger J.}, year={2022}, month={Aug} }
 @article{kumar_singh_chinappan_ghomi_singh_sandhu_ramakrishna_narayan_katakam_2022, title={On Mechanical, Physical, and Bioactivity Characteristics of Material Extrusion Printed Polyether Ether Ketone}, ISSN={["1544-1024"]}, DOI={10.1007/s11665-022-07519-4}, journal={JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE}, author={Kumar, Ranvijay and Singh, Gurminder and Chinappan, Amutha and Ghomi, Erfan Rezvani and Singh, Sunpreet and Sandhu, Kamalpreet and Ramakrishna, Seeram and Narayan, Roger and Katakam, Prakash}, year={2022}, month={Oct} }
 @article{narayan_joshi_smith_gao_weber_narayan_2022, title={Q-carbon as a new radiation-resistant material}, volume={186}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2021.10.006}, abstractNote={We have discovered that Q-carbon is extremely resistant to radiation damage under ion irradiations involving extreme atomic displacements and electronic excitations. Using 5 MeV Au + ions, the Q-carbon films on sapphire substrates were irradiated in the dose range 3.3–10 dpa (displacements-per-atom). After the ion irradiations, detailed studies on the atomic structure and bonding characteristics showed that atomic structure and bonding characteristics of amorphous Q-carbon remained essentially unchanged to 10 dpa of radiation damage, which is equivalent to over twenty years of neutron damage in a conventional reactor. There was an ion-beam mixed layer below the Q-carbon layer, whose thickness increased from 5 nm to 10 nm, as the dose increased from 3.3 to 10 dpa. This layer was found to be mostly amorphous with a mixture Al2O3 and Al4C3. This layer, formed as a result of enhanced forward scattering and ballistic ion beam mixing, exhibited composition consistent with detailed TRIM calculations. We also found that nanodiamonds (3 nm average size) embedded in Q-carbon grew to about 60 nm after 6.6 dpa and shrank to about 40 nm after 10 dpa. We discuss the mechanism for the growth and shrinkage of metastable phase of diamond under nonequilibrium ion irradiations.}, journal={CARBON}, author={Narayan, J. and Joshi, P. and Smith, J. and Gao, W. and Weber, W. J. and Narayan, R. J.}, year={2022}, month={Jan}, pages={253–261} }
 @misc{reddy_agarwal_ye_zhang_roy_chinnappan_narayan_ramakrishna_ghosh_2022, title={Recent Advancement in Biofluid-Based Glucose Sensors Using Invasive, Minimally Invasive, and Non-Invasive Technologies: A Review}, volume={12}, ISSN={["2079-4991"]}, DOI={10.3390/nano12071082}, abstractNote={Biosensors have potentially revolutionized the biomedical field. Their portability, cost-effectiveness, and ease of operation have made the market for these biosensors to grow rapidly. Diabetes mellitus is the condition of having high glucose content in the body, and it has become one of the very common conditions that is leading to deaths worldwide. Although it still has no cure or prevention, if monitored and treated with appropriate medication, the complications can be hindered and mitigated. Glucose content in the body can be detected using various biological fluids, namely blood, sweat, urine, interstitial fluids, tears, breath, and saliva. In the past decade, there has been an influx of potential biosensor technologies for continuous glucose level estimation. This literature review provides a comprehensive update on the recent advances in the field of biofluid-based sensors for glucose level detection in terms of methods, methodology and materials used.}, number={7}, journal={NANOMATERIALS}, author={Reddy, Vundrala Sumedha and Agarwal, Bhawana and Ye, Zhen and Zhang, Chuanqi and Roy, Kallol and Chinnappan, Amutha and Narayan, Roger J. and Ramakrishna, Seeram and Ghosh, Rituparna}, year={2022}, month={Apr} }
 @misc{joshi_riley_goud_mishra_narayan_2022, title={Recent advances of boron-doped diamond electrochemical sensors toward environmental applications}, volume={32}, ISSN={["2451-9103"]}, DOI={10.1016/j.coelec.2021.100920}, abstractNote={The electrocatalytic properties of boron-doped diamond (BDD) electrodes have been considered for a variety of sensing applications. The unusual electrochemical properties of BDD include a large potential window, a small background current, and better resistance to fouling than other carbon-based electrodes. The use of BDD for remediation and environmental sensing applications has recently attracted the interest of the sensor research community. This review focuses on recent developments that involve the use of BDD as an environmentally friendly sensing material for environmental analysis. The electrochemical properties of boron-doped diamond that has undergone surface modification (e.g., with metals or enzymes) will be considered. Recent achievements involving the use of BDD electrodes for detecting pesticides, mycotoxins, peroxides, and phenolic compounds are considered.}, journal={CURRENT OPINION IN ELECTROCHEMISTRY}, author={Joshi, Pratik and Riley, Parand and Goud, K. Yugender and Mishra, Rupesh K. and Narayan, Roger}, year={2022}, month={Apr} }
 @article{tiwari_gupta_pandey_tilak_narayan_pandey_2022, title={Size and Zeta Potential Clicked Germination Attenuation and Anti-Sporangiospores Activity of PEI-Functionalized Silver Nanoparticles against COVID-19 Associated Mucorales (Rhizopus arrhizus)}, volume={12}, ISSN={["2079-4991"]}, DOI={10.3390/nano12132235}, abstractNote={The SARS-CoV-2 infections in Indian people have been associated with a mucormycotic fungal infection caused by the filamentous fungi Rhizopus arrhizus. The sporangiospores of R. arrhizus are omnipresent in the environment and cause infection through inhalation or ingestion of contaminated air and foods. Therefore, the anti-sporangiospore activity of polyethyleneimine functionalized silver nanoparticles (PEI-f-Ag-NPs) with variable size and surface charge as a function of the molecular weight of PEI was explored. The results showed that both PEI-f-AgNP-1 and PEI-f-AgNP-2, potentially, attenuated the germination and reduced the viability of sporangiospores. Furthermore, the results showed that the minimum inhibitory concentration (MIC) values of both PEI-f-AgNP-1 and PEI-f-AgNP-2 (1.65 and 6.50 μg/mL, respectively) were dependent on the nanoparticle size and surface ζ potentials. Similarly, the sporangiospore germination inhibition at MIC values was recorded, showing 97.33% and 94% germination inhibition, respectively, by PEI-f-AgNP-1 and 2 within 24 h, respectively. The confocal laser scanning microscopy, SEM-EDS, and confocal Raman spectroscopy investigation of PEI-f-Ag-NPs treated sporangiospores confirmed size and surface charge-dependent killing dynamics in sporangiospores. To the best of our knowledge, this is the first investigation of the polyethyleneimine functionalized silver nanoparticle-mediated size and surface charge-dependent anti-sporangiospore activity against R. arrhizus, along with a possible antifungal mechanism.}, number={13}, journal={NANOMATERIALS}, author={Tiwari, Atul Kumar and Gupta, Munesh Kumar and Pandey, Govind and Tilak, Ragini and Narayan, Roger J. and Pandey, Prem C.}, year={2022}, month={Jul} }
 @article{shukla_joshi_riley_narayan_2022, title={Square wave voltammetric approach to leptin immunosensing and optimization of driving parameters with chemometrics}, volume={216}, ISSN={["1873-4235"]}, DOI={10.1016/j.bios.2022.114592}, abstractNote={Square wave voltammetry serves as an effective analytical means to evaluate antigen-antibody coupling at the solid-liquid interface. Herein, we describe 3-aminopropyltrimethoxysilane (APTMS) induced irreversible immobilization of anti-leptin to micellar gold nanoparticles (AuNPs). Antibodies (Abs) were orthogonally loaded on micellized AuNP assemblies via amino residual groups. The ratio of bound Ab molecules was determined by the Bradford assay. The AuNP/Ab layer modified electrodes with variable antibody surface coverage (∼400 ± 55–200 ± 30 Ab/NP) were analyzed in terms of change in backward, net current (Ip) components. The rate of antigen coupling was found to be consistent with the variation in antibody density as well as the binding affinity. The lowest detection limit was observed at the femtomolar level (0.25 fM/mL) over a wide range of antigen concentration (6.2 ng/mL to 0.12 fg/mL). The variables affecting the epitope-paratope interaction were further optimized using a chemometric approach and a response surface methodology (RSM).}, journal={BIOSENSORS & BIOELECTRONICS}, author={Shukla, Shubhangi and Joshi, Pratik and Riley, Parand and Narayan, Roger J.}, year={2022}, month={Nov} }
 @article{joshi_riley_mishra_machekposhti_narayan_2022, title={Transdermal Polymeric Microneedle Sensing Platform for Fentanyl Detection in Biofluid}, volume={12}, ISSN={["2079-6374"]}, DOI={10.3390/bios12040198}, abstractNote={Opioid drugs are extremely potent synthetic analytes, and their abuse is common around the world. Hence, a rapid and point-of-need device is necessary to assess the presence of this compound in body fluid so that a timely countermeasure can be provided to the exposed individuals. Herein, we present an attractive microneedle sensing platform for the detection of the opioid drug fentanyl in real serum samples using an electrochemical detection method. The device contained an array of pyramidal microneedle structures that were integrated with platinum (Pt) and silver (Ag) wires, each with a microcavity opening. The working sensor was modified by graphene ink and subsequently with 4 (3-Butyl-1-imidazolio)-1-butanesulfonate) ionic liquid. The microneedle sensor showed direct oxidation of fentanyl in liquid samples with a detection limit of 27.8 μM by employing a highly sensitive square-wave voltammetry technique. The resulting microneedle-based sensing platform displayed an interference-free fentanyl detection in diluted serum without conceding its sensitivity, stability, and response time. The obtained results revealed that the microneedle sensor holds considerable promise for point-of-need fentanyl detection and opens additional opportunities for detecting substances of abuse in emergencies.}, number={4}, journal={BIOSENSORS-BASEL}, author={Joshi, Pratik and Riley, Parand R. and Mishra, Rupesh and Machekposhti, Sina Azizi and Narayan, Roger}, year={2022}, month={Apr} }
 @article{shukla_huston_cox_satoskar_narayan_2022, title={Transdermal delivery via medical device technologies}, ISSN={["1744-7593"]}, DOI={10.1080/17425247.2022.2135503}, abstractNote={ABSTRACT Introduction Despite their effectiveness and indispensability, many drugs are poorly solvated in aqueous solutions. Over recent decades, the need for targeted drug delivery has led to the development of pharmaceutical formulations with enhanced lipid solubility to improve their delivery properties. Therefore, a dependable approach for administering lipid-soluble drugs needs to be developed. Areas covered The advent of 3D printing or additive manufacturing (AM) has revolutionized the development of medical devices, which can effectively enable the delivery of lipophilic drugs to the targeted tissues. This review focuses on the use of microneedles and iontophoresis for transdermal drug delivery. Microneedle arrays, inkjet printing, and fused deposition modeling have emerged as valuable approaches for delivering several classes of drugs. In addition, iontophoresis has been successfully employed for the effective delivery of macromolecular drugs. Expert opinion Microneedle arrays, inkjet printing, and fused deposition are potentially useful for many drug delivery applications; however, the clinical and commercial adoption rates of these technologies are relatively low. Additional efforts is needed to enable the pharmaceutical community to fully realize the benefits of these technologies.}, journal={EXPERT OPINION ON DRUG DELIVERY}, author={Shukla, Shubhangi and Huston, Ryan H. and Cox, Blake D. and Satoskar, Abhay R. and Narayan, Roger J.}, year={2022}, month={Oct} }
 @article{bandyopadhyay_bose_narayan_2022, title={Translation of 3D printed materials for medical applications}, ISSN={["1938-1425"]}, DOI={10.1557/s43577-021-00258-2}, abstractNote={During the past 30 years, 3D printing (3DP) technologies significantly influenced the manufacturing world, including innovation in biomedical devices. This special issue reviews recent advances in translating 3DP biomaterials and medical devices for metallic, ceramic, and polymeric devices, as well as bioprinting for organ and tissue engineering, along with regulatory issues in 3DP biomaterials. In our introductory article, besides introducing selected 3DP processes for biomaterials, current challenges and growth opportunities are also discussed. Finally, it highlights a few success stories for the 3D printed biomaterials for medical devices. We hope these articles will educate engineers, scientists, and clinicians about recent developments in translational 3DP technologies.}, journal={MRS BULLETIN}, author={Bandyopadhyay, Amit and Bose, Susmita and Narayan, Roger}, year={2022}, month={Feb} }
 @article{sachan_sachan_lu_erdmann_zhang_narayan_2021, title={3D Printing of Polytetrafluoroethylene Hollow Needles for Medical Applications}, ISSN={["1543-1851"]}, DOI={10.1007/s11837-021-04978-3}, journal={JOM}, author={Sachan, Roger and Sachan, Andrew and Lu, Junqi and Erdmann, Detlev and Zhang, Jennifer Y. and Narayan, Roger J.}, year={2021}, month={Oct} }
 @article{narayan_yoo_atala_2021, title={3D bioprinting: Physical and chemical processes}, volume={8}, ISSN={["1931-9401"]}, DOI={10.1063/5.0060283}, abstractNote={First Page}, number={3}, journal={APPLIED PHYSICS REVIEWS}, author={Narayan, Roger and Yoo, James and Atala, Anthony}, year={2021}, month={Sep} }
 @misc{joshi_riley_gupta_narayan_narayan_2021, title={Advances in laser-assisted conversion of polymeric and graphitic carbon into nanodiamond films}, volume={32}, ISSN={["1361-6528"]}, url={https://doi.org/10.1088/1361-6528/ac1097}, DOI={10.1088/1361-6528/ac1097}, abstractNote={Nanodiamond (ND) synthesis by nanosecond laser irradiation has sparked tremendous scientific and technological interest. This review describes efforts to obtain cost-effective ND synthesis from polymers and carbon nanotubes (CNT) by the melting route. For polymers, ultraviolet (UV) irradiation triggers intricate photothermal and photochemical processes that result in photochemical degradation, subsequently generating an amorphous carbon film; this process is followed by melting and undercooling of the carbon film at rates exceeding 109 K s−1. Multiple laser shots increase the absorption coefficient of PTFE, resulting in the growth of 〈110〉 oriented ND film. Multiple laser shots on CNTs result in pseudo topotactic diamond growth to form a diamond fiber. This technique is useful for fabricating 4–50 nm sized NDs. These NDs can further be employed as seed materials that are used in bulk epitaxial growth of microdiamonds using chemical vapor deposition, particularly for use with non-lattice matched substrates that formerly did not form continuous and adherent films. We also provide insights into biocompatible precursors for ND synthesis such as polybenzimidazole fiber. ND fabrication by UV irradiation of graphitic and polymeric carbon opens up a pathway for preparing selective coatings of polymer-diamond composites, doped nanodiamonds, and graphene composites for quantum computing and biomedical applications.}, number={43}, journal={NANOTECHNOLOGY}, publisher={IOP Publishing}, author={Joshi, Pratik and Riley, Parand and Gupta, Siddharth and Narayan, Roger J. and Narayan, Jagdish}, year={2021}, month={Oct} }
 @misc{lindberg_lim_soliman_nguyen_hooper_narayan_woodfield_2021, title={Biological function following radical photo-polymerization of biomedical polymers and surrounding tissues: Design considerations and cellular risk factors}, volume={8}, ISSN={["1931-9401"]}, DOI={10.1063/5.0015093}, abstractNote={Radical photo-cross-linking of polymers has been at the forefront in the development of biomedical applications to meet many of the biomaterial design criteria needed to address clinical and healthcare challenges, particularly in relation to regenerative and restorative medicine strategies, to treat damaged or diseased tissues and organs. Exciting new hybrid designs, elegantly expanding the range of properties and applications available to individual polymeric materials, are starting to offer detailed customization with complex and dynamic interactions similar to the events occurring within native tissue microenvironments in vivo. Yet the variety in success reported in the literature highlights the many unknown design criteria and parameters affecting functional restoration of damaged tissues and organs. The applied light curing units and radical initiating system, as well as underlying chemical reactions and resultant network structures, all require detailed consideration as means to modulate biological function while further being assessed as sources of toxicity. This is especially important when cells embedded in the polymeric material (or in surrounding tissues) are directly exposed to photo-irradiation. Ultimately, achieving successful clinical translation necessitates the chemical photo-polymerization platforms to be efficacious, safe, and customizable but also convenient for clinical use and cost-effective production. This review thus aims to summarize current and emerging toolkits to photo-polymerize biomedical polymers requiring the direct irradiation of cells and/or mammalian tissues and its associated impact on biological functionality. This specifically includes (1) in vitro photo-polymerization of cell-laden 3D-hydrogels for tissue engineering and regeneration medicine applications, (2) in vivo transdermal photo-polymerization of injectable hydrogels for cell/drug delivery, and (3) in vivo photo-polymerization of cell-free, injectable resin-based composites for load-bearing restorative surgery, all fast-growing and highly competitive fields of modern medicine. We herein summarize both design considerations and biological risk factors associated with selecting suitable light sources, photo-initiators, functional groups, chemical propagation, as well as how subsequent network properties can modulate biological function and ultimately clinical applicability. As more knowledge is continuously accumulated through materials science, matrix biology, and technology, this review provides recommendations for researchers to extend their chemical, biological, and structural characterizations to systematically enrich the paradigm of photo-polymerizable materials for biomedical applications to help ensure efficient and safe radical photo-processing.}, number={1}, journal={APPLIED PHYSICS REVIEWS}, author={Lindberg, Gabriella C. J. and Lim, Khoon S. and Soliman, Bram G. and Nguyen, Alexander and Hooper, Gary J. and Narayan, Roger J. and Woodfield, Tim B. F.}, year={2021}, month={Mar} }
 @misc{joshi_mishra_narayan_2021, title={Biosensing applications of carbon-based materials}, volume={18}, ISSN={["2468-4511"]}, DOI={10.1016/j.cobme.2021.100274}, abstractNote={Biosensors are used in a variety of applications ranging from prosthetic devices to food quality monitoring. The exploration of carbon nanomaterials for biosensing applications has involved extensive efforts by the research community due to the unique biochemical and physical properties, including optical, structural, mechanical, and thermal properties, of these materials. By virtue of these properties, materials such as graphene oxide, carbon nanotubes, graphite, nitrogen-vacancy center diamonds, ultrananocrystalline diamond, glassy carbon electrode, and graphene quantum dots have been widely studied. This article provides a description of recent efforts involving the use of carbon-based materials for biosensing and related biomedical applications.}, journal={CURRENT OPINION IN BIOMEDICAL ENGINEERING}, author={Joshi, Pratik and Mishra, Rupesh and Narayan, Roger J.}, year={2021}, month={Jun} }
 @article{yang_joshi_rodenhausen_sumant_skoog_narayan_2021, title={Correlation of zeta potential and contact angle of oxygen and fluorine terminated nitrogen incorporated ultrananocrystalline diamond (N UNCD) thin films}, volume={295}, ISSN={["1873-4979"]}, DOI={10.1016/j.matlet.2021.129823}, abstractNote={The surface chemistry of nitrogen incorporated ultrananocrystalline diamond (N-UNCD) films was altered by plasma treatment utilizing oxygen and fluorine plasma chemistries; the modified N-UNCD surfaces were characterized using contact angle and zeta potential measurements to give a more complete understanding of the interactions between the solid surface and the aqueous solution. The bonding character, surface composition, and morphology of the N-UNCD films before and after surface treatment were also monitored using X-ray photoelectron spectroscopy, atomic force microscopy, and Raman spectroscopy to ensure the grafting of functional groups; the contributing factor to the results was purely from the surface termination.}, journal={MATERIALS LETTERS}, author={Yang, Kai-Hung and Joshi, Pratik and Rodenhausen, Keith B. and Sumant, Anirudha V. and Skoog, Shelby A. and Narayan, Roger J.}, year={2021}, month={Jul} }
 @article{tabish_narayan_2021, title={Crossing the blood-brain barrier with graphene nanostructures}, volume={51}, ISSN={["1873-4103"]}, DOI={10.1016/j.mattod.2021.08.013}, abstractNote={Therapeutic approaches for the delivery of drugs to the central nervous system are hampered by the presence of the blood–brain barrier (BBB); overcoming this barrier is the clinical goal for the treatment of neurological disorders, including Alzheimer's disease and Parkinson's disease. The BBB is a cellular barrier of a highly impermeable nature that is predominantly formed by a tightly bound continuous layer of endothelial cells; it acts as a gatekeeper to restrict the free diffusion of bloodborne pathogens into the central nervous system. Targeted drug delivery systems have been explored over the past decade for crossing the BBB. Very recently, graphene nanostructures have shown great potential for crossing the BBB due to their exceptional features such as high electron mobility, ease of synthesis and functionalization, as well as control over size, shape, and the drug release profile. Graphene is evolving as a system not only to detect diseased lesions but also, in parallel, to treat neurological disorders while demonstrating minimal side effects. Given the rapid developments of innovative graphene-based delivery platforms, the present review sheds light on the status and prospects of graphene for crossing the BBB by improving, preserving, or rescuing brain energetics, with a specific focus on how graphene alters neuronal cell function.}, journal={MATERIALS TODAY}, author={Tabish, Tanveer A. and Narayan, Roger J.}, year={2021}, month={Dec}, pages={393–401} }
 @article{pandey_pandey_narayan_2021, title={Designing organotrialkoxysilane-functionalized microscale enzyme carrier: Spherical polymersomes with tunable catalytic potential}, ISSN={["2044-5326"]}, DOI={10.1557/s43578-021-00296-1}, abstractNote={This manuscript describes fabrication of a cross-linked and nanoengineered three-dimensional matrix of polymersomes for encapsulation of macromolecular cargo such as enzymes. Our approach involves the integration of glucose oxidase (GOx) enzyme into networks of a polysaccharide-silica matrix. Direct chemical cross-linking occurs between the residual groups of alginate polymer and the alkoxysilane moieties in a palladium nanoparticle dispersion; a transformation in the chemical configuration of the alginate hydrogel along with precise control over the pore size distribution facilitate immobilization of enzyme. The activity of the polymersomes was evaluated by enzymatic oxidation of the glucose substrate in phosphate buffer through loading different concentrations of GOx. In situ generated H_2O_2 was decomposed by the as-synthesized Prussian blue nanoparticles, which serve as an excellent peroxidase mimetic. The functional enzyme polymersome system was utilized for in vitro detection of blood glucose values. Graphic abstract}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Pandey, P. C. and Pandey, Ashsish Kumar and Narayan, Roger J.}, year={2021}, month={Jul} }
 @article{sachan_nguyen_lu_erdmann_zhang_narayan_2021, title={Digital light processing-based 3D printing of polytetrafluoroethylene solid microneedle arrays}, ISSN={["2159-6867"]}, DOI={10.1557/s43579-021-00121-0}, abstractNote={This study evaluated the structural and skin penetration properties of solid microneedle arrays made by digital light processing-based 3D printing of polytetrafluoroethylene. Confocal laser scanning microscopy and scanning electron microscopy revealed that the microneedles exhibited uniform heights. Raman spectroscopy, X-ray photoelectron spectroscopy, nanoindentation, and contact angle results indicated that the composition, carbon–fluorine bonding, reduced elastic modulus, and contact angle values of the 3D-printed polytetrafluoroethylene corresponded with those of bulk polytetrafluoroethylene, respectively. Methyl blue was used to evaluate the human skin penetration functionality of the microneedle array. Our results indicate that digital light processing is appropriate for manufacturing polytetrafluoroethylene medical devices.}, journal={MRS COMMUNICATIONS}, author={Sachan, Roger and Nguyen, Alexander K. and Lu, Junqi and Erdmann, Detlev and Zhang, Jennifer Y. and Narayan, Roger J.}, year={2021}, month={Nov} }
 @article{zhang_chung_barker_craig_narayan_huang_2021, title={Direct ink writing of polycaprolactone/polyethylene oxide based 3D constructs}, volume={31}, ISSN={["1745-5391"]}, DOI={10.1016/j.pnsc.2020.10.001}, abstractNote={There has been increasing interest over recent years in the application of three-dimensional (3D) printing technologies in the biomedical field. One such method is Direct Ink Writing (DIW); this approach has the potential advantage of allowing room-temperature deposition of materials, presented as an ink, to build complex architectures. DIW offers the ability to process biomaterials containing temperature-sensitive components. Due to the fabrication principles of DIW, there are specific rheological requirements that the ink must exhibit for the 3D construction. For this reason, hydrogel-based liquid feed stocks have been the focal point of ink development. As a consequence, studies based on inks comprising hydrophobic biomaterials, which are insoluble in water and hence unsuited to the hydrogel approach, have been limited. In this study, we investigate novel inks that utilize polycaprolactone (PCL), a hydrophobic polymer, as the primary constituent by dissolving the polymer in solvent systems based on dichloromethane (DCM) and acetone (ACE). Moreover, polyethylene oxide (PEO) was incorporated into the PCL systems in order to extend the range of hydrophilicity of the systems. The rheological properties of the inks were investigated as a function of polymer composition and solvent system. Woodpile constructs of PCL and PCL/PEO were fabricated using DIW method and were assessed by a series of material characterisation. The type of solvent system had a noticeable impact on the ink rheology, which ultimately affected the surface properties. The incorporation of PEO particularly enhanced the roughness and wettability of the constructs. Our results support the use of DIW as a new means to process hydrophobic polymers for biomedical applications.}, number={2}, journal={PROGRESS IN NATURAL SCIENCE-MATERIALS INTERNATIONAL}, author={Zhang, Bin and Chung, Se Hun and Barker, Susan and Craig, Duncan and Narayan, Roger J. and Huang, Jie}, year={2021}, month={Apr}, pages={166–177} }
 @article{zhang_nguyen_narayan_huang_2021, title={Direct ink writing of vancomycin-loaded polycaprolactone/ polyethylene oxide/ hydroxyapatite 3D scaffolds}, ISSN={["1551-2916"]}, DOI={10.1111/jace.18048}, abstractNote={AbstractNovel inks were formulated by dissolving polycaprolactone (PCL), a hydrophobic polymer, in organic solvent systems; polyethylene oxide (PEO) was incorporated to extend the range of hydrophilicity of the system. Hydroxyapatite (HAp) with a weight ratio of 55–85% was added to the polymer‐based solution to mimic the material composition of natural bone tissue. The direct ink writing (DIW) technique was applied to extrude the formulated inks to fabricate the predesigned tissue scaffold structures; the influence of HAp concentration was investigated. The results indicate that in comparison to other inks containing HAp (55%, 75%, and 85%w/w), the ink containing 65% w/w HAp had faster ink recovery behavior; the fabricated scaffold had a rougher surface as well as better mechanical properties and wettability. It is noted that the 65% w/w HAp concentration is similar to the inorganic composition of natural bone tissue. The elastic modulus values of PCL/PEO/HAp scaffolds were in the range of 4–12 MPa; the values were dependent on the HAp concentration. Furthermore, vancomycin as a model drug was successfully encapsulated in the PCL/PEO/HAp composite scaffold for drug release applications. This paper presents novel drug‐loaded PCL/PEO/HAp inks for 3D scaffold fabrication using the DIW printing technique for potential bone scaffold applications.}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Zhang, Bin and Nguyen, Alexander K. and Narayan, Roger J. and Huang, Jie}, year={2021}, month={Jul} }
 @article{yang_lindberg_soliman_lim_woodfield_narayan_2021, title={Effect of Photoinitiator on Precursory Stability and Curing Depth of Thiol-Ene Clickable Gelatin}, volume={13}, ISSN={["2073-4360"]}, DOI={10.3390/polym13111877}, abstractNote={Recent advances highlight the potential of photopolymerizable allylated gelatin (GelAGE) as a versatile hydrogel with highly tailorable properties. It is, however, unknown how different photoinitiating system affects the stability, gelation kinetics and curing depth of GelAGE. In this study, sol fraction, mass swelling ratio, mechanical properties, rheological properties, and curing depth were evaluated as a function of time with three photo-initiating systems: Irgacure 2959 (Ig2959; 320–500 nm), lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP; 320–500 nm), and ruthenium/sodium persulfate (Ru/SPS; 400–500 nm). Results demonstrated that GelAGE precursory solutions mixed with either Ig2959 or LAP remained stable over time while the Ru/SPS system enabled the onset of controllable redox polymerization without irradiation during pre-incubation. Photo-polymerization using the Ru/SPS system was significantly faster (<5 s) compared to both Ig2959 (70 s) and LAP (50 s). Plus, The Ru/SPS system was capable of polymerizing a thick construct (8.88 ± 0.94 mm), while Ig2959 (1.62 ± 0.49 mm) initiated hydrogels displayed poor penetration depth with LAP (7.38 ± 2.13 mm) in between. These results thus support the use of the visible light based Ru/SPS photo-initiator for constructs requiring rapid gelation and a good curing depth while Ig2959 or LAP can be applied for photo-polymerization of GelAGE materials requiring long-term incubation prior to application if UV is not a concern.}, number={11}, journal={POLYMERS}, author={Yang, Kai-Hung and Lindberg, Gabriella and Soliman, Bram and Lim, Khoon and Woodfield, Tim and Narayan, Roger J.}, year={2021}, month={Jun} }
 @article{mutlu_ulag_sengor_daglilar_narayan_gunduz_2021, title={Electrosprayed Collagen/Gentamicin nanoparticles coated microneedle patches for skin treatment}, volume={305}, ISSN={["1873-4979"]}, DOI={10.1016/j.matlet.2021.130844}, abstractNote={In this study, biocompatible microneedle patches were fabricated with three dimensional stereolithography (3D SLA) printer and coated with Gentamicin (GEN)-loaded Collagen (COL) nanoparticles fabricated with the electrospray method. The SEM results of the microneedles and COL/GEN nanoparticles coated microneedles showed that the nanosized microneedles were fabricated successfully, and these microneedles were coated with 1% COL/GEN solutions homogeneously. The release profiles of the GEN from the 1% COL/GEN nanoparticles coated microneedles reported that the drug was completely released within 540 min.}, journal={MATERIALS LETTERS}, author={Mutlu, Mehmet Eren and Ulag, Songul and Sengor, Mustafa and Daglilar, Sibel and Narayan, Roger and Gunduz, Oguzhan}, year={2021}, month={Dec} }
 @article{riley_joshi_azizi machekposhti_sachan_narayan_narayan_2021, title={Enhanced Vapor Transmission Barrier Properties via Silicon-Incorporated Diamond-Like Carbon Coating}, volume={13}, ISSN={["2073-4360"]}, DOI={10.3390/polym13203543}, abstractNote={In this study, we describe reducing the moisture vapor transmission through a commercial polymer bag material using a silicon-incorporated diamond-like carbon (Si-DLC) coating that was deposited using plasma-enhanced chemical vapor deposition. The structure of the Si-DLC coating was analyzed using scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, selective area electron diffraction, and electron energy loss spectroscopy. Moisture vapor transmission rate (MVTR) testing was used to understand the moisture transmission barrier properties of Si-DLC-coated polymer bag material; the MVTR values decreased from 10.10 g/m2 24 h for the as-received polymer bag material to 6.31 g/m2 24 h for the Si-DLC-coated polymer bag material. Water stability tests were conducted to understand the resistance of the Si-DLC coatings toward moisture; the results confirmed the stability of Si-DLC coatings in contact with water up to 100 °C for 4 h. A peel-off adhesion test using scotch tape indicated that the good adhesion of the Si-DLC film to the substrate was preserved in contact with water up to 100 °C for 4 h.}, number={20}, journal={POLYMERS}, author={Riley, Parand R. and Joshi, Pratik and Azizi Machekposhti, Sina and Sachan, Ritesh and Narayan, Jagdish and Narayan, Roger J.}, year={2021}, month={Oct} }
 @article{riley_joshi_narayan_narayan_2021, title={Enhanced nucleation and large-scale growth of CVD diamond via surface-modification of silicon-incorporated diamond-like carbon thin films}, volume={120}, ISSN={["1879-0062"]}, DOI={10.1016/j.diamond.2021.108630}, abstractNote={Herein we report a method to tailor the surface of silicon-incorporated diamond-like carbon (Si-DLC) thin films to enhance the diamond nucleation density and growth. In this technique, the surfaces of Si-DLC films were modified by fluorine and oxygen species utilizing a reactive-ion etching (RIE) method. The surface properties of Si-DLC, oxygen-terminated Si-DLC (O Si-DLC), and fluorine-terminated Si-DLC (F Si-DLC) films were investigated and compared. The analyses depicted that the sp2/sp3 ratio of carbon‑carbon bonds has diminished from 20.28% for Si-DLC film down to 8.96% and 4.41% for O Si-DLC and F Si-DLC films, respectively. Moreover, a significant amount of new sp3 hybridized bonds formed on the surface of the modified Si-DLC thin films, particularly in F Si-DLC film. The deposition of micro-diamond on the films was performed using hot filament chemical vapor deposition (HFCVD). SEM, XRD, and Raman results showed the enhancement in nucleation density and growth of micro-diamond on F Si-DLC and O Si-DLC films and the in-plane stress reduction up to 60%. Owing to the lower number of sp2 bonds and the greater number of new sp3 sites, the F Si-DLC thin film provided a superior platform for diamond nucleation than O Si-DLC film. The continuous diamond coverage on F Si-DLC film was up to ~2 mm2 versus ~0.4 mm2 for O Si-DLC film.}, journal={DIAMOND AND RELATED MATERIALS}, author={Riley, Parand R. and Joshi, Pratik and Narayan, Jagdish and Narayan, Roger J.}, year={2021}, month={Dec} }
 @article{narayan_bhaumik_gupta_joshi_riley_narayan_2021, title={Formation of self-organized nano- and micro-diamond rings}, volume={9}, ISSN={["2166-3831"]}, DOI={10.1080/21663831.2021.1907627}, abstractNote={We report formation of self-organized nanodiamond ring structures due to dynamical heterogeneity in super undercooled carbon, created by nanosecond laser melting of amorphous carbon layers. We envisage that diamond tetrahedra self-organize and lead to formation of string and ring structures on which nanodiamonds nucleate and grow. Denser ring structures are formed in Q-carbon due to higher undercooling and enhanced diamond nucleation. The average size is larger under heterogeneous nucleation compared to homogeneous nucleation due to lower critical size and free energy, allowing more time for growth. With nanosecond laser melting, growth velocities range 5–10 ms−1 and even higher for Q-carbon. GRAPHICAL ABSTRACT IMPACT STATEMENT Significant advancement in the creation of self-organized nanodiamond ring and string structures by laser processing at ambient pressure and temperature}, number={7}, journal={MATERIALS RESEARCH LETTERS}, author={Narayan, J. and Bhaumik, A. and Gupta, S. and Joshi, P. and Riley, P. and Narayan, R. J.}, year={2021}, month={Mar}, pages={300–307} }
 @misc{tabish_abbas_narayan_2021, title={Graphene nanocomposites for transdermal biosensing}, volume={13}, ISSN={["1939-0041"]}, DOI={10.1002/wnan.1699}, abstractNote={AbstractTransdermal biosensors for the real‐time and continuous detection and monitoring of target molecules represent an intriguing pathway for enhancing health outcomes in a cost‐effective and non‐invasive fashion. Many transdermal biosensor devices contain microneedles and other miniaturized components. There remains an unmet clinical need for microneedle transdermal biosensors to obtain a more accurate, rapid, and reliable insight into the real‐time monitoring of disease. The ability to monitor biomarkers at an intradermal molecular level in a non‐invasive manner remains the next technological gap to solve real‐world clinical problems. The emergence of the two‐dimensional material graphene with unique material properties and the ability to quantify analytes and physiological status can enable the detection of critical biomarkers indicative of human disease. The development of a user‐friendly, affordable, and non‐invasive transdermal biosensing device for continuous and personalized monitoring of target molecules could be beneficial for many patients. This focus article considers the use of graphene‐based transdermal biosensors for health monitoring, evaluation of these sensors for glucose and hydrogen peroxide detection via in vitro, in vivo, and ex vivo studies, recent technological innovations, and potential challenges.This article is categorized under:
Diagnostic Tools > Biosensing
}, number={4}, journal={WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY}, author={Tabish, Tanveer A. and Abbas, Aumber and Narayan, Roger J.}, year={2021}, month={Jul} }
 @article{sachan_schuerch_testa_hepp_koelmans_narayan_2021, title={Hollow copper microneedle made by local electrodeposition-based additive manufacturing}, ISSN={["2059-8521"]}, DOI={10.1557/s43580-021-00184-0}, abstractNote={Abstract Additive manufacturing offers the opportunity to manufacture microscale devices with custom designs such as microneedles, which have potential use in the transdermal delivery of vaccines or drugs. In this paper, a hollow microneedle was created out of copper using a local electrodeposition-based additive manufacturing processing. Scanning electron microscopy and confocal laser scanning microscopy revealed that the microneedle contained a sharp tip and a hollow bore. X-ray photoelectron spectroscopy showed the presence of copper, oxygen, copper, silicon, and sulfur and the absence of toxic impurities in a solid microneedle. These results suggest that local electrodeposition-based additive manufacturing of copper may be an appropriate approach for producing microneedles and many other types of microscale medical devices. Graphical abstract}, journal={MRS ADVANCES}, author={Sachan, Roger and Schuerch, Patrik and Testa, Paolo and Hepp, Edgar and Koelmans, Wabe W. and Narayan, Roger J.}, year={2021}, month={Dec} }
 @article{sachan_sachan_lu_sun_jin_erdmann_zhang_narayan_2021, title={Injection molding for manufacturing of solid poly(l-lactide-co-glycolide) microneedles}, volume={6}, ISSN={["2059-8521"]}, DOI={10.1557/s43580-021-00030-3}, abstractNote={Abstract A solid microneedle array can be used for “poke and flow” transdermal delivery of a drug, which involves the infusion or diffusion of a drug through pores in the skin that were created by the microneedle array. In this paper, solid microneedle arrays were created out of the polymer RESOMER LG 855 S—poly( l -lactide-co-glycolide) using injection molding. Scanning electron microscopy revealed that the microneedle in the injection-molded four-by-one microneedle array closely matched the dimensions that were used for injection molding. X-ray photoelectron spectroscopy revealed that the carbon bonding in the microneedle material matched that expected for poly( l -lactide-co-glycolide). The reduced elastic modulus of the microneedle material, 6.04 ± 0.17 GPa, was noted to be appropriate for skin penetration applications. The microneedle array was used for the delivery of the model drug methyl blue to surgically discarded human underarm skin. These results suggest that injection molding of RESOMER LG 855 S—poly( l -lactide-co-glycolide) may be an appropriate approach for large-scale manufacturing of solid microneedles. Graphic Abstract}, number={3}, journal={MRS ADVANCES}, author={Sachan, Andrew and Sachan, Roger J. and Lu, Junqi and Sun, Huiying and Jin, Yingai J. and Erdmann, Detlev and Zhang, Jennifer Y. and Narayan, Roger J.}, year={2021}, month={Apr}, pages={61–65} }
 @article{yang_yang_narayan_ma_2021, title={Laser-based bioprinting for multilayer cell patterning in tissue engineering and cancer research}, volume={65}, ISSN={["1744-1358"]}, DOI={10.1042/EBC20200093}, abstractNote={Abstract
               3D printing, or additive manufacturing, is a process for patterning functional materials based on the digital 3D model. A bioink that contains cells, growth factors, and biomaterials are utilized for assisting cells to develop into tissues and organs. As a promising technique in regenerative medicine, many kinds of bioprinting platforms have been utilized, including extrusion-based bioprinting, inkjet bioprinting, and laser-based bioprinting. Laser-based bioprinting, a kind of bioprinting technology using the laser as the energy source, has advantages over other methods. Compared with inkjet bioprinting and extrusion-based bioprinting, laser-based bioprinting is nozzle-free, which makes it a valid tool that can adapt to the viscosity of the bioink; the cell viability is also improved because of elimination of nozzle, which could cause cell damage when the bioinks flow through a nozzle. Accurate tuning of the laser source and bioink may provide a higher resolution for reconstruction of tissue that may be transplanted used as an in vitro disease model. Here, we introduce the mechanism of this technology and the essential factors in the process of laser-based bioprinting. Then, the most potential applications are listed, including tissue engineering and cancer models. Finally, we present the challenges and opportunities faced by laser-based bioprinting.}, number={3}, journal={3D BIOPRINTING}, author={Yang, Haowei and Yang, Kai-Hung and Narayan, Roger J. and Ma, Shaohua}, year={2021}, pages={409–416} }
 @article{joshi_gupta_riley_narayan_narayan_2021, title={Liquid phase regrowth of (110) nanodiamond film by UV laser annealing of PTFE to generate dense CVD microdiamond film}, volume={117}, ISSN={["1879-0062"]}, DOI={10.1016/j.diamond.2021.108481}, abstractNote={Herein we report the conversion of polytetrafluoroethylene (PTFE) into 〈110〉 nanodiamonds via a melting route using pulsed laser annealing (PLA). The converted nanodiamond (ND) film is used as a seed layer to grow dense microdiamond coating synthesized by chemical vapor deposition. We utilize an ArF excimer laser with a photon energy of 6.4 eV to decompose PTFE (bandgap: 6.0 eV). Initial laser pulses result in photochemical decomposition of PTFE, and PTFE is converted to an amorphous carbon film. This amorphous carbon film, when subjected to additional laser pulses melts, and when this melt is quenched from an undercooled state at rates exceeding 109 K/s, it undergoes first-order phase transformation into the ND film. Notably, the obtained NDs are phase pure, exhibiting full width at half maxima (FWHM) of 1.23 cm−1 and demonstrating 〈110〉 out of plane orientation characterized by Raman spectroscopy and transmission electron microscopy, respectively. The average ND size is ~28.5 nm (range: 5-30 nm) determined by scanning electron microscopy and X-ray diffraction. The COMSOL simulations substantiate the use of nanosecond laser pulses with an energy density in the range of 0.6–0.8 J/cm2 to fully convert ~ 50% crystalline PTFE into ND film. The CVD microdiamonds grew densely on the ND seed layer as compared to reduced graphene oxide confirmed by SEM and Raman analysis. This innovative method of ND fabrication by UV irradiation of PTFE opens up opportunities for generating selective coatings of advanced polymer-diamond composites and doped nanodiamonds for quantum computing and biomedical applications.}, journal={DIAMOND AND RELATED MATERIALS}, author={Joshi, Pratik and Gupta, Siddharth and Riley, Parand R. and Narayan, Roger J. and Narayan, Jagdish}, year={2021}, month={Aug} }
 @misc{tabish_narayan_2021, title={Mitochondria-targeted graphene for advanced cancer therapeutics}, volume={129}, ISSN={["1878-7568"]}, DOI={10.1016/j.actbio.2021.04.054}, abstractNote={There have been numerous efforts to develop targeted therapies for treating cancer. The non-specificity of 'classical' cytotoxic chemotherapy drugs and drug resistance remain major challenges in cancer dormancy. Mitochondria-targeted therapy is an alternative strategy for the treatment of numerous cancer types and is heavily dependent on the ability of the anticancer drugs to reach the tumor mitochondria in a safe and selective manner. Over the past two decades, research efforts have provided mechanistic insights into the roles of mitochondria in cancer progression and therapies that specifically target cancer mitochondria. Given that several nanotechnology-driven strategies aimed at therapeutically targeting mitochondrial dysfunction are still in their infancy, this review considers the cross-disciplinary nature of this area and focuses on the design and development of mitochondria-targeted graphene (mitoGRAPH), its immense potential, and future use for selective targeting of cancer mitochondria. This review also provides novel insights into the strategies for preparing mitoGRAPH to destroy the cell powerhouse in a targeted fashion. Targeting mitochondria with graphene may represent an important therapeutic approach that transforms therapeutic interventions. Mitochondria-targeted therapy represents a major advance for treating several medical conditions. At this time, no nanoparticles (NPs) or nanocarriers are clinically available, which are capable of spatial targeting and controlled delivery of drugs to mitochondria. NPs-based approaches have revolutionized the field of targeted therapy and have demonstrated efficacy for delivering drugs selectively to mitochondria. These NPs show limited results in pre-clinical animal models due to their adverse side effects and inadequate therapeutic outcomes. Over the past decade, graphene has emerged as a potential anticancer agent and has shown great potential in targeting tumor mitochondria in a safe and targeted fashion. This review considers recent advances in the use of mitochondria-targeted graphene (mitoGRAPH) in chemotherapy, photodynamic therapy, photothermal therapy, and combination therapies.}, journal={ACTA BIOMATERIALIA}, author={Tabish, Tanveer A. and Narayan, Roger J.}, year={2021}, month={Jul}, pages={43–56} }
 @article{papich_narayan_2021, title={Naloxone and nalmefene absorption delivered by hollow microneedles compared to intramuscular injection}, volume={11}, ISSN={["2190-3948"]}, url={https://doi.org/10.1007/s13346-021-01096-0}, DOI={10.1007/s13346-021-01096-0}, abstractNote={Naloxone and nalmefene were administered to seven research beagle dogs (mean weight approximately 12 kg) at doses of 0.04 mg/kg and 0.014 mg/kg for naloxone and nalmefene, respectively. Each dose was administered intramuscularly (IM) with a standard IM injection and with a hollow microneedle device array using needles of 1 mm in length. The IM injection was delivered in the epaxial muscles, and the microneedle injection was delivered in the skin over the shoulder of each dog. Each dog received the same injections in a crossover design. Following the injection, blood samples were collected for plasma analysis of naloxone and nalmefene by high-pressure liquid chromatography with mass spectrometry detection (LCMS). The plasma sample concentrations were plotted for observed patterns of absorption and analyzed with non-compartmental pharmacokinetic methods (NCA). The results showed that the injection of naloxone from the microneedle device produced a higher peak concentration (CMAX) by 2.15 × compared the IM injection of the same dose, and time to peak concentration (TMAX) was similar. For the nalmefene injection, the peak was not as high (lower CMAX) by 0.94 × for the microneedle injection compared to the IM injection of the same dose. The microneedle produced an exposure, measured by area under the curve (AUC), that was 0.85 × and 0.58 × as high for naloxone and nalmefene, respectively, than the injection by the IM route. We also observed that although the dose for naloxone was approximately 3 × higher for naloxone compared to nalmefene, the mean peak concentration achieved from the naloxone injection was more than 12 × higher than that from the nalmefene injection. These studies were designed to test the feasibility of using the hollow microneedle array as an effective method of naloxone and nalmefene delivery for emergency treatment of opioid-induced respiratory depression (OIRD). The results of these studies will form the basis of future studies, using the dog as a model, for development of hollow microneedle microarray devices to deliver opioid antagonists for treatment of OIRD in people.}, journal={DRUG DELIVERY AND TRANSLATIONAL RESEARCH}, publisher={Springer Science and Business Media LLC}, author={Papich, Mark G. and Narayan, Roger J.}, year={2021}, month={Nov} }
 @misc{pandey_shukla_pandey_narayan_2021, title={Nanostructured diamond for biomedical applications}, volume={32}, ISSN={["1361-6528"]}, DOI={10.1088/1361-6528/abd2e7}, abstractNote={Abstract
               Nanostructured forms of diamond have been recently considered for use in a variety of medical devices due to their unusual biocompatibility, corrosion resistance, hardness, wear resistance, and electrical properties. This review considers several routes for the synthesis of nanostructured diamond, including chemical vapor deposition, hot filament chemical vapor deposition, microwave plasma-enhanced chemical vapor deposition, radio frequency plasma-enhanced chemical vapor deposition, and detonation synthesis. The properties of nanostructured diamond relevant to medical applications are described, including biocompatibility, surface modification, and cell attachment properties. The use of nanostructured diamond for bone cell interactions, stem cell interactions, imaging applications, gene therapy applications, and drug delivery applications is described. The results from recent studies indicate that medical devices containing nanostructured diamond can provide improved functionality over existing materials for the diagnosis and treatment of various medical conditions.}, number={13}, journal={NANOTECHNOLOGY}, author={Pandey, Prem C. and Shukla, Shubhangi and Pandey, Govind and Narayan, Roger J.}, year={2021}, month={Mar} }
 @article{narayan_basu_goel_jones_jung_2021, title={Next generation bioceramics}, ISSN={["1551-2916"]}, DOI={10.1111/jace.18246}, abstractNote={Journal of the American Ceramic SocietyVolume 105, Issue 3 p. 1615-1616 EDITORIAL Next generation bioceramics Roger Narayan, Corresponding Author Roger Narayan rjnaraya@ncsu.edu orcid.org/0000-0002-4876-9869 Department of Biomedical Engineering, North Carolina State University, Raleigh, NC, USA Correspondence Roger Narayan, Department of Biomedical Engineering, North Carolina State University, Raleigh, NC 27695-7115, USA Email: rjnaraya@ncsu.eduSearch for more papers by this authorBikramjit Basu, Bikramjit Basu Materials Research Center, Indian Institute of Science, Bangalore, IndiaSearch for more papers by this authorAshutosh Goel, Ashutosh Goel orcid.org/0000-0003-0139-9503 Department of Materials Science and Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USASearch for more papers by this authorJulian Jones, Julian Jones orcid.org/0000-0002-2647-8024 Department of Materials, Imperial College London, South Kensington, London, United KingdomSearch for more papers by this authorSteve Jung, Steve Jung Mo-Sci Corporation, Rolla, MO, USASearch for more papers by this author Roger Narayan, Corresponding Author Roger Narayan rjnaraya@ncsu.edu orcid.org/0000-0002-4876-9869 Department of Biomedical Engineering, North Carolina State University, Raleigh, NC, USA Correspondence Roger Narayan, Department of Biomedical Engineering, North Carolina State University, Raleigh, NC 27695-7115, USA Email: rjnaraya@ncsu.eduSearch for more papers by this authorBikramjit Basu, Bikramjit Basu Materials Research Center, Indian Institute of Science, Bangalore, IndiaSearch for more papers by this authorAshutosh Goel, Ashutosh Goel orcid.org/0000-0003-0139-9503 Department of Materials Science and Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USASearch for more papers by this authorJulian Jones, Julian Jones orcid.org/0000-0002-2647-8024 Department of Materials, Imperial College London, South Kensington, London, United KingdomSearch for more papers by this authorSteve Jung, Steve Jung Mo-Sci Corporation, Rolla, MO, USASearch for more papers by this author First published: 20 November 2021 https://doi.org/10.1111/jace.18246Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume105, Issue3Special Issue: Next Generation BioceramicsMarch 2022Pages 1615-1616 RelatedInformation}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Narayan, Roger and Basu, Bikramjit and Goel, Ashutosh and Jones, Julian and Jung, Steve}, year={2021}, month={Dec} }
 @article{riley_joshi_penchev_narayan_narayan_2021, title={One-Step Formation of Reduced Graphene Oxide from Insulating Polymers Induced by Laser Writing Method}, volume={11}, ISSN={["2073-4352"]}, DOI={10.3390/cryst11111308}, abstractNote={Finding a low-cost and effective method at low temperatures for producing reduced graphene oxide (rGO) has been the focus of many efforts in the research community for almost two decades. Overall, rGO is a promising candidate for use in supercapacitors, batteries, biosensors, photovoltaic devices, corrosion inhibitors, and optical devices. Herein, we report the formation of rGO from two electrically insulating polymers, polytetrafluoroethylene (PTFE) and meta-polybenzimidazole fiber (m-PBI), using an excimer pulsed laser annealing (PLA) method. The results from X-ray diffraction, scanning electron microscopy, electron backscattered diffraction, Raman spectroscopy, and Fourier-transform infrared spectroscopy confirm the successful generation of rGO with the formation of a multilayered structure. We investigated the mechanisms for the transformation of PTFE and PBI into rGO. The PTFE transition occurs by both a photochemical mechanism and a photothermal mechanism. The transition of PBI is dominated by a photo-oxidation mechanism and stepwise thermal degradation. After degradation and degassing procedures, both the polymers leave behind free molten carbon with some oxygen and hydrogen content. The free molten carbon undergoes an undercooling process with a regrowth velocity (<4 m·s−1) that is necessary for the formation of rGO structures. This approach has the potential for use in creating future selective polymer-written electronics.}, number={11}, journal={CRYSTALS}, author={Riley, Parand R. and Joshi, Pratik and Penchev, Hristo and Narayan, Jagdish and Narayan, Roger J.}, year={2021}, month={Nov} }
 @misc{sharma_mishra_goud_mohamed_kummari_tiwari_li_narayan_stanciu_marty_2021, title={Optical Biosensors for Diagnostics of Infectious Viral Disease: A Recent Update}, volume={11}, ISSN={["2075-4418"]}, DOI={10.3390/diagnostics11112083}, abstractNote={The design and development of biosensors, analytical devices used to detect various analytes in different matrices, has emerged. Biosensors indicate a biorecognition element with a physicochemical analyzer or detector, i.e., a transducer. In the present scenario, various types of biosensors have been deployed in healthcare and clinical research, for instance, biosensors for blood glucose monitoring. Pathogenic microbes are contributing mediators of numerous infectious diseases that are becoming extremely serious worldwide. The recent outbreak of COVID-19 is one of the most recent examples of such communal and deadly diseases. In efforts to work towards the efficacious treatment of pathogenic viral contagions, a fast and precise detection method is of the utmost importance in biomedical and healthcare sectors for early diagnostics and timely countermeasures. Among various available sensor systems, optical biosensors offer easy-to-use, fast, portable, handy, multiplexed, direct, real-time, and inexpensive diagnosis with the added advantages of specificity and sensitivity. Many progressive concepts and extremely multidisciplinary approaches, including microelectronics, microelectromechanical systems (MEMSs), nanotechnologies, molecular biology, and biotechnology with chemistry, are used to operate optical biosensors. A portable and handheld optical biosensing device would provide fast and reliable results for the identification and quantitation of pathogenic virus particles in each sample. In the modern day, the integration of intelligent nanomaterials in the developed devices provides much more sensitive and highly advanced sensors that may produce the results in no time and eventually help clinicians and doctors enormously. This review accentuates the existing challenges engaged in converting laboratory research to real-world device applications and optical diagnostics methods for virus infections. The review’s background and progress are expected to be insightful to the researchers in the sensor field and facilitate the design and fabrication of optical sensors for life-threatening viruses with broader applicability to any desired pathogens.}, number={11}, journal={DIAGNOSTICS}, author={Sharma, Atul and Mishra, Rupesh Kumar and Goud, K. Yugender and Mohamed, Mona A. and Kummari, Shekher and Tiwari, Swapnil and Li, Zhanhong and Narayan, Roger and Stanciu, Lia A. and Marty, Jean Louis}, year={2021}, month={Nov} }
 @article{azizi machekposhti_zhang_sachan_vanderwal_stafslien_narayan_2021, title={Patterned surfaces with the controllable drug doses using inkjet printing}, volume={36}, ISSN={["2044-5326"]}, DOI={10.1557/s43578-021-00135-3}, abstractNote={A mixture of microflora, including  Staphylococcus aureus ,  Pseudomonas aeruginosa , and  Candida albicans , is found in burns and traumatic wounds. In this study, piezoelectric inkjet printing was used to apply an antifungal agent, amphotericin B, and an antibacterial agent, azithromycin, to the surfaces of gauze, silicon, and aluminum. The in vitro disk diffusion assay was performed on the unmodified, dimethyl sulfoxide vehicle-modified, azithromycin-modified, and amphotericin B-modified surfaces. Unlike the unmodified and dimethyl sulfoxide vehicle-modified surfaces, the amphotericin B-modified surfaces showed antifungal activity against  C. albicans ; the azithromycin-modified surfaces showed antibacterial activity against  Staphylococcus aureus  and  P. aeruginosa . The dimethyl sulfoxide vehicle-modified surface did not show activity against  S. aureus ,  P. aeruginosa , or  C. albicans . The results indicate that piezoelectric inkjet printing may be useful for loading gauze with both antibacterial and antifungal pharmacologic agents with poor solubility in aqueous solutions for the treatment of mixed wounds. Graphical abstract Disk diffusion assay from the inkjet printing-modified surfaces as determined using Staphylococcus aureus .}, number={19}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Azizi Machekposhti, Sina and Zhang, Bin and Sachan, Roger and Vanderwal, Lyndsi and Stafslien, Shane J. and Narayan, Roger J.}, year={2021}, month={Oct}, pages={3865–3876} }
 @misc{riley_narayan_2021, title={Recent advances in carbon nanomaterials for biomedical applications: A review}, volume={17}, ISSN={["2468-4511"]}, DOI={10.1016/j.cobme.2021.100262}, abstractNote={With the emergence of new pathogens like coronavirus disease 2019 and the prevalence of cancer as one of the leading causes of mortality globally, the effort to develop appropriate materials to address these challenges is a critical research area. Researchers around the world are investigating new types of materials and biological systems to fight against various diseases that affect humans and animals. Carbon nanostructures with their properties of straightforward functionalization, capability for drug loading, biocompatibility, and antiviral properties have become a major focus of biomedical researchers. However, reducing toxicity, enhancing biocompatibility, improving dispersibility, and enhancing water solubility have been challenging for carbon-based biomedical systems. The goal of this article is to provide a review on the latest progress involving the use of carbon nanostructures, namely fullerenes, graphene, and carbon nanotubes, for drug delivery, cancer therapy, and antiviral applications.}, journal={CURRENT OPINION IN BIOMEDICAL ENGINEERING}, author={Riley, Parand R. and Narayan, Roger J.}, year={2021}, month={Mar} }
 @article{narayan_bhaumik_gupta_joshi_riley_narayan_2021, title={Role of Q-carbon in nucleation and formation of continuous diamond film}, volume={176}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2021.02.049}, abstractNote={Formation of continuous and adherent diamond films on practical substrates presents a formidable challenge due to lack of diamond nucleation sites needed for diamond growth. This problem has been solved through the formation of interfacial Q-carbon layers by nanosecond laser melting of carbon layers in a highly undercooled state and subsequent quenching. The Q-carbon layer provides ready nucleation sites for epitaxial films on planar matching substrates such as sapphire, and polycrystalline films on amorphous substrates such as glass. Each laser pulse converts about a one-cm-square area, which can be repeated with a 100–200 Hz laser to produce potentially 100–200 cm2s-1 of diamond films. This is essentially a low-temperature processing, where substrate stays close to ambient temperature, because the total heat input is quite small. The Q-carbon layer is also responsible for improved adhesion of diamond films on sapphire and glass substrates. It is also argued that the formation of Q-carbon layer is also responsible for efficient diamond nucleation during negatively biased MPCVD diamond depositions.}, journal={CARBON}, author={Narayan, J. and Bhaumik, A. and Gupta, S. and Joshi, P. and Riley, P. and Narayan, R. J.}, year={2021}, month={May}, pages={558–568} }
 @article{joshi_haque_gupta_narayan_narayan_2021, title={Synthesis of multifunctional microdiamonds on stainless steel substrates by chemical vapor deposition}, volume={171}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2020.09.064}, abstractNote={We report on the synthesis of multifunctional microdiamonds by chemical vapor deposition (CVD) on 304 and 316 austenitic stainless steel (SS) substrates. The increase in wettability achieved by surface scratching and the structure of ultra-dense Q-carbon achieved high nucleation density and minimized strains in diamond films. Notably, these diamond films exhibit a high amount of twinning, leading to the formation of five-fold microdiamonds. The diamonds on scratched SS substrate and Q-carbon interlayer exhibit a full width at half maximum of 8.25 cm−1 and 11.5 cm−1, compared to 26 cm−1 on bare SS substrate. The diamond films grown on bare SS substrate exhibited cracking due to high tensile stress of 2.3 GPa, ascribed to thermal mismatch between SS and diamond. The electron backscattered diffraction investigations reveal iron inclusions in diamonds synthesized on bare SS substrates, which may create ferromagnetism in these diamonds. This route, compared to the ion beam implantation method using ferromagnetic ions, yields better samples. At 800 °C, 1012 Fe atoms/cm2s are transferred from the SS substrate into the diamonds. The dominant growth orientation for these CVD diamonds was determined to be <110> out of plane. These multifunctional microdiamonds are useful for biomedical, electronic, and tribological applications.}, journal={CARBON}, author={Joshi, Pratik and Haque, Ariful and Gupta, Siddharth and Narayan, Roger J. and Narayan, Jagdish}, year={2021}, month={Jan}, pages={739–749} }
 @article{baldacchini_saksena_sklare_vinson_huang_chrisey_narayan_2021, title={Translation of laser-based three-dimensional printing technologies}, ISSN={["1938-1425"]}, DOI={10.1557/s43577-021-00042-2}, abstractNote={Laser-based three-dimensional (3D) printing methods, including laser direct-write cell printing and two-photon polymerization, have seen significant advances because of their unique photonic characteristics. Several mechanisms have been developed to increase the overall throughput of two-photon polymerization. Recent efforts to develop complex medically relevant structures using laser direct-write cell printing have also been demonstrated; for example, an ex vivo experimental platform for time-lapse imaging of cancer cell dynamics during angiogenesis within a microvascular network, which combines laser direct-write cell printing into the rat mesentery culture model; a model that simulates a 3D in vivo culture. Laser 3D printing methods hold significant promise for 3D printing of tissue engineering scaffolds, microstructured medical devices, and other medically relevant structures.}, journal={MRS BULLETIN}, author={Baldacchini, Tommaso and Saksena, Jayant and Sklare, Samuel C. and Vinson, Benjamin T. and Huang, Yong and Chrisey, Douglas B. and Narayan, Roger J.}, year={2021}, month={Feb} }
 @article{haque_narayan_2021, title={Tunable n-Type Conductivity and Transport Properties of Cubic Boron Nitride via Carbon Doping}, volume={3}, ISSN={["2637-6113"]}, DOI={10.1021/acsaelm.0c01130}, abstractNote={The recent discovery of direct conversion of hexagonal boron nitride (h-BN) into quenched BN (Q-BN) and single-crystal cubic BN (c-BN) by pulsed laser annealing (PLA) have been implemented to fabri...}, number={3}, journal={ACS APPLIED ELECTRONIC MATERIALS}, author={Haque, Ariful and Narayan, Jagdish}, year={2021}, month={Mar}, pages={1359–1367} }
 @article{movahed_nguyen_goering_skoog_narayan_2020, title={Argon and oxygen plasma treatment increases hydrophilicity and reduces adhesion of silicon-incorporated diamond-like coatings}, volume={15}, ISSN={["1559-4106"]}, DOI={10.1116/6.0000356}, abstractNote={In this study, the structure, adhesion, and cell viability characteristics of silicon-incorporated diamond-like carbon (Si-DLC) coatings on fused silica substrates were investigated. The effects of argon and oxygen postprocessing plasma treatments on the Si-DLC coatings were also studied. The contact angle results showed that the Si-DLC coatings were more hydrophilic than the uncoated surfaces, and postprocessing plasma treatment increased the hydrophilicity of the Si-DLC coatings. Atomic force microscopy and profilometry confirmed that postprocessing plasma treatment increased the thickness and roughness of the Si-DLC coatings. The results of microscratch testing indicated that the plasma treatments reduced the adhesion of the coatings. The x-ray photoelectron spectroscopy (XPS) showed the presence of carbon, oxygen, and silicon in the Si-DLC coatings before and after the plasma treatments. These results show that the postprocessing plasma treatment significantly reduced the atomic percentage of the carbon in the Si-DLC coatings. XPS also confirmed the presence of carbon in the form of sp3(C—C), sp2(C=C), C—O, and C=O bonds in the Si-DLC coatings; it showed that postprocessing treatments significantly increased the percentage of oxygen in the Si-DLC coatings. Fourier transform infrared spectroscopy (FTIR) analysis showed features associated with C—OH stretching, C—H bending, as well as Si—CH2 and C—H bending in the Si-DLC coating. The XPS and FTIR results confirmed that the plasma treatment caused dissociation of the sp2 and sp3 bonds and formation of C—OH bonds. The contact angle data indicated that postprocessing treatment increased the hydrophilicity of the Si-DLC coating. Similar to the uncoated substrates, L929 cells showed no change in cell viability when cultured on Si-DLC coatings. These results of the study indicate the suitability of Si-DLC coatings as inert coatings for medical and biotechnology applications.}, number={4}, journal={BIOINTERPHASES}, author={Movahed, Saeid and Nguyen, Alexander K. and Goering, Peter L. and Skoog, Shelby A. and Narayan, Roger J.}, year={2020}, month={Jul} }
 @article{haque_narayan_2020, title={Conversion of h-BN into c-BN for tuning optoelectronic properties}, volume={1}, ISSN={["2633-5409"]}, DOI={10.1039/d0ma00008f}, abstractNote={Phase pure c-BN and mixed phased h-BN and c-BN films on c-sapphire were fabricated by pulsed laser annealing for tuning optical properties.}, number={4}, journal={MATERIALS ADVANCES}, author={Haque, Ariful and Narayan, Jagdish}, year={2020}, month={Jul}, pages={830–836} }
 @article{pandey_tiwari_gupta_pandey_narayan_2020, title={Effect of the Organic Functionality on the Synthesis and Antimicrobial Activity of Silver Nanoparticles}, volume={10}, ISSN={["1793-9852"]}, DOI={10.1142/S1793984420500026}, abstractNote={ In this paper, the effects of the organic reducing agent and 3-aminopropyltrimethoxysilane on the synthesis and properties of mono-, bi-, and trimetallic noble metal nanoparticles were considered; the antimicrobial activity of these nanomaterials was also evaluated. It was shown that 3-aminoptopyltrimethoxysilane-treated noble metal cations undergo rapid conversion into nanoparticles in the presence of three organic reducing agents, namely, 3-glycidoxypropyltrimethoxysilane (3-GPTMS), cyclohexanone and formaldehyde; the nanoparticles were formed on the order of one minute under microwave incubation. Bimetallic nanoparticles were formed by simultaneous or sequential reduction of metal cations; the formation of trimetallic nanoparticles containing gold, silver and palladium was demonstrated using a similar approach. The nanoparticles were characterized using UV-Visible light spectrophotometry, transmission electron microscopy and zeta potential measurements. All three nanoparticles exhibited a size [Formula: see text]10[Formula: see text]nm size. The nanoparticles showed antimicrobial activity against Acinetobacter baumannii. Scanning electron microscopy imaging showed an alteration in the size and shape of nanoparticle-treated bacterium, with bleb formation and cell wall disruption observed within 1[Formula: see text]h of incubation at the MBC values of the nanoparticles. Fluorescence spectrophotometric imaging of silver nanoparticle-Acinetobacter baumannii interactions suggested selective binding of silver nanoparticles to surface proteins. Our results showed the preparation of the novel silver nanoparticles with potent Anti-Acinetobacter baumannii activity, which can serve as an alternative to conventional antimicrobial agents. }, number={3}, journal={NANO LIFE}, author={Pandey, P. C. and Tiwari, Atul Kumar and Gupta, Munesh Kumar and Pandey, Govind and Narayan, Roger J.}, year={2020}, month={Sep} }
 @article{gupta_joshi_narayan_2020, title={Electron mobility modulation in graphene oxide by controlling carbon melt lifetime}, volume={170}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2020.07.073}, abstractNote={The lack of bandgap is a fundamental issue in graphene devices, which can be solved by fabricating reduced graphene oxide (rGO). However, its device integration is impeded by the elevated reduction temperature (>2000 K) requirements. Recently, we demonstrated a new approach for laser writing heavily-reduced GO by employing the nonequilibrium approach of nanosecond laser annealing (Gupta and Narayan, 2019) [1]. Here, we report on the electron mobility modulation in the liquid phase grown graphene oxide. The process involves melting and subsequent quenching of molten carbon, which triggers the first-order phase transformation of amorphous carbon (a-C) into rGO. Laser annealing at energy density above the 0.3 J/cm2 melting threshold results in liquid-phase rGO growth on Si/SiO2. The rGO films exhibit 26 cm2/V-s room-temperature electron mobility and −4.7 × 1021/cc charge carrier concentration on annealing near melt threshold. The heavily-reduced GO films are formed on -O- creeping in the loosely-packed low undercooled carbon melt during ultrafast quenching. We establish that -O- injection is an implicit function of melt lifetime, and a rise in melt lifetime triggers GO film regrowth with increased mobility >210 cm2/V-s and 2.2 × 1019/cc carrier concentration on annealing at 0.6 J/cm2. Laser annealing resolves the fundamental issues of impurities and topological defects in rGO fabrication by equilibrium-based methods, facilitating increased electron mobility in laser patterned graphene-based materials.}, journal={CARBON}, author={Gupta, Siddharth and Joshi, Pratik and Narayan, Jagdish}, year={2020}, month={Dec}, pages={327–337} }
 @misc{zhang_huang_narayan_2020, title={Gradient scaffolds for osteochondral tissue engineering and regeneration}, volume={8}, ISSN={["2050-7518"]}, DOI={10.1039/d0tb00688b}, abstractNote={The tissue engineering approach for repairing osteochondral (OC) defects involves the fabrication of a biological tissue scaffold that mimics the physiological properties of natural OC tissue (e.g., the gradient transition between the cartilage surface and the subchondral bone).}, number={36}, journal={JOURNAL OF MATERIALS CHEMISTRY B}, author={Zhang, Bin and Huang, Jie and Narayan, Roger J.}, year={2020}, month={Sep}, pages={8149–8170} }
 @article{cristescu_negut_visan_nguyen_sachan_goering_chrisey_narayan_2020, title={Matrix-Assisted Pulsed laser Evaporation-deposited Rapamycin Thin Films Maintain Antiproliferative Activity}, volume={6}, ISSN={["2424-8002"]}, DOI={10.18063/ijb.v6i1.188}, abstractNote={Matrix-assisted pulsed laser evaporation (MAPLE) has many benefits over conventional methods (e.g., dip-coating, spin coating, and Langmuir&ndash;Blodgett dip-coating) for manufacturing coatings containing pharmacologic agents on medical devices. In particular, the thickness of the coating that is applied to the surface of the medical device can be tightly controlled. In this study, MAPLE was used to deposit rapamycin-polyvinylpyrrolidone (rapamycin-PVP) thin films onto silicon and borosilicate optical glass substrates. Alamar Blue and PicoGreen studies were used to measure the metabolic health and DNA content of L929 mouse fibroblasts as measures of viability and proliferation, respectively. The cells on the MAPLE-deposited rapamycin-PVP surfaces exhibited 70.6% viability and 53.7% proliferation compared to a borosilicate glass control. These data indicate that the antiproliferative properties of rapamycin were maintained after MAPLE deposition.}, number={1}, journal={INTERNATIONAL JOURNAL OF BIOPRINTING}, author={Cristescu, Rodica and Negut, Irina and Visan, Anita Ioana and Nguyen, Alexander K. and Sachan, Andrew and Goering, Peter L. and Chrisey, Douglas B. and Narayan, Roger J.}, year={2020}, pages={105–111} }
 @article{pandey_pandey_narayan_2021, title={Microneedle-based transdermal electrochemical biosensors based on Prussian blue-gold nanohybrid modified screen-printed electrodes}, volume={109}, ISSN={["1552-4981"]}, DOI={10.1002/jbm.b.34678}, abstractNote={AbstractWe report on the fabrication of a microneedle‐based electrochemical biosensor for use in transdermal biosensing, which includes a screen‐printed electrode containing a Prussian blue‐gold nanohybrid as the working electrode. The Prussian blue gold nanohybrid is made from polyethylenime (PEI)‐ mediated simultaneous synthesis of Prussian blue (PBNP) and gold nanoparticles (AuNP), which forms a PBNP‐AuNP nanohybrid with a remarkable change in the Prussian blue character. PEI‐protected polycrystalline PBNPs can be synthesized in acidic media from the single precursor potassium ferricyanide [K3Fe(CN)6] at 60°C. Since PEI also enables the controlled formation of gold nanoparticles (AuNPs) in the presence of formaldehyde, nanohybrids containing PBNPs and AuNPs may be prepared. Two different methods of PEI mediated synthesis of AuNP in the presence of PBNP were considered. In Method 1, AuNP and PBNP were made independently and mixed together in an appropriate ratio. In Method 2, PBNPs were made first, followed by PEI‐ and formaldehyde‐mediated reduction of gold cations in the presence of PBNP. PBNP‐AuNPs display a remarkable change in Prussian blue behavior such that the absorption maxima of PBNP‐AuNPs made through Method 1 tend to increase at 670 nm as a function of gold concentration as compared with the control; the reverse was observed when PBNP‐AuNPs were made through Method 2. As made PBNPs and PBNP‐AuNPs made through Method 1 display excellent catalytic activity toward both reduction and oxidation of hydrogen peroxide based on peroxidase mimetic activity. In addition, the as‐synthesized PBNPs displayed superparamagnetic behavior that can be manipulated in the presence of AuNPs. The results from peroxidase mimetic activity, chemiluminescence, cyclic voltammetry, and amperometry showed suitable analytical performance of the as‐made PBNP‐AuNP nanohybrid for biomedical applications.}, number={1}, journal={JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS}, author={Pandey, Prem C. and Pandey, Govind and Narayan, Roger J.}, year={2021}, month={Jan}, pages={33–49} }
 @misc{pandey_pandey_narayan_2020, title={Minimally Invasive Platforms in Biosensing}, volume={8}, ISSN={["2296-4185"]}, DOI={10.3389/fbioe.2020.00894}, abstractNote={The interaction of sensing components with body fluids is a basic requirement for clinical diagnostics; a variety of novel platforms have recently been developed for invasive and non-invasive sensing. In this manuscript, recent advancements related to minimally invasive platform for biosensing are reviewed. Many approaches have been utilized for generating minimally invasive platforms that require a small volume of body fluid; for example, the use of small-scale needles known as microneedles for minimally invasive detection has been demonstrated. The use of capillary action in microneedle-assisted biosensing may facilitate the detection of analytes in body fluids. This review considers recent innovations in the structure and performance of minimally invasive sensos.}, journal={FRONTIERS IN BIOENGINEERING AND BIOTECHNOLOGY}, author={Pandey, Prem C. and Pandey, Govind and Narayan, Roger J.}, year={2020}, month={Aug} }
 @article{tiwari_gupta_pandey_narayan_pandey_2020, title={Molecular weight of polyethylenimine-dependent transfusion and selective antimicrobial activity of functional silver nanoparticles}, volume={35}, ISSN={["2044-5326"]}, DOI={10.1557/jmr.2020.183}, abstractNote={Abstract}, number={18}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Tiwari, Atul Kumar and Gupta, Munesh Kumar and Pandey, Govind and Narayan, Roger J. and Pandey, Prem C.}, year={2020}, month={Sep}, pages={2405–2415} }
 @misc{yang_boehm_skoog_narayan_2020, title={Nanostructured Medical Adhesives}, volume={16}, ISSN={["1550-7041"]}, DOI={10.1166/jbn.2020.2897}, abstractNote={Suturing has been the gold standard approach to close wounds for many decades. However, suturing causes tissue damage, which is accompanied by foreign body reaction, entry of pathogens, complications, infection, or death. In addition, the procedure is usually time-consuming, requiring
 manual dexterity and free moving space. Other adhesive approaches have been proposed and demonstrated with great potential, including laser-assisted tissue closure with either photothermal or photochemical reactions, application of nanoparticles, glues, constructs based on extracellular matrix
 (ECM), microbarbs, bio-inspired structures, and tape. The quality of closure has been evaluated by histological methods, indexing, morphology, tensile testing, patency rate, leakage pressure, and burst pressure. All the novel tissue joining methods aim to provide an adhesive with appropriate
 strength, non-cytotoxicity, and minimal damage. The capability for rapid attachment and release may further reduce surgical procedure time. More research is needed to prove the feasibility of new tissue joining techniques based on the type of tissue, surface chemistry, and working environment.}, number={3}, journal={JOURNAL OF BIOMEDICAL NANOTECHNOLOGY}, author={Yang, Kai-Hung and Boehm, Ryan D. and Skoog, Shelby A. and Narayan, Roger J.}, year={2020}, month={Mar}, pages={263–282} }
 @article{zhang_huang_narayan_2020, title={Nanostructured biomaterials for regenerative medicine: Clinical perspectives}, ISBN={["978-0-08-102594-9"]}, ISSN={["2049-9485"]}, DOI={10.1016/B978-0-08-102594-9.00003-6}, abstractNote={This chapter provides an overview of innovative platform technologies based on nanostructured biomaterials as a function of their material properties as well as their role in tissue engineering and regenerative medicine. Nanostructured ceramics, metals, polymers, and their composites are discussed regarding their applications as bioengineered tissue substitutes in vitro and in vivo and clinical trials. The study also summarizes important parameters related to the use of nanostructured biomaterials (e.g., chemical, mechanical, and structural property) for tissue regeneration and addresses possible directions for future investigation.}, journal={NANOSTRUCTURED BIOMATERIALS FOR REGENERATIVE MEDICINE}, author={Zhang, Bin and Huang, Jie and Narayan, Roger}, year={2020}, pages={47–80} }
 @article{pandey_shukla_pandey_narayan_2020, title={Organotrialkoxysilane-mediated controlled synthesis of noble metal nanoparticles and their impact on selective fluorescence enhancement and quenching}, volume={38}, ISSN={["2166-2754"]}, DOI={10.1116/6.0000334}, abstractNote={Ordered noble metal nanoparticles functionalized with organotrialkoxysilanes [e.g., 2-(3, 4-epoxycyclohexyl) ethyltrimethoxysilane (EETMS), 3-aminopropyltrimethoxysilane (APTMS), and 3-glycidoxypropyltrimethoxysilane (GPTMS)] were used as substrates to investigate the variation in fluorescence intensity of some well-known fluorophores (e.g., fluorescein, rhodamine, and l-tryptophan) based on distance effects and surface plasmonic activity. Anisotropic palladium nanoparticles (PdNPs), gold nanospheres (AuNPs), and silver nanospheres (AgNPs) were synthesized as a function of concentration of EETMS, APTMS, or GPTMS; the organotrialkoxysilane concentration directed the growth rate of particles along certain crystallographic facets. The reactive organic functionalities of alkoxysilanes facilitated the physisorption of probe molecules in proximity to the nanoparticles. The maximum enhancement in fluorescence intensity was observed in the case of APTMS-induced stabilization at hydrodynamic radii (RH) of ∼350 nm as a result of specific interactions with fluorescein molecules; quenching was mostly observed close for interactions between the GPTMS-functionalized nanoparticles and fluorophores. The smaller size of l-tryptophan and the absence of effective plasmonic coupling with PdNPs and AuNPs surfaces in the 290–370 nm emission range resulted in quenching; an appreciable far-field linking with AgNPs was noted around an emission wavelength of 360–375 nm, which resulted in several fold enhancement in intensity. Alkoxysilanes were shown to regulate the spatial control between the functionalized nanoparticles. As such nanoparticles, alkoxysilane-derived nanomaterials, may serve as promising platforms for metal enhanced fluorescence and fluorescence resonance energy transfer.}, number={5}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Pandey, Prem C. and Shukla, Shubhangi and Pandey, Govind and Narayan, Roger J.}, year={2020}, month={Sep} }
 @article{pandey_shukla_pandey_narayan_2020, title={Organotrialkoxysilane-mediated synthesis of functional noble metal nanoparticles and their bimetallic for electrochemical recognition of L-tryptophan}, volume={5}, ISSN={["2059-8521"]}, DOI={10.1557/adv.2020.305}, abstractNote={Effective and pH-sensitive electrochemical monitoring of L-tryptophan using noble metal nanocatalysts was evaluated in this study. This work examined the electrocatalytic influence of nanoparticles on the oxidation of amino acids with the variation of pH in working media. Bimetallic nanohybrids of palladium, silver, and gold (e.g., Pd/Ag and Pd/Au nanoparticles) were processed using organofunctionalized alkoxysilanes (3- aminopropyltrimethoxysilane (3-APTMS) and 2-(3,4-epoxycyclohexyl) ethyltrimethoxysilane (EETMOS)) via a sequential reduction pathway. Transmission electron microscopy (TEM) demonstrated the role of the alkoxysilanes in determining the size of the nanoparticles and the distribution of metals in the core-shell configuration. The cluster-like morphology of PdNPs was remodeled to form bimetallic nanomaterials (Pd- AuNPs and Pd-AgNPs) with a core-shell structure. Enhancement in the electrooxidation behavior was shown to depend on the nanomaterial and the pH of the medium. The Pd- AgNPs modified electrode exhibited high sensitivity and selectivity, with characteristic amplification in cathodic peak current at lower oxidation potentials (0.659 V, 0.782 V, and 0.890 V at pH values 4, 7, and 9, respectively) due to its greater stability. Differential pulse voltammetric (DPV) scans were recorded over a wide range of concentrations from 0.1 μM to 1000μM; the Pd-AgNPs modified electrode showed the lowest limit of detection of 0.1μM at pH 4, 0.5 μM at pH 7, and 0.5 μM at pH 9.}, number={46-47}, journal={MRS ADVANCES}, author={Pandey, P. C. and Shukla, Shubhangi and Pandey, Govind and Narayan, Roger J.}, year={2020}, pages={2429–2444} }
 @article{nguyen_goering_skoog_narayan_2020, title={Physical characterization and in vitro evaluation of 3D printed hydroxyapatite, tricalcium phosphate, zirconia, alumina, and SiAlON structures made by lithographic ceramic manufacturing}, volume={5}, ISSN={["2059-8521"]}, DOI={10.1557/adv.2020.229}, abstractNote={In this study, lithographic ceramic manufacturing was used to create solid chips out of hydroxyapatite, tricalcium phosphate, zirconia, alumina, and SiAlON ceramic. X-ray powder diffraction of each material confirmed that the chips were crystalline, with little amorphous character that could result from remaining polymeric binder, and were composed entirely out of the ceramic feedstock. Surface morphologies and roughnesses were characterized using atomic force microscopy. Human bone marrow stem cells cultured with osteogenic supplements on each material type expressed alkaline phosphatase levels, an early marker of osteogenic differentiation, on par with cells cultured on a glass control. However, cells cultured on the tricalcium phosphate-containing material expressed lower levels of ALP suggesting that osteoinduction was impaired on this material. Further analyses should be conducted with these materials to identify underlying issues of the combination of material and analysis method.}, number={46-47}, journal={MRS ADVANCES}, author={Nguyen, Alexander K. and Goering, Peter L. and Skoog, Shelby A. and Narayan, Roger J.}, year={2020}, pages={2419–2428} }
 @article{pandey_pandey_narayan_2021, title={Polyethylenimine-mediated controlled synthesis of Prussian blue-gold nanohybrids for biomedical applications}, volume={36}, ISSN={["1530-8022"]}, DOI={10.1177/0885328220975575}, abstractNote={ We report on polyethylenimine (PEI)-mediated synthesis of Prussian blue nanoparticles (PBNPs) and gold nanoparticles (AuNPs); the formation of PBNP-AuNP nanohybrids with a remarkable change in Prussian blue character as a function of gold cation concentration was also considered. It was shown that PEI-protected polycrystalline PBNPs can be synthesized in an acidic medium from the precursor potassium ferricyanide [K3Fe(CN)6] at 60 °C. Since PEI also enables the controlled formation of gold nanoparticles (AuNPs) in the presence of formaldehyde under ambient conditions, nanohybrids of PBNPs and AuNPs were prepared. The formation of AuNPs was recorded over a wide range of PEI concentrations, which allowed control over polymeric cation capping of the AuNPs. PEI concentration-dependent enhancement/quenching of fluorescence/resonance Rayleigh scattering was useful for non-enzymatic detection of serum glucose levels. The resonance Rayleigh scattering intensity of PBNPs was several-fold higher than that of AuNPs and acted as a potent quencher of fluorescence. At an optimal concentration of PEI, AuNPs allowed an increase in the fluorescence signal as function of glucose concentration; the quenching ability of PB was demonstrated to be a function of the glucose concentration. This method is efficient for fast glucose sensing and offers a wider linear dynamic range, 0–10 mM, which is useful for non-enzymatic detection of serum glucose levels. }, number={1}, journal={JOURNAL OF BIOMATERIALS APPLICATIONS}, author={Pandey, Prem and Pandey, Govind and Narayan, Roger}, year={2021}, month={Jul}, pages={26–35} }
 @article{tabish_narayan_edirisinghe_2020, title={Rapid and label-free detection of COVID-19 using coherent anti-Stokes Raman scattering microscopy}, volume={10}, ISSN={["2159-6867"]}, DOI={10.1557/mrc.2020.81}, abstractNote={From the 1918 influenza pandemic (H1N1) until the recent 2019 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, no efficient diagnostic tools have been developed for sensitive identification of viral pathogens. Rigorous, early, and accurate detection of viral pathogens is not only linked to preventing transmission but also to timely treatment and monitoring of drug resistance. Reverse transcription-polymerase chain reaction (RT-PCR), the gold standard method for microbiology and virology testing, suffers from both false-negative and false-positive results arising from the detection limit, contamination of samples/templates, exponential DNA amplification, and variation of viral ribonucleic acid sequences within a single individual during the course of the infection. Rapid, sensitive, and label-free detection of SARS-CoV-2 can provide a first line of defense against the current pandemic. A promising technique is non-linear coherent anti-Stokes Raman scattering (CARS) microscopy, which has the ability to capture rich spatiotemporal structural and functional information at a high acquisition speed in a label-free manner from a biological system. Raman scattering is a process in which the distinctive spectral signatures associated with light-sample interaction provide information on the chemical composition of the sample. In this prospective, we briefly discuss the development and future prospects of CARS for real-time multiplexed label-free detection of SARS-CoV-2 pathogens.}, number={4}, journal={MRS COMMUNICATIONS}, author={Tabish, Tanveer A. and Narayan, Roger J. and Edirisinghe, Mohan}, year={2020}, month={Dec}, pages={566–572} }
 @misc{zhang_cristescu_chrisey_narayan_2020, title={Solvent-based Extrusion 3D Printing for the Fabrication of Tissue Engineering Scaffolds}, volume={6}, ISBN={2424-8002}, DOI={10.18063/ijb.v6i1.211}, abstractNote={Three-dimensional (3D) printing has been emerging as a new technology for scaffold fabrication to overcome the problems associated with the undesirable microstructure associated with the use of traditional methods. Solvent-based extrusion (SBE) 3D printing is a popular 3D printing method, which enables incorporation of cells during the scaffold printing process. The scaffold can be customized by optimizing the scaffold structure, biomaterial, and cells to mimic the properties of natural tissue. However, several technical challenges prevent SBE 3D printing from translation to clinical use, such as the properties of current biomaterials, the difficulties associated with simultaneous control of multiple biomaterials and cells, and the scaffold-to-scaffold variability of current 3D printed scaffolds. In this review paper, a summary of SBE 3D printing for tissue engineering (TE) is provided. The influences of parameters such as ink biomaterials, ink rheological behavior, crosslinking mechanisms, and printing parameters on scaffold fabrication are considered. The printed scaffold structure, mechanical properties, degradation, and biocompatibility of the scaffolds are summarized. It is believed that a better understanding of the scaffold fabrication process and assessment methods can improve the functionality of SBE-manufactured 3D printed scaffolds.}, number={1}, journal={INTERNATIONAL JOURNAL OF BIOPRINTING}, author={Zhang, Bin and Cristescu, Rodica and Chrisey, Douglas B. and Narayan, Roger J.}, year={2020}, pages={28–42} }
 @article{pandey_katyal_pandey_narayan_2020, title={Synthesis of self-assembled siloxane-polyindole-gold nanoparticle polymeric nanofluid for biomedical membranes}, volume={10}, ISSN={["2159-6867"]}, DOI={10.1557/mrc.2020.50}, abstractNote={In this paper, the Lewis base character of 3-aminopropyltrimethoxysilane (3-APTMS), an imine derivative of siloxane, and an indole monomer were shown to enable the reduction of gold cations in acetone. The Lewis acid–base adduct of indole monomers and gold formed a polyindole–gold nanoparticle sol. Similarly, the Lewis acid–base adduct of 3-APTMS and gold enabled the formation of gold nanoparticles in the presence of acetone. The polyindole–gold nanoparticle sol and siloxane–gold nanoparticles underwent self-assembly into a polymeric nanofluid that was suitable for casting membranes. The use of these membranes as a potentiometric ion sensor for both cations and anions was considered; a common nonspecific ion exchange molecule, sodium tetraphenylborate, and the polymeric nanofluid were used to prepare an anion sensor and a cation sensor.}, number={3}, journal={MRS COMMUNICATIONS}, author={Pandey, Prem C. and Katyal, Naman and Pandey, Govind and Narayan, Roger J.}, year={2020}, month={Sep}, pages={482–486} }
 @article{nguyen_goering_elespuru_das_narayan_2020, title={The Photoinitiator Lithium Phenyl (2,4,6-Trimethylbenzoyl) Phosphinate with Exposure to 405 nm Light Is Cytotoxic to Mammalian Cells but Not Mutagenic in Bacterial Reverse Mutation Assays}, volume={12}, ISSN={["2073-4360"]}, DOI={10.3390/polym12071489}, abstractNote={Lithium phenyl (2,4,6-trimethylbenzoyl) phosphinate (LAP) is a free radical photo-initiator used to initiate free radical chain polymerization upon light exposure, and is combined with gelatin methacryloyl (GelMA) to produce a photopolymer used in bioprinting. The free radicals produced under bioprinting conditions are potentially cytotoxic and mutagenic. Since these photo-generated free radicals are highly-reactive but short-lived, toxicity assessments should be conducted with light exposure. In this study, photorheology determined that 10 min exposure to 9.6 mW/cm2 405 nm light from an LED light source fully crosslinked 10 wt % GelMA with >3.4 mmol/L LAP, conditions that were used for subsequent cytotoxicity and mutagenicity assessments. These conditions were cytotoxic to M-1 mouse kidney collecting duct cells, a cell type susceptible to lithium toxicity. Exposure to ≤17 mmol/L (0.5 wt %) LAP without light was not cytotoxic; however, concurrent exposure to ≥3.4 mmol/L LAP and light was cytotoxic. No condition of LAP and/or light exposure evaluated was mutagenic in bacterial reverse mutation assays using S. typhimurium strains TA98, TA100 and E. coli WP2 uvrA. These data indicate that the combination of LAP and free radicals generated from photo-excited LAP is cytotoxic, but mutagenicity was not observed in bacteria under typical bioprinting conditions.}, number={7}, journal={POLYMERS}, author={Nguyen, Alexander K. and Goering, Peter L. and Elespuru, Rosalie K. and Das, Srilekha Sarkar and Narayan, Roger J.}, year={2020}, month={Jul} }
 @article{narayan_2020, title={Unified model of field assisted sintering and related phenomena}, volume={176}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2019.09.012}, abstractNote={Critical elements of the model are temperature-assisted generation of free electrons, field-assisted transport and trapping of free electrons to generate defects, segregation of defects to dislocations and grain boundaries through elastic and electrostatic interactions, and creation of percolation paths along grain boundaries. There is a critical electric field required to establish these percolation paths, where free electrons-defects-free electrons bootstrapping avalanche occurs, leading to selective Joule heating and localized melting to achieve near theoretical density. The critical field for percolation is a function of microstructure, temperature and time (incubation period), and it is much higher for single crystals than polycrystalline materials.}, journal={SCRIPTA MATERIALIA}, author={Narayan, J.}, year={2020}, month={Feb}, pages={117–121} }
 @article{nguyen_narayan_shafiee_2019, title={3D Printing in the Biomedical Field}, DOI={10.1016/B978-0-12-801238-3.99875-1}, abstractNote={Recent advances in materials and computing technologies have resulted in a large progress in the use of 3D printing for biomedical applications. 3D printing encompasses multiple fabrication technologies and materials ranging from extrusion to laser processing. Additionally, materials such as live cells or metal powders can be processed for applications ranging from soft tissue to rigid prosthetics. Printers are being employed different aspects of medical field such as tissue engineering, surgical planning model fabrication, medical training, and education. Herein, we overview the applications of printers for biomedical purposes.}, journal={ENCYCLOPEDIA OF BIOMEDICAL ENGINEERING, VOL 2}, author={Nguyen, Alexander K. and Narayan, Roger J. and Shafiee, Ashkan}, year={2019}, pages={275–280} }
 @misc{pandey_shukla_skoog_boehm_narayan_2019, title={Current Advancements in Transdermal Biosensing and Targeted Drug Delivery}, volume={19}, ISSN={["1424-8220"]}, DOI={10.3390/s19051028}, abstractNote={In this manuscript, recent advancements in the area of minimally-invasive transdermal biosensing and drug delivery are reviewed. The administration of therapeutic entities through the skin is complicated by the stratum corneum layer, which serves as a barrier to entry and retards bioavailability. A variety of strategies have been adopted for the enhancement of transdermal permeation for drug delivery and biosensing of various substances. Physical techniques such as iontophoresis, reverse iontophoresis, electroporation, and microneedles offer (a) electrical amplification for transdermal sensing of biomolecules and (b) transport of amphiphilic drug molecules to the targeted site in a minimally invasive manner. Iontophoretic delivery involves the application of low currents to the skin as well as the migration of polarized and neutral molecules across it. Transdermal biosensing via microneedles has emerged as a novel approach to replace hypodermic needles. In addition, microneedles have facilitated minimally invasive detection of analytes in body fluids. This review considers recent innovations in the structure and performance of transdermal systems.}, number={5}, journal={SENSORS}, author={Pandey, Prem C. and Shukla, Shubhangi and Skoog, Shelby A. and Boehm, Ryan D. and Narayan, Roger J.}, year={2019}, month={Mar} }
 @article{baino_marchi_narayan_2019, title={Editorial note to the Special Issue "Advances in Bioceramics"}, volume={16}, ISSN={["1744-7402"]}, DOI={10.1111/ijac.13266}, abstractNote={International Journal of Applied Ceramic TechnologyVolume 16, Issue 5 p. 1752-1752 SPECIAL ISSUE ARTICLE Editorial note to the Special Issue “Advances in Bioceramics” Francesco Baino, Corresponding Author Francesco Baino francesco.baino@polito.it orcid.org/0000-0001-8860-0497 Institute of Materials Physics and Engineering, Department of Applied Science and Technology, Politecnico di Torino, Torino, ItalyMembers of the American Ceramic Society (ACerS). Correspondence Francesco Baino, Institute of Materials Physics and Engineering, Department of Applied Science and Technology, Politecnico di Torino, Torino, Italy. Email: francesco.baino@polito.itSearch for more papers by this authorJuliana Marchi, Juliana Marchi orcid.org/0000-0002-0663-0463 Center for Natural Sciences and Humanities, Federal University do ABC, Santo André, BrazilSearch for more papers by this authorRoger Narayan, Roger Narayan Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC, USAMembers of the American Ceramic Society (ACerS).Search for more papers by this author Francesco Baino, Corresponding Author Francesco Baino francesco.baino@polito.it orcid.org/0000-0001-8860-0497 Institute of Materials Physics and Engineering, Department of Applied Science and Technology, Politecnico di Torino, Torino, ItalyMembers of the American Ceramic Society (ACerS). Correspondence Francesco Baino, Institute of Materials Physics and Engineering, Department of Applied Science and Technology, Politecnico di Torino, Torino, Italy. Email: francesco.baino@polito.itSearch for more papers by this authorJuliana Marchi, Juliana Marchi orcid.org/0000-0002-0663-0463 Center for Natural Sciences and Humanities, Federal University do ABC, Santo André, BrazilSearch for more papers by this authorRoger Narayan, Roger Narayan Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC, USAMembers of the American Ceramic Society (ACerS).Search for more papers by this author First published: 29 April 2019 https://doi.org/10.1111/ijac.13266 Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume16, Issue5Special Topic: Advances in BioceramicsSeptember/October 2019Pages 1752-1752 RelatedInformation}, number={5}, journal={INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY}, author={Baino, Francesco and Marchi, Juliana and Narayan, Roger}, year={2019}, month={Sep}, pages={1752–1752} }
 @article{moatti_sachan_cooper_narayan_2019, title={Electrical Transition in Isostructural VO2 Thin-Film Heterostructures}, volume={9}, ISSN={2045-2322}, url={http://dx.doi.org/10.1038/S41598-019-39529-Z}, DOI={10.1038/s41598-019-39529-z}, abstractNote={AbstractControl over the concurrent occurrence of structural (monoclinic to tetragonal) and electrical (insulator to the conductor) transitions presents a formidable challenge for VO2-based thin film devices. Speed, lifetime, and reliability of these devices can be significantly improved by utilizing solely electrical transition while eliminating structural transition. We design a novel strain-stabilized isostructural VO2 epitaxial thin-film system where the electrical transition occurs without any observable structural transition. The thin-film heterostructures with a completely relaxed NiO buffer layer have been synthesized allowing complete control over strains in VO2 films. The strain trapping in VO2 thin films occurs below a critical thickness by arresting the formation of misfit dislocations. We discover the structural pinning of the monoclinic phase in (10 ± 1 nm) epitaxial VO2 films due to bandgap changes throughout the whole temperature regime as the insulator-to-metal transition occurs. Using density functional theory, we calculate that the strain in monoclinic structure reduces the difference between long and short V-V bond-lengths (ΔV−V) in monoclinic structures which leads to a systematic decrease in the electronic bandgap of VO2. This decrease in bandgap is additionally attributed to ferromagnetic ordering in the monoclinic phase to facilitate a Mott insulator without going through the structural transition.}, number={1}, journal={Scientific Reports}, publisher={Springer Science and Business Media LLC}, author={Moatti, Adele and Sachan, Ritesh and Cooper, Valentino R and Narayan, Jagdish}, year={2019}, month={Feb} }
 @article{miller_moorman_boehm_wolfley_chavez_baca_ashley_brener_narayan_polsku_2019, title={Fabrication of Hollow Metal Microneedle Arrays Using a Molding and Electroplating Method}, volume={4}, ISSN={["2059-8521"]}, DOI={10.1557/adv.2019.147}, abstractNote={The need for hollow microneedle arrays is important for both drug delivery and wearable sensor applications; however, their fabrication poses many challenges. Hollow metal microneedle arrays residing on a flexible metal foil substrate were created by combining additive manufacturing, micromolding, and electroplating approaches in a process we refer to as electromolding. A solid microneedle with inward facing ledge was fabricated with a two photon polymerization (2PP) system utilizing laser direct write (LDW) and then molded with polydimethylsiloxane. These molds were then coated with a seed layer of Ti/Au and subsequently electroplated with pulsed deposition to create hollow microneedles. An inward facing ledge provided a physical blocking platform to restrict deposition of the metal seed layer for creation of the microneedle bore. Various ledge sizes were tested and showed that the resulting seed layer void could be controlled via the ledge length. Mechanical properties of the PDMS mold was adjusted via the precursor ratio to create a more ductile mold that eliminated tip damage to the microneedles upon removal from the molds. Master structures were capable of being molded numerous times and molds were able to be reused. SEM/EDX analysis showed that trace amounts of the PDMS mold were transferred to the metal microneedle upon removal. The microneedle substrate showed a degree of flexibility that withstood over 100 cycles of bending from side to side without damaging. Microneedles were tested for their fracture strength and were capable of puncturing porcine skin and injecting a dye.}, number={24}, journal={MRS ADVANCES}, author={Miller, Philip R. and Moorman, Matthew and Boehm, Ryan D. and Wolfley, Steven and Chavez, Victor and Baca, Justin T. and Ashley, Carlee and Brener, Igal and Narayan, Roger J. and Polsku, Ronen}, year={2019}, pages={1417–1426} }
 @article{bhaumik_narayan_2019, title={Formation and characterization of nano- and microstructures of twinned cubic boron nitride}, volume={21}, ISSN={1463-9076 1463-9084}, url={http://dx.doi.org/10.1039/C8CP04592E}, DOI={10.1039/c8cp04592e}, abstractNote={The controlled growth of phase-pure nano- and microstructures of twinned c-BN will have tremendous impact on electrical and mechanical devices.}, number={4}, journal={Physical Chemistry Chemical Physics}, publisher={Royal Society of Chemistry (RSC)}, author={Bhaumik, Anagh and Narayan, Jagdish}, year={2019}, pages={1700–1710} }
 @misc{machekposhti_mohaved_narayan_2019, title={Inkjet dispensing technologies: recent advances for novel drug discovery}, volume={14}, ISSN={["1746-045X"]}, DOI={10.1080/17460441.2019.1567489}, abstractNote={ABSTRACT Introduction: Inkjet-dispensing printing is a promising additive manufacturing method for pharmaceutical applications such as drug discovery. The unique advantages of this technology, including low cost, programmability, high resolution, high throughput, high speed, and biocompatibility, may reduce the financial resources needed to discover new drug candidates. Sophisticated and miniaturized assays have been developed to accomplish drug discovery and drug screening using modern inkjet dispensing printers. Areas covered: This paper reviews recent advancements in the field of inkjet printer technology for drug discovery. Various types of inkjet printers and their recent use for the drug discovery are summarized; physical and biological limitations of this technology are also examined. Furthermore, typical inks used in the inkjet printing technology are introduced. Expert opinion: Inkjet bioprinting technology is a promising tool for many biological and pharmaceutical applications. Several bottlenecks associated with this technology need to be addressed before commercialization. For example, sophisticated inks need to be synthesized to meet both biological and engineering restrictions. Further progress of parallel technologies will enhance the performance and functionality of the printers. It is also worth emphasizing that inkjet printing technologies must meet the requirement of regulatory agencies (e.g. the US Food & Drug Administration) for commercialization by the pharmaceutical industry.}, number={2}, journal={EXPERT OPINION ON DRUG DISCOVERY}, author={Machekposhti, Sina Azizi and Mohaved, Saeid and Narayan, Roger J.}, year={2019}, month={Feb}, pages={101–113} }
 @article{nguyen_yang_bryant_li_joice_werbovetz_narayan_2019, title={Microneedle-Based Delivery of Amphotericin B for Treatment of Cutaneous Leishmaniasis}, volume={21}, ISSN={["1572-8781"]}, DOI={10.1007/s10544-018-0355-8}, abstractNote={Current therapeutic options against cutaneous leishmaniasis are plagued by several weaknesses. The effective topical delivery of an antileishmanial drug would be useful in treating some forms of cutaneous leishmaniasis. Toward this end, a microneedle based delivery approach for the antileishmanial drug amphotericin B was investigated in murine models of both New World (Leishmania mexicana) and Old World (Leishmania major) infection. In the L. mexicana model, ten days of treatment began on day 35 post infection, when the area of nodules averaged 9–15 mm2. By the end of the experiment, a significant difference in nodule area was observed for all groups receiving topical amphotericin B at 25 mg/kg/day after application of microneedle arrays of 500, 750, and 1000 μM in nominal length compared to the group that received this dose of topical amphotericin B alone. In the L. major model, ten days of treatment began on day 21 post infection when nodule area averaged 51–65 mm2 in the groups. By the end of the experiment, there was no difference in nodule area between the group receiving 25 mg/kg of topical amphotericin B after microneedle application and any of the non-AmBisome groups. These results show the promise of topical delivery of amphotericin B via microneedles in treating relatively small nodules caused by L. mexicana. These data also show the limitations of the approach against a disseminated L. major infection. Further optimization of microneedle delivery is needed to fully exploit this strategy for cutaneous leishmaniasis treatment.}, number={1}, journal={BIOMEDICAL MICRODEVICES}, author={Nguyen, Alexander K. and Yang, Kai-Hung and Bryant, Kelsey and Li, Junan and Joice, April C. and Werbovetz, Karl A. and Narayan, Roger J.}, year={2019}, month={Mar} }
 @article{kostecki_zhang_el habti_arman_hutchinson_tricker_fleury_narayan_ebendorff-heidepriem_2019, title={Optical Fiber Based In-Vivo Oxidative Stress Biosensor}, volume={11202}, ISSN={["1996-756X"]}, DOI={10.1117/12.2539920}, abstractNote={Oxygen metabolism is a necessary process that takes place in animals and plants. Our cells and plant cells produce free radicals known as reactive oxygen species (ROS) continuously as a byproduct of oxygen metabolism and reaction to various environmental stresses, which must be normalized to avoid oxidative stress. Oxidative stress is intimately linked to cellular energy balance and occurs when there’s an imbalance between production and accumulation of ROS in cells and tissues and the ability of a biological system to keep in a redox steady state. We show preliminary results of an optical fiber based reversible in-vivo biosensor for understanding redox balance within living systems. The biosensor measured protein carbonyls (a marker of oxygen metabolism and oxidative stress) in pig-skin, live mouse, and wheat plant.}, journal={BIOPHOTONICS AUSTRALASIA 2019}, author={Kostecki, Roman and Zhang, Bin and El Habti, Abdeljalil and Arman, Azim and Hutchinson, Mark R. and Tricker, Penny J. and Fleury, Delphine and Narayan, Roger J. and Ebendorff-Heidepriem, Heike}, year={2019} }
 @misc{shafiee_ghadiri_ramesh_kengla_kassis_calvert_williams_khademhosseini_narayan_forgacs_et al._2019, title={Physics of bioprinting}, volume={6}, ISSN={["1931-9401"]}, DOI={10.1063/1.5087206}, abstractNote={Bioprinters are being extensively used for different applications in life sciences and medicine in general and more specifically in regenerative medicine, tissue, and organ fabrication. The technology has matured from its purely academic origin owing to the involvement of materials science, engineering, biology, and physics, as well as commercial entities. Nevertheless, despite the progress in the science and the understanding of the mechanisms underlying the various bioprinting technologies, further efforts are needed to develop more quantitative strategies. In particular, predictive modeling is necessary to optimize the printing parameters and thus enhance the quality of the final products. Here, we review the physics that underpins the most commonly employed approaches, such as extrusion, laser-based, and inkjet bioprinting. We provide an overview of the relevant parameters, their inter-relationships, and the equations that govern the various printing processes and thus allow for their optimization. We present our perspective on the field and views on future strategies for its further advancement. Our intention with this review is to provide the practitioners of bioprinting with additional tools to enhance the quantitative aspects of their work and move the technology beyond its early, mostly “trial and error” character.}, number={2}, journal={APPLIED PHYSICS REVIEWS}, author={Shafiee, Ashkan and Ghadiri, Elham and Ramesh, Haripriya and Kengla, Carlos and Kassis, Jareer and Calvert, Paul and Williams, David and Khademhosseini, Ali and Narayan, Roger and Forgacs, Gabor and et al.}, year={2019}, month={Jun} }
 @article{akouala_kumar_punugupati_reynolds_reynolds_mily_maria_narayan_hunte_2019, title={Planar Hall effect and anisotropic magnetoresistance in semiconducting and conducting oxide thin films}, volume={125}, ISSN={0947-8396 1432-0630}, url={http://dx.doi.org/10.1007/S00339-019-2592-Y}, DOI={10.1007/s00339-019-2592-y}, number={5}, journal={Applied Physics A}, publisher={Springer Science and Business Media LLC}, author={Akouala, Christer R. and Kumar, Raj and Punugupati, Sandhyarani and Reynolds, C. Lewis and Reynolds, Judith G. and Mily, Edward J. and Maria, Jon-Paul and Narayan, Jagdish and Hunte, Frank}, year={2019}, month={Apr} }
 @article{nguyen_goering_olenick_olenick_narayan_2019, title={Sintered Tape-cast 3YSZ Supports Human Bone Marrow Derived Stem Cell Osteogenic Differentiation}, volume={4}, ISSN={["2059-8521"]}, DOI={10.1557/adv.2019.335}, abstractNote={Sintered tape-cast yttria-stabilized zirconia (YSZ) was evaluated for its elemental composition, crystal structure, and imaged with atomic force microscopy (AFM) and scanning electron microscopy (SEM). Human bone marrow stem cells (hBMSC) were cultured on the ceramic and differentiated into the osteoblast lineage; alkaline phosphatase (ALP) activity was tracked as a differentiation marker. The YSZ was composed of purely tetragonal grains with a median equivalent circular diameter of 283 nm. Zirconium, yttrium, oxygen, and adventitious carbon was detected on the substrate with no other elements in significant quantities detected. YSZ samples had an RMS roughness value of 27 nm, elastic modulus of 206 ± 14 GPa, and hardness of 14 ± 2 GPa. hBMSC were observed to attach and proliferate on the YSZ surfaces and had significantly increased ALP versus the undifferentiated control cultured on glass. This method for producing a YSZ ceramic yields a typical material of this type and supports attachment and differentiation of hBMSC; thus, making it useful as a bone implant material.}, number={46-47}, journal={MRS ADVANCES}, author={Nguyen, Alexander K. and Goering, Peter L. and Olenick, John A. and Olenick, Kathy and Narayan, Roger J.}, year={2019}, pages={2541–2549} }
 @article{bhaumik_narayan_2019, title={Structure–property correlations in phase-pure B-doped Q-carbon high-temperature superconductor with a record Tc = 55 K}, volume={11}, ISSN={2040-3364 2040-3372}, url={http://dx.doi.org/10.1039/C9NR00562E}, DOI={10.1039/c9nr00562e}, abstractNote={The discovery of record BCS Tc = 55 K superconductivity in phase-pure B-doped Q-carbon will provide the pathway to achieve room-temperature superconductivity.}, number={18}, journal={Nanoscale}, publisher={Royal Society of Chemistry (RSC)}, author={Bhaumik, Anagh and Narayan, Jagdish}, year={2019}, pages={9141–9154} }
 @article{nguyen_goering_reipa_narayan_2019, title={Toxicity and photosensitizing assessment of gelatin methacryloyl-based hydrogels photoinitiated with lithium phenyl-2,4,6-trimethylbenzoylphosphinate in human primary renal proximal tubule epithelial cells}, volume={14}, ISSN={["1559-4106"]}, DOI={10.1116/1.5095886}, abstractNote={Gelatin methacryloyl (GelMA) and lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) photoinitiator are commonly used in combination to produce a photosensitive polymer but there are concerns that must be addressed: the presence of unreacted monomer is well known to be cytotoxic, and lithium salts are known to cause acute kidney injury. In this study, acellular 10% GelMA hydrogels cross-linked with different LAP concentrations and cross-linking illumination times were evaluated for their cytotoxicity, photosensitizing potential, and elastic moduli. Alamar Blue and CyQuant Direct Cell viability assays were performed on human primary renal proximal tubule epithelial cells (hRPTECs) exposed to extracts of each formulation. UV exposure during cross-linking was not found to affect extract cytotoxicity in either assay. LAP concentration did not affect extract cytotoxicity as determined by the Alamar Blue assay but reduced hRPTEC viability in the CyQuant Direct cell assay. Photocatalytic activity of formulation extracts toward NADH oxidation was used as a screening method for photosensitizing potential; longer UV exposure durations yielded extracts with less photocatalytic activity. Finally, elastic moduli determined using nanoindentation was found to plateau to approximately 20–25 kPa after exposure to 342 mJ/cm2 at 2.87 mW of UV-A exposure regardless of LAP concentration. LAP at concentrations commonly used in bioprinting (<0.5% w/w) was not found to be cytotoxic although the differences in cytotoxicity evaluation determined from the two viability assays imply cell membrane damage and should be investigated further. Complete cross-linking of all formulations decreased photocatalytic activity while maintaining predictable final elastic moduli.}, number={2}, journal={BIOINTERPHASES}, author={Nguyen, Alexander K. and Goering, Peter L. and Reipa, Vytas and Narayan, Roger J.}, year={2019} }
 @article{bhaumik_sachan_narayan_2019, title={Tunable charge states of nitrogen-vacancy centers in diamond for ultrafast quantum devices}, volume={142}, ISSN={0008-6223}, url={http://dx.doi.org/10.1016/J.CARBON.2018.10.084}, DOI={10.1016/j.carbon.2018.10.084}, abstractNote={A prerequisite condition for next-generation quantum sensing, communication, and computing is the precise modulation of the charge states of nitrogen-vacancy (NV) centers in diamond. We have achieved tuning of these centers in highly concentrated NV-diamonds using photons, phonons, and electrons. These NV-diamonds are synthesized employing a unique nanosecond laser processing technique which results in ultrafast melting and subsequent quenching of nitrogen-doped molten carbon films. Substitutional nitrogen atoms and vacancies are incorporated into diamond during rapid liquid-phase growth, where dopant concentrations can exceed thermodynamic solubility limits through solute trapping. This ultrafast synthesis technique generates fewer surface traps thereby forming ∼75% NV− centers at room-temperature, which are optically and magnetically distinct as compared to NV0 centers. We dramatically increase the NV− concentration in NV-diamonds by ∼53% with decreasing temperature from 300 to 80 K. With negative electrical biasing, the Fermi level in NV-diamond rises and crosses the NV0/- level, thereby promoting an exponential conversion of NV0 to NV− centers. We have also photonically enhanced the photoluminescence signal from NV− centers, thereby ascertaining the conversion of NV0 into NV− via absorption of electrons (excited by 532 nm photons) from the valence band in NV-diamond. These NV-centers in diamonds also reveal large excitation lifetime, which ultimately leads to ∼65% quantum efficiency at room-temperature. With these results, we believe that the precise tuning of charge states in these uniquely prepared highly concentrated NV-diamonds will lead to superior quantum devices.}, journal={Carbon}, publisher={Elsevier BV}, author={Bhaumik, Anagh and Sachan, Ritesh and Narayan, Jagdish}, year={2019}, month={Feb}, pages={662–672} }
 @article{miar_shafiee_guda_narayan_2018, title={Additive Manufacturing for Tissue Engineering}, ISBN={["978-3-319-45443-6"]}, DOI={10.1007/978-3-319-45444-3_2}, journal={3D PRINTING AND BIOFABRICATION}, author={Miar, Solaleh and Shafiee, Ashkan and Guda, Teja and Narayan, Roger}, year={2018}, pages={3–54} }
 @misc{skoog_kumar_narayan_goering_2018, title={Biological responses to immobilized microscale and nanoscale surface topographies}, volume={182}, ISSN={["0163-7258"]}, DOI={10.1016/j.pharmthera.2017.07.009}, abstractNote={Cellular responses are highly influenced by biochemical and biomechanical interactions with the extracellular matrix (ECM). Due to the impact of ECM architecture on cellular responses, significant research has been dedicated towards developing biomaterials that mimic the physiological environment for design of improved medical devices and tissue engineering scaffolds. Surface topographies with microscale and nanoscale features have demonstrated an effect on numerous cellular responses, including cell adhesion, migration, proliferation, gene expression, protein production, and differentiation; however, relationships between biological responses and surface topographies are difficult to establish due to differences in cell types and biomaterial surface properties. Therefore, it is important to optimize implant surface feature characteristics to elicit desirable biological responses for specific applications. The goal of this work was to review studies investigating the effects of microstructured and nanostructured biomaterials on in vitro biological responses through fabrication of microscale and nanoscale surface topographies, physico-chemical characterization of material surface properties, investigation of protein adsorption dynamics, and evaluation of cellular responses in specific biomedical applications.}, journal={PHARMACOLOGY & THERAPEUTICS}, author={Skoog, Shelby A. and Kumar, Girish and Narayan, Roger J. and Goering, Peter L.}, year={2018}, month={Feb}, pages={33–55} }
 @article{narayan_2018, title={Editorial}, volume={1}, ISSN={2573-802X 2573-802X}, url={http://dx.doi.org/10.1002/MDS3.10009}, DOI={10.1002/MDS3.10009}, abstractNote={The field of medical devices and sensors is rapidly expanding. For example, the worldwide market for medical devices is growing at a compound annual growth rate of 5.3% and will reach a size of $674.5 billion by 2022 (Laxmi, 2018). The field will continue its growth over this century due to ageing populations in China, Japan, Europe and the United States since older individuals utilize medical devices and surgical procedures at higher rates than their younger counterparts (Wilson, 2012). New devices are needed for monitoring and treatment of medical conditions that commonly affect ageing populations. For example, the number of individuals with diabetes is expected to significantly grow over the coming years. The number of individuals with diabetes mellitus worldwide is expected to grow from 220 million to 366 million by the year 2030 (McWilliams, 2011). There are 22 million individuals with cancer worldwide; the most common forms of cancer include lung, colorectal, stomach, breast and cervical cancer (McWilliams, 2011). Significant growth in the number of individuals with cardiovascular disease and kidney disorders, two conditions associated with the adoption of Western lifestyle, is also anticipated (Joshi, 2014). Nanobiotechnology may be used to create new drugs (e.g., liposome-, nanocrystal- and nanoparticle-based drugs) and diagnostic tools (e.g., nanoparticle- and quantum dot-based tools) for management of these conditions (Bergin, 2011). For example, nanoparticles and other types of nanomaterials are being considered for use in imaging, flow cytometry-based cell analysis and microarray-based genomics. Companies and governmental agencies have commercialized nanopore technology for DNA sequencing. Materials are being developed for lab on a chip (e.g., PCR on a chip) devices, which may facilitate detection of cancer cells. The market for nanobiotechnology-based healthcare products is growing at a compound annual growth rate of 8.7% and will reach a size of 29 billion dollars in 2016. Companies such as GE Healthcare and Siemens Medical are making significant investments in the use of nanotechnology for medical applications. The development of coatings to prevent restenosis (blockage) or cardiac stents, increase lubricity of catheters and prevent degradation of orthopaedic implants is another growing area of medical device research (Wilson, 2012). Eighty per cent of medical devices utilize coated materials; some medical devices contain multiple coatings. The market for surface modification and coating of medical devices reached $8 billion worldwide in 2017. There is also growing interest in the development of novel materials and devices for controlled release of pharmacologic agents for the treatment of cancer and other chronic medical conditions (Dewan, 2014). For example, liposomes, micelles, dendrimers, DNA-containing structures and biodegradable particles are being developed in academic and industrial laboratories for targeted drug delivery. In addition, novel devices are being created for transdermal delivery of pharmacologic agents that normally cannot cross the skin barrier. Several manufacturers, including AstraZeneca plc, Bayer, Bausch & Lomb and Sanofi, are developing implants for drug delivery. The market for drug delivery materials and devices will reach $8 billion worldwide by 2018. The market for microelectronic implants for neurostimulation, defibrillation, drug delivery, hearing restoration, vision restoration and replacement of cardiac function is growing at a compound annual growth rate of 8.8% and reached a size of 24.8 billion dollars in 2016 (McWilliams, 2011). Current research efforts are underway to incorporate nano-structured sensors and small-size power supplies within medical implants. The development of novel materials for small-scale sensors and the integration of sensors with communication systems are also growing; the global market for sensor technologies in 2014 was estimated to be 8.3 billion US dollars (Wilson, 2010). In addition, the development of novel materials for use as contrast agents, including microbubbles and biomolecule-labelled position emission tomography tracers, is an important area of medical device research (Dewan, 2013). The use of medical devices for patient monitoring, surgery and medical imaging in Brazil, China, India, Mexico and other developing countries is expected to markedly increase over the coming years (McWilliams, 2010). In 2014, the size of the medical device market in developing countries exceeded 24 billion US dollars. New resources are needed to communicate academic and industrial advances in medical devices and sensors to the global community that studies and uses these technologies. Medical devices and sensors will serve an international audience, including academic researchers, government researchers, medical device manufacturers, regulatory staff and clinicians, by publishing innovations in the science and engineering that underlie these technologies. The journal will disseminate information on recent developments, application-specific testing, clinical translation, commercialization and regulatory issues, to the global medical device community. Some of the research themes of the journal include: The journal will provide comprehensive coverage of the dynamic medical device field via (a) rapid communication articles on exciting research advances, (b) full-length articles that describe research developments in a comprehensive manner, (c) mini-reviews that cover recent progress in research and clinical translation, (d) editorials that express opinions of international thought leaders or (e) case studies that communicate information on academic and industrial breakthroughs. I would like express my gratitude to the staff at John Wiley & Sons for all of their efforts to shepherd this journal from concept to reality. I hope that this publication plays a unique role in the growing biomedical engineering community by providing a venue for cutting-edge information related to innovations in the science and engineering that underlie medical devices and sensors.}, number={1}, journal={Medical Devices & Sensors}, publisher={Wiley}, author={Narayan, Roger}, year={2018}, month={Feb}, pages={e10009} }
 @article{yang_nguyen_goering_sumant_narayan_2018, title={Ultrananocrystalline diamond-coated nanoporous membranes support SK-N-SH neuroblastoma endothelial cell attachment}, volume={8}, ISSN={["2042-8901"]}, DOI={10.1098/rsfs.2017.0063}, abstractNote={Ultrananocrystalline diamond (UNCD) has been demonstrated to have attractive features for biomedical applications and can be combined with nanoporous membranes for applications in drug delivery systems, biosensing, immunoisolation and single molecule analysis. In this study, free-standing nanoporous UNCD membranes with pore sizes of 100 or 400 nm were fabricated by directly depositing ultrathin UNCD films on nanoporous silicon nitride membranes and then etching away silicon nitride using reactive ion etching. Successful deposition of UNCD on the substrate with a novel process was confirmed with Raman spectroscopy, X-ray photoelectron spectroscopy, cross-section scanning electron microscopy (SEM) and transmission electron microscopy. Both sample types exhibited uniform geometry and maintained a clear hexagonal pore arrangement. Cellular attachment of SK-N-SH neuroblastoma endothelial cells was examined using confocal microscopy and SEM. Attachment of SK-N-SH cells onto UNCD membranes on both porous regions and solid surfaces was shown, indicating the potential use of UNCD membranes in biomedical applications such as biosensors and tissue engineering scaffolds.}, number={3}, journal={INTERFACE FOCUS}, author={Yang, Kai-Hung and Nguyen, Alexander K. and Goering, Peter L. and Sumant, Anirudha V. and Narayan, Roger J.}, year={2018}, month={Jun} }
 @article{bouten_ramakrishna_narayan_2017, title={Additive manufacturing for regenerative medicine: Where do we go from here?}, volume={2}, ISSN={2468-4511}, url={http://dx.doi.org/10.1016/J.COBME.2017.07.002}, DOI={10.1016/J.COBME.2017.07.002}, journal={Current Opinion in Biomedical Engineering}, publisher={Elsevier BV}, author={Bouten, Carlijn V.C. and Ramakrishna, Seeram and Narayan, Roger}, year={2017}, month={Jun}, pages={iii-v} }
 @article{yang_narayan_2017, title={Analytical methods for detection of Zika virus}, volume={7}, ISSN={["2159-6867"]}, DOI={10.1557/mrc.2017.20}, abstractNote={Due to the recent outbreak of the Zika virus (ZIKV) in several regions, rapid, and accurate methods to diagnose Zika infection are in demand, particularly in regions that are on the frontline of a ZIKV outbreak. In this paper, three diagnostic methods for ZIKV are considered. Viral isolation is the gold standard for detection; this approach can involve incubation of cell cultures. Serological identification is based on the interactions between viral antigens and immunoglobulin G or immunoglobulin M antibodies; cross-reactivity with other types of flaviviruses can cause reduced specificity with this approach. Molecular confirmation, such as reverse transcription polymerase chain reaction (RT–PCR), involves reverse transcription of RNA and amplification of DNA. Quantitative analysis based on real-time RT–PCR can be undertaken by comparing fluorescence measurements against previously developed standards. A recently developed programmable paper-based detection approach can provide low-cost and rapid analysis. These viral identification and viral genetic analysis approaches play crucial roles in understanding the transmission of ZIKV.}, number={2}, journal={MRS COMMUNICATIONS}, author={Yang, Kai-Hung and Narayan, Roger J.}, year={2017}, month={Jun}, pages={121–130} }
 @article{petrochenko_zheng_casey_bayati_narayan_goering_2017, title={Nanosilver-PMMA composite coating optimized to provide robust antibacterial efficacy while minimizing human bone marrow stromal cell toxicity}, volume={44}, ISSN={0887-2333}, url={http://dx.doi.org/10.1016/J.TIV.2017.07.014}, DOI={10.1016/J.TIV.2017.07.014}, abstractNote={Porous PMMA is a versatile biomaterial with good biocompatibility but high susceptibility to bacterial colonization, which we mitigated by utilizing immobilized antimicrobial silver nanoparticles (AgNPs). A uniform porous thin film was deposited onto silicon wafers by simultaneously ablating PMMA and silver (Ag) using pulsed laser deposition (PLD) optimized for minimal human cell toxicity and antibacterial efficacy. PMMA without Ag became heavily colonized by E. coli in simulated dynamic conditions, while Ag-containing samples prevented all colonization. ICP-MS analysis demonstrated that the amount of leached Ag after 24h under simulated in vivo conditions (with serum media at 37°C and 5% CO2) increased in proportion to film thickness (and total silver content). 10,000, 14,000, and 20,000 laser pulse-deposited films released 0.76, 1.05, and 1.67μg/mL Ag, respectively, after 24h. Human bone marrow stromal cells (hBMSCs) grown directly on 10,000-pulse films (0.76μg/mL Ag released) for 24-h exhibited no cytotoxicity. Exposure to the remaining films produced cytotoxicity, necrosis, and apoptosis detected using flow cytometry. Examining both leachates and direct cell contact allowed us to develop an in vitro cytotoxicity test method and optimize a novel device material and coating to be nontoxic and bactericidal during both potential initial implantation and external use.}, journal={Toxicology in Vitro}, publisher={Elsevier BV}, author={Petrochenko, Peter E. and Zheng, Jiwen and Casey, Brendan J. and Bayati, M. Reza and Narayan, Roger J. and Goering, Peter L.}, year={2017}, month={Oct}, pages={248–255} }
 @article{kim_narayan_lu_jay_2017, title={Neutron-activatable needles for radionuclide therapy of solid tumors}, volume={105}, ISSN={["1552-4965"]}, DOI={10.1002/jbm.a.36185}, abstractNote={AbstractVarious approaches have been undertaken to enhance the delivery of therapeutic agents, including tissue‐killing radionuclides, into solid tumors. Here, we describe the preparation of conical needles composed of Ti and Mo coated by pulsed laser deposition or chemical vapor deposition with elements (Ho and Re) that can readily yield radioactive isotopes following irradiation in a neutron flux. The radioactive needles, whose design were based on solid microneedle arrays used in transdermal drug delivery, can be produced with minimal handling of radioactivity and subsequently inserted into tumors as a means of internal radiation therapy. Ho and Re were specifically chosen because of their large neutron capture cross‐sections as well as the desirable radiotherapeutic properties of the resultant radionuclides. Neutron‐absorbing shields were also developed to prevent the production of unwanted radionuclides after neutron irradiation of the needle base materials. Neutron activation calculations showed that therapeutically significant amounts of radionuclides can be produced for treating solid tumors. Stability studies demonstrated that Re did not leach off the Mo needles. These coated neutron‐activatable needles offer a new approach to internal radiation therapy of tumors that allows precise tailoring of the absorbed radiation dose delivered to the tumor by controlling the coating thickness and the irradiation time. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3273–3280, 2017.}, number={12}, journal={JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A}, author={Kim, Junghyun and Narayan, Roger J. and Lu, Xiuling and Jay, Michael}, year={2017}, month={Dec}, pages={3273–3280} }
 @article{pandey_pandey_narayan_2017, title={Polyethylenimine-mediated synthetic insertion of gold nanoparticles into mesoporous silica nanoparticles for drug loading and biocatalysis}, volume={12}, ISSN={["1559-4106"]}, DOI={10.1116/1.4979200}, abstractNote={Mesoporous silica nanoparticles (MSNPs) have been used as an efficient and safe carrier for drug delivery and biocatalysis. The surface modification of MSNPs using suitable reagents may provide a robust framework in which two or more components can be incorporated to give multifunctional capabilities (e.g., synthesis of noble metal nanoparticles within mesoporous architecture along with loading of a bioactive molecule). In this study, the authors reported on a new synthetic route for the synthesis of gold nanoparticles (AuNPs) within (1) unmodified MSNPs and (2) 3-trihydroxysilylpropyl methylphosphonate-modified MSNPs. A cationic polymer, polyethylenimine (PEI), and formaldehyde were used to mediate synthetic incorporation of AuNPs within MSNPs. The AuNPs incorporated within the mesoporous matrix were characterized by transmission electron microscopy, energy dispersive x-ray analysis, and high-resolution scanning electron microscopy. PEI in the presence of formaldehyde enabled synthetic incorporation of AuNPs in both unmodified and modified MSNPs. The use of unmodified MSNPs was associated with an increase in the polycrystalline structure of the AuNPs within the MSNPs. The AuNPs within modified MSNPs showed better catalytic activity than those within unmodified MSNPs. MSNPs with an average size of 200 nm and with a pore size of 4–6 nm were used for synthetic insertion of AuNPs. It was found that the PEI coating enabled AuNPs synthesis within the mesopores in the presence of formaldehyde or tetrahydrofuran hydroperoxide at a temperature between 10 and 25 °C or at 60 °C in the absence of organic reducing agents. The as-made AuNP-inserted MSNPs exhibited enhanced catalytic activity. For example, these materials enabled rapid catalytic oxidation of the o-dianisidine substrate to produce a colored solution in proportion to the amount of H2O2 generated as a function of glucose oxidase-catalyzed oxidation of glucose; a linear concentration range from 80 to 800 μM and a detection limit as low as 80 μM were observed. The mesoscale pores of the as developed AuNP-inserted MSNPs were also used to entrap the hydrophobic drug paclitaxel. The results of this study indicate the potential use of the AuNP-inserted MSNPs in biocatalysis and drug delivery.}, number={1}, journal={BIOINTERPHASES}, author={Pandey, Prem C. and Pandey, Govind and Narayan, Roger J.}, year={2017}, month={Mar} }
 @article{rasic_sachan_chisholm_prater_narayan_2017, title={Room Temperature Growth of Epitaxial Titanium Nitride Films by Pulsed Laser Deposition}, volume={17}, ISSN={1528-7483 1528-7505}, url={http://dx.doi.org/10.1021/ACS.CGD.7B01278}, DOI={10.1021/acs.cgd.7b01278}, abstractNote={Reducing the thermal budget of epitaxial thin film growth has been one of the biggest challenges for the electronics industry. In this report, the room-temperature epitaxial growth of titanium nitride (TiN) thin films (∼75 nm) on (0001) Al2O3 substrates is demonstrated using a pulsed laser deposition technique. In TiN thin films, the epitaxial relationship is established by X-ray diffraction for (111)TiN//(0001) Al2O3 and TiN // Al2O3 which corresponds to a 30° rotation of titanium and nitrogen atoms with respect to the hexagon arrangement of aluminum atoms. An increase in the defect concentration is shown in the room-temperature thin film growth as compared to the ones grown at elevated temperature. A shift and broadening of the diffraction peaks is observed in the thin films as compared to the bulk value, indicating a higher residual tensile strain with decreasing growth temperature and an increase in defect concentration at room temperature. The increased defect concentration observed at...}, number={12}, journal={Crystal Growth & Design}, publisher={American Chemical Society (ACS)}, author={Rasic, Daniel and Sachan, Ritesh and Chisholm, Matthew F. and Prater, John and Narayan, Jagdish}, year={2017}, month={Oct}, pages={6634–6640} }
 @article{nguyen_narayan_2017, title={Two-photon polymerization for biological applications}, volume={20}, ISSN={["1873-4103"]}, DOI={10.1016/j.mattod.2017.06.004}, abstractNote={Two-photon polymerization (2PP) leverages the two-photon absorption (TPA) of near-infrared (NIR) radiation for additive manufacturing with sub-diffraction limit resolution within the bulk of a photosensitive material. This technology draws heavily on photosensitive polymers from the microelectronics industry, which were not optimized for TPA or for biocompatibility. 2PP with sub 100 nm resolution has been repeatedly demonstrated; however, this level of fabrication resolution comes at the expense of long fabrication times. Manufacturing of medical devices beyond surface texturing would be prohibitively slow using the current state of the art 2PP technology. Current research into TPA-sensitive photopolymers with good biocompatibility and holographic projections using spatial light modulators address current technological limitations by providing materials specifically formulated for biological applications and by making better use of available laser power for applications in which nanoscale resolution is not required.}, number={6}, journal={MATERIALS TODAY}, author={Nguyen, Alexander K. and Narayan, Roger J.}, year={2017}, pages={314–322} }
 @article{ramelan_wahyuningsih_munawaroh_narayan_2017, title={ZnO wide bandgap semiconductors preparation for optoelectronic devices}, volume={176}, ISSN={["1757-8981"]}, DOI={10.1088/1757-899x/176/1/012008}, abstractNote={ZnO nanoparticles were successfully synthesized by sol-gel method. According to unique structural and optical properties of ZnO semiconductor material, there are many potential important applications based on that material, including as an anti-reflection coating (ARC) in solar cells. Antireflective coatings (ARC) made of ZnO on top to improve the optical properties of the coating. TiO2 layer have been coated on a ZnO nanoparticle layer. ZnO nanoparticle was characterized by X-ray diffraction (XRD), Scanning electron Microscopy (SEM) and UV-Vis spectroscopy. ZnO annealed at a temperature of 600 °C have the greatest crystalinity and crystal size than that at a temperature of 400 °C and 500 °C. SEM images of ZnO shown agglomeration and grain size increases with increasing annealed temperature. While, the optical properties of ZnO increase with increasing annealed temperature. The optical transmittance spectra of the ZnO are shown that the increasing annealing temperature had effectively improved the optical transmittance of the films. While, reflectance (%R) properties shows that, the higher annealing temperature of ZnO preparations can decrease of %R value of ZnO thin layer. The difference properties of ZnO are due to differences of light scattering resulting from the crystal size effect. The ZnO prepared by annealed at 600 °C gain a good performance of the lowest reflectance value and highest size crystal. By the addition of ARC ZnO 600 °C we have been capable improve cell performance so that that cells achieve an efficiency of 0.27%.}, journal={INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS FOR BETTER FUTURE 2016}, author={Ramelan, A. H. and Wahyuningsih, S. and Munawaroh, H. and Narayan, R.}, year={2017} }
 @article{cristescu_visan_socol_surdu_oprea_grumezescu_chifiriuc_boehm_yamaleyeva_taylor_et al._2016, title={Antimicrobial activity of biopolymeric thin films containing flavonoid natural compounds and silver nanoparticles fabricated by MAPLE: A comparative study}, volume={374}, ISSN={0169-4332}, url={http://dx.doi.org/10.1016/J.APSUSC.2015.11.252}, DOI={10.1016/J.APSUSC.2015.11.252}, abstractNote={The purpose of this study was to investigate the interactions between microorganisms, including the planktonic and adherent organisms, and biopolymer (polyvinylpyrrolidone), flavonoid (quercetin dihydrate and resveratrol)-biopolymer, and silver nanoparticles-biopolymer composite thin films that were deposited using matrix assisted pulsed laser evaporation (MAPLE). A pulsed KrF* excimer laser source was used to deposit the aforementioned composite thin films, which were characterized using Fourier transform infrared spectroscopy (FT-IR), infrared microscopy (IRM), scanning electron microscopy (SEM), Grazing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM). The antimicrobial activity of thin films was quantified using an adapted disk diffusion assay against Gram-positive and Gram-negative bacteria strains. FT-IR, AFM and SEM studies confirmed that MAPLE may be used to fabricate thin films with chemical properties corresponding to the input materials as well as surface properties that are appropriate for medical use. The silver nanoparticles and flavonoid-containing films exhibited an antimicrobial activity both against Gram-positive and Gram-negative bacterial strains demonstrating the potential use of these hybrid systems for the development of novel antimicrobial strategies.}, journal={Applied Surface Science}, publisher={Elsevier BV}, author={Cristescu, R. and Visan, A. and Socol, G. and Surdu, A.V. and Oprea, A.E. and Grumezescu, A.M. and Chifiriuc, M.C. and Boehm, R.D. and Yamaleyeva, D. and Taylor, M. and et al.}, year={2016}, month={Jun}, pages={290–296} }
 @article{skoog_kumar_goering_williams_stiglich_narayan_2016, title={Biological Response of Human Bone Marrow-Derived Mesenchymal Stem Cells to Commercial Tantalum Coatings with Microscale and Nanoscale Surface Topographies}, volume={68}, ISSN={["1543-1851"]}, DOI={10.1007/s11837-016-1934-x}, number={6}, journal={JOM}, author={Skoog, Shelby A. and Kumar, Girish and Goering, Peter L. and Williams, Brian and Stiglich, Jack and Narayan, Roger J.}, year={2016}, month={Jun}, pages={1672–1678} }
 @article{skoog_kumar_zheng_sumant_goering_narayan_2016, title={Biological evaluation of ultrananocrystalline and nanocrystalline diamond coatings}, volume={27}, ISSN={["1573-4838"]}, DOI={10.1007/s10856-016-5798-y}, abstractNote={Nanostructured biomaterials have been investigated for achieving desirable tissue-material interactions in medical implants. Ultrananocrystalline diamond (UNCD) and nanocrystalline diamond (NCD) coatings are the two most studied classes of synthetic diamond coatings; these materials are grown using chemical vapor deposition and are classified based on their nanostructure, grain size, and sp 3  content. UNCD and NCD are mechanically robust, chemically inert, biocompatible, and wear resistant, making them ideal implant coatings. UNCD and NCD have been recently investigated for ophthalmic, cardiovascular, dental, and orthopaedic device applications. The aim of this study was (a) to evaluate the in vitro biocompatibility of UNCD and NCD coatings and (b) to determine if variations in surface topography and sp 3  content affect cellular response. Diamond coatings with various nanoscale topographies (grain sizes 5-400 nm) were deposited on silicon substrates using microwave plasma chemical vapor deposition. Scanning electron microscopy and atomic force microscopy revealed uniform coatings with different scales of surface topography; Raman spectroscopy confirmed the presence of carbon bonding typical of diamond coatings. Cell viability, proliferation, and morphology responses of human bone marrow-derived mesenchymal stem cells (hBMSCs) to UNCD and NCD surfaces were evaluated. The hBMSCs on UNCD and NCD coatings exhibited similar cell viability, proliferation, and morphology as those on the control material, tissue culture polystyrene. No significant differences in cellular response were observed on UNCD and NCD coatings with different nanoscale topographies. Our data shows that both UNCD and NCD coatings demonstrate in vitro biocompatibility irrespective of surface topography.}, number={12}, journal={JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE}, author={Skoog, Shelby A. and Kumar, Girish and Zheng, Jiwen and Sumant, Anirudha V. and Goering, Peter L. and Narayan, Roger J.}, year={2016}, month={Dec} }
 @article{pandey_pandey_narayan_2017, title={Controlled synthesis of polyethylenimine coated gold nanoparticles: Application in glutathione sensing and nucleotide delivery}, volume={105}, ISSN={["1552-4981"]}, DOI={10.1002/jbm.b.33647}, abstractNote={Synthesis of functional gold nanoparticles (AuNPs) justifying selectivity in biochemical interaction along with biocompatibility suited for in vivo biomedical applications has been a challenging issue. We report herein the role of polyethylenimine (PEI) in controlled synthesis of AuNPs under ambient conditions which has potentiality for sensing glutathione and selective interaction with DNA binding proteins facilitating endosomal escape for the nucleotide delivery. The choice of organic reducing agents like formaldehyde/acetaldehyde/acetyl acetone/tetrahydrofuran hydroperoxide and other similar compounds allow rapid conversion of PEI capped gold cations into AuNPs at room temperature thus controlling the functional ability of nanoparticles as a function of organic reducing agents. Both small and higher molecular weight PEI facilitates fast synthesis of AuNPs controlling cytotoxicity during in vivo biomedical applications. The AuNPs have been characterized by UV-Vis and transmission electron microscopy revealing excellent polycrystallinity and controlled nanogeometry. The cationic polymer coating enhances the electrocatalytic performances of nanoparticles. The typical biomedical application on glutathione (GSH) sensing based on peroxidase mimetic ability of as made AuNPs is studied. The as synthesized AuNPs are extreme salt and pH resistant and have potentiality for both homogeneous and heterogeneous biocatalysis. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1191-1199, 2017.}, number={5}, journal={JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS}, author={Pandey, Prem C. and Pandey, Govind and Narayan, Roger J.}, year={2017}, month={Jul}, pages={1191–1199} }
 @article{narayan_bhaumik_narayan_2016, title={Discovery of Q-phases and direct conversion of carbon into diamond and h-BN into c-BN}, volume={174}, number={3}, journal={Advanced Materials & Processes}, author={Narayan, J. and Bhaumik, A. and Narayan, R.}, year={2016}, pages={24–28} }
 @article{skoog_lu_malinauskas_sumant_zheng_goering_narayan_casey_2017, title={Effects of nanotopography on the in vitro hemocompatibility of nanocrystalline diamond coatings}, volume={105}, ISSN={["1552-4965"]}, DOI={10.1002/jbm.a.35872}, abstractNote={AbstractNanocrystalline diamond (NCD) coatings have been investigated for improved wear resistance and enhanced hemocompatibility of cardiovascular devices. The goal of this study was to evaluate the effects of NCD surface nanotopography on in vitro hemocompatibility. NCD coatings with small (NCD‐S) and large (NCD‐L) grain sizes were deposited using microwave plasma chemical vapor deposition and characterized using scanning electron microscopy, atomic force microscopy, contact angle testing, and Raman spectroscopy. NCD‐S coatings exhibited average grain sizes of 50–80 nm (RMS 5.8 nm), while NCD‐L coatings exhibited average grain sizes of 200–280 nm (RMS 23.1 nm). In vitro hemocompatibility testing using human blood included protein adsorption, hemolysis, nonactivated partial thromboplastin time, platelet adhesion, and platelet activation. Both NCD coatings demonstrated low protein adsorption, a nonhemolytic response, and minimal activation of the plasma coagulation cascade. Furthermore, the NCD coatings exhibited low thrombogenicity with minimal platelet adhesion and aggregation, and similar morphological changes to surface‐bound platelets (i.e., activation) in comparison to the HDPE negative control material. For all assays, there were no significant differences in the blood–material interactions of NCD‐S versus NCD‐L. The two tested NCD coatings, regardless of nanotopography, had similar hemocompatibility profiles compared to the negative control material (HDPE) and should be further evaluated for use in blood‐contacting medical devices. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 253–264, 2017.}, number={1}, journal={JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A}, author={Skoog, Shelby A. and Lu, Qijin and Malinauskas, Richard A. and Sumant, Anirudha V. and Zheng, Jiwen and Goering, Peter L. and Narayan, Roger J. and Casey, Brendan J.}, year={2017}, month={Jan}, pages={253–264} }
 @article{boehm_jaipan_skoog_stafslien_vanderwal_narayan_2016, title={Inkjet deposition of itraconazole onto poly(glycolic acid) microneedle arrays}, volume={11}, ISSN={["1559-4106"]}, DOI={10.1116/1.4941448}, abstractNote={Poly(glycolic acid) microneedle arrays were fabricated using a drawing lithography process; these arrays were modified with a drug release agent and an antifungal agent by piezoelectric inkjet printing. Coatings containing poly(methyl vinyl ether–co–maleic anhydride), a water-soluble drug release layer, and itraconazole (an antifungal agent), were applied to the microneedles by piezoelectric inkjet printing. Microscopic evaluation of the microneedles indicated that the modified microneedles contained the piezoelectric inkjet printing-deposited agents and that the surface coatings were released in porcine skin. Energy dispersive x-ray spectrometry aided in confirmation that the piezoelectric inkjet printing-deposited agents were successfully applied to the desired target areas of the microneedle surface. Fourier transform infrared spectroscopy was used to confirm the presence of the component materials in the piezoelectric inkjet printing-deposited material. Itraconazole-modified microneedle arrays incubated with agar plates containing Candida albicans cultures showed zones of growth inhibition.}, number={1}, journal={BIOINTERPHASES}, author={Boehm, Ryan D. and Jaipan, Panupong and Skoog, Shelby A. and Stafslien, Shane and VanderWal, Lyndsi and Narayan, Roger J.}, year={2016}, month={Mar} }
 @article{nguyen_narayan_2017, title={Liquid-Phase Laser Induced Forward Transfer for Complex Organic Inks and Tissue Engineering}, volume={45}, ISSN={0090-6964 1573-9686}, url={http://dx.doi.org/10.1007/S10439-016-1617-3}, DOI={10.1007/S10439-016-1617-3}, abstractNote={Laser induced forward transfer (LIFT) acts as a novel alternative to incumbent plotting techniques such as inkjet printing due to its ability to precisely deposit and position picoliter-sized droplets while being gentle enough to preserve sensitive structures within the ink. Materials as simple as screen printing ink to complex eukaryotic cells have been printed with applications spanning from microelectronics to tissue engineering. Biotechnology can benefit from this technique due to the efficient use of low volumes of reagent and the compatibility with a wide range of rheological properties. In addition, LIFT can be performed in a simple lab environment, not requiring vacuum or other extreme conditions. Although the basic apparatus is simple, many strategies exist to optimize the performance considering the ink and the desired pattern. The basic mechanism is similar between studies so the large number of variants can be summarized into a couple of categories and reported on with respect to their specific applications. In particular, precise and gentle deposition of complex molecules and eukaryotic cells represent the unique abilities of this technology. LIFT has demonstrated not only marked improvements in the quality of sensors and related medical devices over those manufactured with incumbent technologies but also great applicability in tissue engineering due to the high viability of printed cells.}, number={1}, journal={Annals of Biomedical Engineering}, publisher={Springer Science and Business Media LLC}, author={Nguyen, Alexander K. and Narayan, Roger J.}, year={2017}, month={Jan}, pages={84–99} }
 @article{miller_narayan_polsky_2016, title={Microneedle-based sensors for medical diagnosis}, volume={4}, ISSN={["2050-7518"]}, DOI={10.1039/c5tb02421h}, abstractNote={The field of microneedle sensors is reviewed discussing current trends and future applications.}, number={8}, journal={JOURNAL OF MATERIALS CHEMISTRY B}, author={Miller, Philip R. and Narayan, Roger J. and Polsky, Ronen}, year={2016}, pages={1379–1383} }
 @article{miller_moorman_manginell_ashlee_brener_wheeler_narayan_polsky_2016, title={Towards an Integrated Microneedle Total Analysis Chip for Protein Detection}, volume={28}, ISSN={["1521-4109"]}, DOI={10.1002/elan.201600063}, abstractNote={AbstractReal‐time monitoring of an individual’s physiologic state without constant observation by a healthcare professional necessitates the construction of an autonomous remote diagnostic device that is capable of performing a wide range of diagnostic functions. For many applications, assessing the immediate physiologic state of an individual as he or she is continuously exposed to diverse environments would require complex dynamic chemical processing scenarios that are capable of real time readouts. We seek to answer these problems by combining in vivo microneedle platforms with multifunctional lab‐on‐chip electrode arrays that are capable of detecting a wide variety of relevant biomarkers. The results presented here provide an important proof‐of‐concept demonstration of integration of microneedles with a microchip platform containing fluidic channels and electrode transducers. As shown by immunoassay detection of myoglobin and troponin, such a device may be used to extract interstitial fluid and monitor biologically important molecules.}, number={6}, journal={ELECTROANALYSIS}, author={Miller, Philip and Moorman, Matthew and Manginell, Ron and Ashlee, Carlee and Brener, Igal and Wheeler, David and Narayan, Roger and Polsky, Ronen}, year={2016}, month={Jun}, pages={1305–1310} }
 @article{zhang_wang_jin_degan_hall_boehm_jaipan_narayan_2016, title={Use of Drawing Lithography-Fabricated Polyglycolic Acid Microneedles for Transdermal Delivery of Itraconazole to a Human Basal Cell Carcinoma Model Regenerated on Mice}, volume={68}, ISSN={1047-4838 1543-1851}, url={http://dx.doi.org/10.1007/S11837-016-1841-1}, DOI={10.1007/S11837-016-1841-1}, abstractNote={Itraconazole is a triazole agent that is routinely used for treatment of nail infections and other fungal infections. Recent studies indicate that itraconazole can also inhibit the growth of basal cell carcinoma (BCC) through suppression of the Sonic Hedgehog (SHH) signaling pathway. In this study, polyglycolic acid microneedle arrays and stainless steel microneedle arrays were used for transdermal delivery of itraconazole to a human BCC model which was regenerated on mice. One-by-four arrays of 642-μm-long polyglycolic acid microneedles with sharp tips were prepared using injection molding and drawing lithography. Arrays of 85 stainless steel 800-μm-tall microneedles attached to syringes were obtained for comparison purposes. Skin grafts containing devitalized split-thickness human dermis that had been seeded with human keratinocytes transduced to express human SHH protein were sutured to the skin of immunodeficient mice. Mice with this human BCC model were treated daily for 2 weeks with itraconazole dissolved in 60% dimethylsulfoxane and 40% polyethylene glycol-400 solution; transdermal administration of the itraconazole solution was facilitated by either four 1 × 4 polyglycolic acid microneedle arrays or stainless steel microneedle arrays. The epidermal tissues treated with polyglycolic acid microneedles or stainless steel microneedles were markedly thinner than that of the control (untreated) graft tissue. These preliminary results indicate that microneedles may be used to facilitate transdermal delivery of itraconazole for localized treatment of BCC.}, number={4}, journal={JOM}, publisher={Springer Science and Business Media LLC}, author={Zhang, Jennifer and Wang, Yan and Jin, Jane Y. and Degan, Simone and Hall, Russell P. and Boehm, Ryan D. and Jaipan, Panupong and Narayan, Roger J.}, year={2016}, month={Feb}, pages={1128–1133} }
 @article{miller_boehm_skoog_edwards_rodriguez_brozik_brener_byrd_baca_ashley_et al._2015, title={Electrodeposited Iron as a Biocompatible Material for Microneedle Fabrication}, volume={27}, ISSN={["1521-4109"]}, DOI={10.1002/elan.201500199}, abstractNote={AbstractElectroplated iron was investigated as a novel material for microneedle fabrication due to its recent success as a biocompatible metal in other medical device applications. Hollow polymer microneedles were made using a laser direct write process that involved two‐photon polymerization of a commercially available Class 2a biocompatible polymer and subsequent electroplating of this structure with iron. Electroplating bath and deposition conditions were shown to affect the mechanical properties of both iron plated microneedles and iron plated on planar polymer substrates. Conditions for depositing the iron coatings were investigated in terms of grain size, residual strain, and elemental composition for planar iron samples. Fracture strength and puncture mechanics into ex vivo porcine skin for iron coated hollow microneedles were examined. Biocompatibility testing was performed using the MTT assay against human epidermal keratinocytes with several concentrations of iron extract to investigate iron as a material used for transdermal applications. Iron coatings proved to significantly improve the strength of the hollow polymer microneedles and sustained structural integrity up to 7 insertions into porcine skin without bending. A commercially available device (Medtronic MiniMed Quick‐Serter®) was used for controlled application of microneedles into porcine skin and estimations of insertion forces for the device were made. Plating conditions were optimized such that an adherent, uniform, and high purity iron coating was deposited onto polymer substrates and polymer microneedles without delamination or fracturing of the microneedles upon ex vivo insertion into porcine skin.}, number={9}, journal={ELECTROANALYSIS}, author={Miller, Philip R. and Boehm, Ryan D. and Skoog, Shelby A. and Edwards, Thayne L. and Rodriguez, Mark and Brozik, Susan and Brener, Igal and Byrd, Thomas and Baca, Justin T. and Ashley, Carlee and et al.}, year={2015}, month={Sep}, pages={2239–2249} }
 @article{cristescu_surdu_grumezescu_oprea_trusca_vasile_dorcioman_visan_socol_mihailescu_et al._2015, title={Microbial colonization of biopolymeric thin films containing natural compounds and antibiotics fabricated by MAPLE}, volume={336}, ISSN={0169-4332}, url={http://dx.doi.org/10.1016/J.APSUSC.2014.11.145}, DOI={10.1016/J.APSUSC.2014.11.145}, abstractNote={Although a great number of antibiotics are currently available, they are often rendered ineffective by the ability of microbial strains to develop genetic resistance and to grow in biofilms. Since many antimicrobial agents poorly penetrate biofilms, biofilm-associated infections often require high concentrations of antimicrobial agents for effective treatment. Among the various strategies that may be used to inhibit microbial biofilms, one strategy that has generated significant interest involves the use of bioactive surfaces that are resistant to microbial colonization. In this respect, we used matrix assisted pulsed laser evaporation (MAPLE) involving a pulsed KrF* excimer laser source (λ = 248 nm, τ = 25 ns, ν = 10 Hz) to obtain thin composite biopolymeric films containing natural (flavonoid) or synthetic (antibiotic) compounds as bioactive substances. Chemical composition and film structures were investigated by Fourier transform infrared spectroscopy and X-ray diffraction. Films morphology was studied by scanning electron microscopy and transmission electron microscopy. The antimicrobial assay of the microbial biofilms formed on these films was assessed by the viable cell counts method. The flavonoid-containing thin films showed increased resistance to microbial colonization, highlighting their potential to be used for the design of anti-biofilm surfaces.}, journal={Applied Surface Science}, publisher={Elsevier BV}, author={Cristescu, R. and Surdu, A.V. and Grumezescu, A.M. and Oprea, A.E. and Trusca, R. and Vasile, O. and Dorcioman, G. and Visan, A. and Socol, G. and Mihailescu, I.N. and et al.}, year={2015}, month={May}, pages={234–239} }
 @article{skoog_miller_boehm_sumant_polsky_narayan_2015, title={Nitrogen-incorporated ultrananocrystalline diamond microneedle arrays for electrochemical biosensing}, volume={54}, ISSN={0925-9635}, url={http://dx.doi.org/10.1016/J.DIAMOND.2014.11.016}, DOI={10.1016/J.DIAMOND.2014.11.016}, abstractNote={Microneedles are minimally invasive transdermal medical devices that are utilized for various applications, including drug delivery, fluid sampling, micro-dialysis, and electrochemical sensing. These devices are associated with less pain and tissue damage as compared with conventional hypodermic needle-based devices. In this study, we demonstrate fabrication of titanium alloy microneedle arrays with nitrogen-incorporated ultrananocrystalline diamond (N-UNCD) coatings. Microneedles were micromachined from ASTM F136 ELI Ti –6Al–4V alloy, a widely used medical-grade titanium alloy. N-UNCD coatings were deposited on the microneedles using microwave plasma enhanced chemical vapor deposition to enhance mechanical strength, increase hardness, improve biocompatibility, and provide an electrochemically stable surface. The structural and chemical properties of the N-UNCD titanium alloy microneedle arrays were evaluated using scanning electron microscopy and Raman spectroscopy. The mechanical robustness and skin penetration capability of the devices were demonstrated using cadaveric porcine skin. Finally, the electrochemical properties of the N-UNCD electrodes were evaluated; in vitro electrochemical detection of uric acid and dopamine was demonstrated using unmodified N-UNCD electrodes. These results demonstrate the application potential of N-UNCD-coated titanium alloy microneedles for transdermal electrochemical biosensing applications.}, journal={Diamond and Related Materials}, publisher={Elsevier BV}, author={Skoog, Shelby A. and Miller, Philip R. and Boehm, Ryan D. and Sumant, Anirudha V. and Polsky, Ronen and Narayan, Roger J.}, year={2015}, month={Apr}, pages={39–46} }
 @article{koroleva_deiwick_nguyen_schlie-wolter_narayan_timashev_popov_bagratashvili_chichkov_2015, title={Osteogenic Differentiation of Human Mesenchymal Stem Cells in 3-D Zr-Si Organic-Inorganic Scaffolds Produced by Two-Photon Polymerization Technique}, volume={10}, ISSN={["1932-6203"]}, DOI={10.1371/journal.pone.0118164}, abstractNote={Two-photon polymerization (2PP) is applied for the fabrication of 3-D Zr-Si scaffolds for bone tissue engineering. Zr-Si scaffolds with 150, 200, and 250 μm pore sizes are seeded with human bone marrow stem cells (hBMSCs) and human adipose tissue derived stem cells (hASCs) and cultured in osteoinductive and control media for three weeks. Osteogenic differentiation of hASCs and hBMSCs and formation of bone matrix is comparatively analyzed via alkaline phosphatase activity (ALP), calcium quantification, osteocalcin staining and scanning electron microscopy (SEM). It is observed that the 150 μm pore size Zr-Si scaffolds support the strongest matrix mineralization, as confirmed by calcium deposition. Analysis of ALP activity, osteocalcin staining and SEM observations of matrix mineralization reveal that mesenchymal stem cells cultured on 3-D scaffolds without osteogenic stimulation spontaneously differentiate towards osteogenic lineage. Nanoindentation measurements show that aging of the 2PP-produced Zr-Si scaffolds in aqueous or alcohol media results in an increase in the scaffold Young’s modulus and hardness. Moreover, accelerated formation of bone matrix by hASCs is noted, when cultured on the scaffolds with lower Young’s moduli and hardness values (non aged scaffolds) compared to the cells cultured on scaffolds with higher Young’s modulus and hardness values (aged scaffolds). Presented results support the potential application of Zr-Si scaffolds for autologous bone tissue engineering.}, number={2}, journal={PLOS ONE}, author={Koroleva, Anastasia and Deiwick, Andrea and Nguyen, Alexander and Schlie-Wolter, Sabrina and Narayan, Roger and Timashev, Peter and Popov, Vladimir and Bagratashvili, Viktor and Chichkov, Boris}, year={2015}, month={Feb} }
 @article{boehm_daniels_stafslien_nasir_lefebvre_narayan_2015, title={Polyglycolic acid microneedles modified with inkjet-deposited antifungal coatings}, volume={10}, ISSN={["1559-4106"]}, DOI={10.1116/1.4913378}, abstractNote={In this study, the authors examined use of piezoelectric inkjet printing to apply an antifungal agent, voriconazole, to the surfaces of biodegradable polyglycolic acid microneedles. Polyglycolic acid microneedles with sharp tips (average tip radius = 25 ± 3 μm) were prepared using a combination of injection molding and drawing lithography. The elastic modulus (9.9 ± 0.3 GPa) and hardness (588.2 ± 33.8 MPa) values of the polyglycolic acid material were determined using nanoindentation and were found to be suitable for use in transdermal drug delivery devices. Voriconazole was deposited onto the polyglycolic acid microneedles by means of piezoelectric inkjet printing. It should be noted that voriconazole has poor solubility in water; however, it is readily soluble in many organic solvents. Optical imaging, scanning electron microscopy, energy dispersive x-ray spectrometry, and Fourier transform infrared spectroscopy were utilized to examine the microneedle geometries and inkjet-deposited surface coatings. Furthermore, an in vitro agar plating study was performed on the unmodified, vehicle-modified, and voriconazole-modified microneedles. Unlike the unmodified and vehicle-modified microneedles, the voriconazole-modified microneedles showed antifungal activity against Candida albicans. The unmodified, vehicle-modified, and voriconazole-modified microneedles did not show activity against Escherichia coli, Pseudomonas aeruginosa, or Staphylococcus aureus. The results indicate that piezoelectric inkjet printing may be useful for loading transdermal drug delivery devices such as polyglycolic acid microneedles with antifungal pharmacologic agents and other pharmacologic agents with poor solubility in aqueous solutions.}, number={1}, journal={BIOINTERPHASES}, author={Boehm, Ryan D. and Daniels, Justin and Stafslien, Shane and Nasir, Adnan and Lefebvre, Joe and Narayan, Roger J.}, year={2015}, month={Mar} }
 @article{pappa_caballero_dennis_skancke_narayan_dahl_aalst_2014, title={Biochemical Properties of Tissue-Engineered Cartilage}, volume={25}, ISSN={["1536-3732"]}, DOI={10.1097/scs.0b013e3182a2eb56}, abstractNote={ObjectiveMicrotia is treated with rib cartilage sculpting and staged procedures; though aesthetically pleasing, these constructs lack native ear flexibility. Tissue-engineered (TE) elastic cartilage may bridge this gap; however, TE cartilage implants lead to hypertrophic changes with calcification and loss of flexibility. Retaining flexibility in TE cartilage must focus on increased elastin, maintained collagen II, decreased collagen X, with prevention of calcification. This study compares biochemical properties of human cartilage to TE cartilage from umbilical cord mesenchymal stem cells (UCMSCs). Our goal is to establish a baseline for clinically useful TE cartilage. MethodsDiscarded cartilage from conchal bowl, microtic ears, preauricular tags, rib, and TE cartilage were evaluated for collagen I, II, X, calcium, glycosaminoglycans, elastin, and fibrillin I and III. Human UCMSCs were chondroinduced on 2D surfaces and 3D D,L-lactide-co-glycolic acid (PLGA) fibers. ResultsCartilage samples demonstrated similar staining for collagens I, II, and X, elastin, and fibrillin I and III, but differed from rib. TE pellets and PLGA-supported cartilage were similar to auricular samples in elastin and fibrillin I staining. TE samples were exclusively stained for fibrillin III. Only microtic samples demonstrated calcium staining. ConclusionsTE cartilage expressed similar levels of elastin, fibrillin I, and collagens I and X when compared to native cartilage. Microtic cartilage demonstrated elevated calcium, suggesting this abnormal tissue may not be a viable cell source for TE cartilage. TE cartilage appears to recapitulate the embryonic development of fibrillin III, which is not expressed in adult tissue, possibly providing a strategy to control TE elastic cartilage phenotype.}, number={1}, journal={JOURNAL OF CRANIOFACIAL SURGERY}, author={Pappa, Andrew K. and Caballero, Montserrat and Dennis, Robert G. and Skancke, Matthew D. and Narayan, Roger J. and Dahl, John P. and Aalst, John A.}, year={2014}, month={Jan}, pages={111–115} }
 @article{narayan_2014, title={Biological, Electronic, and Functional Thin Films}, volume={66}, ISSN={["1543-1851"]}, DOI={10.1007/s11837-014-0936-9}, abstractNote={Processing of thin films has a long and extensive history; techniques such as electroplating, sputtering, and thermal evaporation date to the nineteenth century. As noted by Van Hove, the large and growing field of nanoscience evolved from the field of surface science over the past half century. In recent years, thin film development for nanoelectronic devices, optoelectronic devices, thermoelectric devices, batteries, sensors, wearable devices, implantable devices, and water purification membranes has generated significant interest. New technologies, including roll-to-roll processing, are being developed that will enable thin film processing at lower cost than conventional methods. In this special topic, efforts by several leading researchers to develop thin films for biological, electronic, and functional thin films are considered. For example, in their article ‘‘Processing for Highly Emissive CZ-Silicon by Depositing Stressed Sol–Gel Films,’’ S. Abedrabbo, A.T. Fiory, and N.M. Ravindra discuss the use of an inexpensive sol–gel approach to create erbium-doped silicon oxide coatings for optical applications. El Mostafa Benchafia, Chi Yu, Marek Sosnowski, N.M. Ravindra, and Zafar Iqbal, in their paper titled ‘‘Plasma Synthesis of Nitrogen Clusters on Carbon Nanotube Sheets,’’ used a radio-frequency plasma synthesis approach based on plasma-enhanced chemical vapor deposition for growth of polymeric nitrogen clusters on carbon nanotube sheets and nanopaper. The paper titled ‘‘Electrical Resistance Decrease Due to Grain Coarsening under Cyclic Deformation’’ by O. Glushko and M.J. Cordill examines electron beam-evaporated copper films on polyimide substrates under cyclic tensile loading and associated a reduction in electrical resistance in these materials with room-temperature, strain-induced grain coarsening. Robert A. Hall, Steven M. George, Yeongae Kim, Woonbong Hwang, Meghan E. Samberg, Nancy A. Monteiro-Riviere, and Roger J. Narayan, in their paper titled ‘‘Growth of Zircone on Nanoporous Alumina Using Molecular Layer Deposition,’’ examine the growth of skin cells on nanoporous alumina that was coated with a zirconiumcontaining hybrid organic/inorganic polymer. Sarang V. Muley and Nuggehalli M. Ravindra review in their paper ‘‘Emissivity of Electronic Materials, Coatings, and Structures’’ the optical properties of several types of single-component and multilayered materials. A.M. Oladoye, J.G. Carton, and A.G. Olabi describe the use of a modified micro-blasting process known as CoBlast for depositing graphite-containing coatings on stainless steel and titanium substrates in their paper ‘‘Characterization of Graphite Coatings Produced by CoBlast Technology.’’ These coatings have potential corrosion and tribological applications. The paper titled ‘‘Graphene: The Thinnest Known Coating for Corrosion Protection’’ by R.K. Singh and Abhishek Tiwari considers the use of graphene as a corrosionresistant coating for metals and metal alloys, while James Winnett and Kajal K. Mallick discuss the use of an adaptive foam reticulation approach to create porous scaffolds out of titanium and titanium-6% aluminum-4% vanadium alloy in their paper titled ‘‘Parametric Characterization of Porous 3D Bioscaffolds Fabricated by an Adaptive Foam Reticulation Technique.’’ We would like to thank Shirley Litzinger and Maureen Byko for their tireless efforts to make the ‘‘Biological, Electronic, and Functional Thin Films’’ special topic possible. We hope that this topic contributes to an improved understanding of thin film science and signifies the major role of The Minerals, Metals & Materials Society in dissemination of information on thin films and other functional materials.}, number={4}, journal={JOM}, author={Narayan, Roger}, year={2014}, month={Apr}, pages={588–589} }
 @article{petrochenko_zhang_bayati_skoog_phillips_kumar_narayan_goering_2014, title={Cytotoxic evaluation of nanostructured zinc oxide (ZnO) thin films and leachates}, volume={28}, ISSN={["0887-2333"]}, DOI={10.1016/j.tiv.2014.05.004}, abstractNote={Nanostructured ZnO films have potential use as coatings on medical devices and food packaging due to their antimicrobial and UV-protection properties. However, their influence on mammalian cells during clinical use is not fully understood. This study investigated the potential cytotoxicity of ZnO thin films in RAW 264.7 macrophages. ZnO thin films (∼96 nm thick with a 50 nm grain) were deposited onto silicon wafers using pulsed laser deposition. Cells grown directly on ZnO thin film coatings exhibited less toxicity than cells exposed to extracts of the coatings. Cells on ZnO thin films exhibited a 43% and 68% decrease in cell viability using the MTT and 7-AAD/Annexin V flow cytometry assays, respectively, after a 24-h exposure as compared to controls. Undiluted 100% 24- and 48-h extracts decreased viability by 89%, increased cell death by LDH release to 76% 24 h after treatment, and increased ROS after 5–24 h of exposure. In contrast, no cytotoxicity or ROS were observed for 25% and 50% extracts, indicating a tolerable concentration. Roughly 24 and 34 μg/m2 Zn leached off the surfaces after 24 and 48 h of incubation, respectively. ZnO coatings may produce gradual ion release which becomes toxic after a certain level and should be evaluated using both direct exposure and extraction methods.}, number={6}, journal={TOXICOLOGY IN VITRO}, author={Petrochenko, Peter E. and Zhang, Qin and Bayati, Reza and Skoog, Shelby A. and Phillips, K. Scott and Kumar, Girish and Narayan, Roger J. and Goering, Peter L.}, year={2014}, month={Sep}, pages={1144–1152} }
 @article{miller_xiao_brener_burckel_narayan_polsky_2014, title={Diagnostic Devices: Microneedle-Based Transdermal Sensor for On-Chip Potentiometric Determination of K+(Adv. Healthcare Mater. 6/2014)}, volume={3}, ISSN={2192-2640}, url={http://dx.doi.org/10.1002/ADHM.201470032}, DOI={10.1002/ADHM.201470032}, abstractNote={A transdermal sensing platform for detection of electrolytes is developed by P. R. Miller, R. Narayan, R. Polsky and colleagues. On page 876, hollow polymer microneedles are integrated with a microfluidic chip for detecting potassium using a solid state ion selective electrode transducer. The device could one day be used as an on body point-of-care medical diagnostic device.}, number={6}, journal={Advanced Healthcare Materials}, publisher={Wiley}, author={Miller, Philip R. and Xiao, Xiaoyin and Brener, Igal and Burckel, D. Bruce and Narayan, Roger and Polsky, Ronen}, year={2014}, month={Jun}, pages={948–948} }
 @article{hall_george_kim_hwang_samberg_monteiro-riviere_narayan_2014, title={Growth of Zircone on Nanoporous Alumina Using Molecular Layer Deposition}, volume={66}, ISSN={["1543-1851"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84898791280&partnerID=MN8TOARS}, DOI={10.1007/s11837-014-0933-z}, number={4}, journal={JOM}, author={Hall, Robert A. and George, Steven M. and Kim, Yeongae and Hwang, Woonbong and Samberg, Meghan E. and Monteiro-Riviere, Nancy A. and Narayan, Roger J.}, year={2014}, month={Apr}, pages={649–653} }
 @article{boehm_miller_daniels_stafslien_narayan_2014, title={Inkjet printing for pharmaceutical applications}, volume={17}, ISSN={["1873-4103"]}, DOI={10.1016/j.mattod.2014.04.027}, abstractNote={Miconazole is an imidazole used for treatment of fungal infections that exhibits poor solubility in polar solvents (e.g., aqueous solutions). Microneedles, small-scale lancet-shaped devices that are commonly used for delivery of pharmacologic agents and vaccines, were made out of an acid anhydride copolymer using visible light dynamic mask micro-stereolithography/micromolding and loaded with miconazole using a piezoelectric inkjet printer. The miconazole-coated microneedles showed biodegradation and antifungal activity against the organism Candida albicans (ATCC 90028) on Sabouraud dextrose agar using an in vitro agar plating method. The results of this study demonstrate that piezoelectric inkjet printing may be used load microneedles and other drug delivery devices with pharmacologic agents. Miconazole-loaded microneedles prepared by the visible light dynamic mask micro-stereolithography–micromolding–piezoelectric inkjet printing approach have potential use in transdermal treatment of cutaneous fungal infections.}, number={5}, journal={MATERIALS TODAY}, author={Boehm, Ryan D. and Miller, Philip R. and Daniels, Justin and Stafslien, Shane and Narayan, Roger J.}, year={2014}, month={Jun}, pages={247–252} }
 @article{petrochenko_torgersen_gruber_hicks_zheng_kumar_narayan_goering_liska_stampfl_et al._2015, title={Laser 3D Printing with Sub-Microscale Resolution of Porous Elastomeric Scaffolds for Supporting Human Bone Stem Cells}, volume={4}, ISSN={2192-2640}, url={http://dx.doi.org/10.1002/ADHM.201400442}, DOI={10.1002/ADHM.201400442}, abstractNote={A reproducible method is needed to fabricate 3D scaffold constructs that results in periodic and uniform structures with precise control at sub‐micrometer and micrometer length scales. In this study, fabrication of scaffolds by two‐photon polymerization (2PP) of a biodegradable urethane and acrylate‐based photoelastomer is demonstrated. This material supports 2PP processing with sub‐micrometer spatial resolution. The high photoreactivity of the biophotoelastomer permits 2PP processing at a scanning speed of 1000 mm s−1, facilitating rapid fabrication of relatively large structures (>5 mm3). These structures are custom printed for in vitro assay screening in 96‐well plates and are sufficiently flexible to enable facile handling and transplantation. These results indicate that stable scaffolds with porosities of greater than 60% can be produced using 2PP. Human bone marrow stromal cells grown on 3D scaffolds exhibit increased growth and proliferation compared to smooth 2D scaffold controls. 3D scaffolds adsorb larger amounts of protein than smooth 2D scaffolds due to their larger surface area; the scaffolds also allow cells to attach in multiple planes and to completely infiltrate the porous scaffolds. The flexible photoelastomer material is biocompatible in vitro and is associated with facile handling, making it a viable candidate for further study of complex 3D‐printed scaffolds.}, number={5}, journal={Advanced Healthcare Materials}, publisher={Wiley}, author={Petrochenko, Peter E. and Torgersen, Jan and Gruber, Peter and Hicks, Lucas A. and Zheng, Jiwen and Kumar, Girish and Narayan, Roger J. and Goering, Peter L. and Liska, Robert and Stampfl, Jürgen and et al.}, year={2015}, month={Apr}, pages={739–747} }
 @article{bueno_el-sharif_salles_boehm_narayan_paixão_reddy_2014, title={MIP-based electrochemical protein profiling}, volume={204}, ISSN={0925-4005}, url={http://dx.doi.org/10.1016/J.SNB.2014.07.100}, DOI={10.1016/J.SNB.2014.07.100}, abstractNote={We present the development of an electrochemical biosensor based on modified glassy carbon (GC) electrodes using hydrogel-based molecularly imprinted polymers (MIPs) has been fabricated for protein detection. The coupling of pattern recognition techniques via principal component analysis (PCA) has resulted in unique protein fingerprints for corresponding protein templates, allowing for MIP-based protein profiling. Polyacrylamide MIPs for memory imprinting of bovine haemoglobin (BHb), equine myoglobin (EMb), cytochrome C (Cyt C), and bovine serum albumin (BSA), alongside a non-imprinted polymer (NIP) control, were spectrophotometrically, and electrochemically characterised using modified GC electrodes. Rebinding capacities (Q) were revealed to be higher for larger proteins (BHb and BSA, Q ≈ 4.5) while (EMb and Cyt C, Q ≈ 2.5). Electrochemical results show that due to the selective nature of MIPs, protein arrival at the electrode via diffusion is delayed, in comparison to a NIP, by attractive selective interactions with exposed MIP cavities. However, at lower concentrations such discriminations are difficult due to low levels of MIP rebinding. PCA loading plots revealed 5 variables responsible for the separation of the proteins; Ep, Ip, E1/2, Iat −0.8 V, ΔIdecay peak current to −0.8 V. Statistical symmetric measures of agreement using Cohen's kappa coefficient (κ) were revealed to be 63% for bare GC, 96% for NIP and 100% for MIP. Therefore, our results show that with the use of PCA such discriminations are achievable, also with the advantage of faster detection rates. The possibilities for this MIP technology once fully developed are vast, including uses in bio-sample clean-up or selective extraction, replacement of biological antibodies in immunoassays, as well as biosensors for medicine, food and the environment.}, journal={Sensors and Actuators B: Chemical}, publisher={Elsevier BV}, author={Bueno, Lígia and El-Sharif, Hazim F. and Salles, Maiara O. and Boehm, Ryan D. and Narayan, Roger J. and Paixão, Thiago R.L.C. and Reddy, Subrayal M.}, year={2014}, month={Dec}, pages={88–95} }
 @article{valdés-ramírez_li_kim_jia_bandodkar_nuñez-flores_miller_wu_narayan_windmiller_et al._2014, title={Microneedle-based self-powered glucose sensor}, volume={47}, ISSN={1388-2481}, url={http://dx.doi.org/10.1016/j.elecom.2014.07.014}, DOI={10.1016/j.elecom.2014.07.014}, abstractNote={A microneedle-based self-powered biofuel-cell glucose sensor is described. The biofuel cell sensor makes use of the integration of modified carbon pastes into hollow microneedle devices. The system displays defined dependence of the power density vs glucose concentration in artificial interstitialfluid. An excellent selectivity against common electroactive interferences and long-term stability are obtained. The attractive performance of the device indicates considerable promise for subdermal glucose monitoring.}, journal={Electrochemistry Communications}, publisher={Elsevier BV}, author={Valdés-Ramírez, Gabriela and Li, Ya-Chieh and Kim, Jayoung and Jia, Wenzhao and Bandodkar, Amay J. and Nuñez-Flores, Rogelio and Miller, Philip R. and Wu, Shu-Yii and Narayan, Roger and Windmiller, Joshua R. and et al.}, year={2014}, month={Oct}, pages={58–62} }
 @article{punugupati_narayan_hunte_2014, title={Strain induced ferromagnetism in epitaxial Cr2O3 thin films integrated on Si(001)}, volume={105}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.4896975}, DOI={10.1063/1.4896975}, abstractNote={We report on the epitaxial growth and magnetic properties of antiferromagnetic and magnetoelectric (ME) Cr2O3 thin films deposited on cubic yttria stabilized zirconia (c-YSZ)/Si(001) using pulsed laser deposition. The X-ray diffraction (2ϴ and Φ) and TEM characterizations confirm that the films were grown epitaxially. The Cr2O3(0001) growth on YSZ(001) occurs with twin domains. There are four domains of Cr2O3 with in-plane rotation of 30° or 150° from each other about the [0001] growth direction. The epitaxial relation between the layers is given as [001]Si ‖ [001]YSZ ‖ [0001]Cr2O3 and [100]Si ǁ [100]YSZ ǁ [101¯0] Cr2O3 or [112¯0] Cr2O3. Though the bulk Cr2O3 is an antiferromagnetic with TN = 307 K, we found that the films exhibit ferromagnetic like hysteresis loops with high saturation and finite coercive field up to 400 K. The thickness dependent magnetizations together with oxygen annealing results suggest that the ferromagnetism (FM) is due to oxygen related defects whose concentration is controlled by strain present in the films. This FM, in addition to the intrinsic magneto-electric properties of Cr2O3, opens the door to relevant spintronics applications.}, number={13}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Punugupati, Sandhyarani and Narayan, Jagdish and Hunte, Frank}, year={2014}, month={Sep}, pages={132401} }
 @misc{narayan_2014, title={Transdermal Delivery of Insulin via Microneedles}, volume={10}, ISSN={["1550-7041"]}, DOI={10.1166/jbn.2014.1976}, abstractNote={Treatment of insulin-dependent diabetes mellitus, also known as Type 1 diabetes mellitus, requires delivery of exogenous insulin via injection or pump. An alternative to syringe-based subcutaneous delivery of insulin involves use of microneedles. These < 300 μm diameter, 50-900 μm long needle shaped devices may be used for intradermal delivery of insulin. Benefits associated with microneedle-based delivery of insulin include minimal training for use, painless insertion, as well as the potential to combine microneedles with sensors and drug delivery devices to create an autonomous artificial pancreas. In this review, the efforts of academic and industrial researchers over the past decade to examine the functionality of microneedles for delivery of insulin, including insulin-containing nanomaterials, via in vitro, ex vivo, and in vivo studies are considered.}, number={9}, journal={JOURNAL OF BIOMEDICAL NANOTECHNOLOGY}, author={Narayan, Roger J.}, year={2014}, month={Sep}, pages={2244–2260} }
 @article{skoog_nguyen_kumar_zheng_goering_koroleva_chichkov_narayan_2014, title={Two-photon polymerization of 3-D zirconium oxide hybrid scaffolds for long-term stem cell growth}, volume={9}, ISSN={["1559-4106"]}, DOI={10.1116/1.4873688}, abstractNote={Two-photon polymerization is a technique that involves simultaneous absorption of two photons from a femtosecond laser for selective polymerization of a photosensitive material. In this study, two-photon polymerization was used for layer-by-layer fabrication of 3-D scaffolds composed of an inorganic–organic zirconium oxide hybrid material. Four types of scaffold microarchitectures were created, which exhibit layers of parallel line features at various orientations as well as pores between the line features. Long-term cell culture studies involving human bone marrow stromal cells were conducted using these 3-D scaffolds. Cellular adhesion and proliferation were demonstrated on all of the scaffold types; tissuelike structure was shown to span the pores. This study indicates that two-photon polymerization may be used to create microstructured scaffolds out of an inorganic–organic zirconium oxide hybrid material for use in 3-D tissue culture systems.}, number={2}, journal={BIOINTERPHASES}, author={Skoog, Shelby A. and Nguyen, Alexander K. and Kumar, Girish and Zheng, Jiwen and Goering, Peter L. and Koroleva, Anastasia and Chichkov, Boris N. and Narayan, Roger J.}, year={2014}, month={Jun} }
 @article{cristescu_popescu_dorcioman_miroiu_socol_mihailescu_gittard_miller_narayan_enculescu_et al._2013, title={Antimicrobial activity of biopolymer-antibiotic thin films fabricated by advanced pulsed laser methods}, volume={278}, ISSN={["0169-4332"]}, DOI={10.1016/j.apsusc.2013.01.062}, abstractNote={Abstract We report on thin film deposition by matrix assisted pulsed laser evaporation (MAPLE) of two polymer–drug composite thin film systems. A pulsed KrF* excimer laser source ( λ  = 248 nm, τ  = 25 ns, ν  = 10 Hz) was used to deposit composite thin films of poly( d , l -lactide) (PDLLA) containing several gentamicin concentrations. FTIR spectroscopy was used to demonstrate that MAPLE-transferred materials exhibited chemical structures similar to those of drop cast materials. Scanning electron microscopy data indicated that MAPLE may be used to fabricate thin films of good morphological quality. The activity of PDLLA–gentamicin composite thin films against Staphylococcus aureus bacteria was demonstrated using drop testing. The influence of drug concentration on microbial viability was also assessed. Our studies indicate that polymer–drug composite thin films prepared by MAPLE may be used to impart antimicrobial activity to implants, medical devices, and other contact surfaces.}, journal={APPLIED SURFACE SCIENCE}, author={Cristescu, R. and Popescu, C. and Dorcioman, G. and Miroiu, F. M. and Socol, G. and Mihailescu, I. N. and Gittard, S. D. and Miller, P. R. and Narayan, R. J. and Enculescu, M. and et al.}, year={2013}, month={Aug}, pages={211–213} }
 @article{narayan_2013, title={Big possibilities for small scale implants}, volume={16}, ISSN={["1369-7021"]}, DOI={10.1016/j.mattod.2013.06.007}, number={6}, journal={MATERIALS TODAY}, author={Narayan, Roger J.}, year={2013}, month={Jun}, pages={204–205} }
 @article{bayati_molaei_wu_budai_liu_narayan_narayan_2013, title={Correlation between structure and semiconductor-to-metal transition characteristics of VO2/TiO2/sapphire thin film heterostructures}, volume={61}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2013.09.019}, abstractNote={This study focuses on the role of strain and thin film epitaxy on the semiconductor-to-metal transition (SMT) characteristics of single crystalline VO2 thin films. The VO2/TiO2 heterostructures of controlled orientations were epitaxially grown on m-cut, r-cut and c-cut sapphire substrates. Detailed structural investigations were performed using high-resolution X-ray diffraction (2θ–θ and φ scans) and high-resolution transmission electron microscopy techniques to correlate SMT properties with microstructural characteristics. Monoclinic (M1) VO2 thin films with (1 0 0), (0 0 1) and (2¯01) out-of-plane orientations were grown on TiO2(1 0 1)/r-sapphire, TiO2(1 0 0)/c-sapphire and TiO2(0 0 1)/m-sapphire platforms, respectively. The in-plane alignments across the interfaces were established to be [0 1 0](1 0 0)VO2||[0 1 0](1 0 1)TiO2, [1 0 0](0 0 1)VO2||[0 0 1](1 0 0)TiO2 and [010](2¯01)VO2‖[010](001)TiO2 for r-sapphire, c-sapphire and m-sapphire substrates, respectively. We were able to tune the SMT temperature of VO2 epilayers from ∼313 K to 354 K (bulk Tc ≈ 340 K). The SMT characteristics were interpreted based upon the residual strain in the VO2 lattice, particularly along the c-axis of tetragonal VO2. This research introduces the VO2-based single crystalline heterostructures as a potential candidate for a wide range of applications where different transition temperatures are required.}, number={20}, journal={ACTA MATERIALIA}, author={Bayati, M. R. and Molaei, R. and Wu, F. and Budai, J. D. and Liu, Y. and Narayan, R. J. and Narayan, J.}, year={2013}, month={Dec}, pages={7805–7815} }
 @article{divan_makarova_skoog_narayan_sumant_tang_moldovan_2014, title={High-aspect-ratio nanoporous membranes made by reactive ion etching and e-beam and interference lithography}, volume={20}, ISSN={["1432-1858"]}, DOI={10.1007/s00542-013-1932-7}, number={10-11}, journal={MICROSYSTEM TECHNOLOGIES-MICRO-AND NANOSYSTEMS-INFORMATION STORAGE AND PROCESSING SYSTEMS}, author={Divan, Ralu and Makarova, Olga V. and Skoog, Shelby and Narayan, Roger and Sumant, Anirudha V. and Tang, Cha-Mei and Moldovan, Nicolaie}, year={2014}, month={Oct}, pages={1797–1802} }
 @article{boehm_miller_schell_perfect_narayan_2013, title={Inkjet Printing of Amphotericin B onto Biodegradable Microneedles Using Piezoelectric Inkjet Printing}, volume={65}, ISSN={["1543-1851"]}, DOI={10.1007/s11837-013-0574-7}, number={4}, journal={JOM}, author={Boehm, Ryan D. and Miller, Philip R. and Schell, Wiley A. and Perfect, John R. and Narayan, Roger J.}, year={2013}, month={Apr}, pages={525–533} }
 @article{bayati_joshi_narayan_narayan_2013, title={Low-temperature processing and control of structure and properties of TiO2/c-sapphire epitaxial heterostructures}, volume={28}, ISSN={["2044-5326"]}, DOI={10.1557/jmr.2013.42}, abstractNote={Abstract}, number={13}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Bayati, Mohammad Reza and Joshi, Shivani and Narayan, Roger Jay and Narayan, Jay}, year={2013}, month={Jul}, pages={1669–1679} }
 @article{miller_xiao_brener_burckel_narayan_polsky_2014, title={Microneedle-Based Transdermal Sensor for On-Chip Potentiometric Determination of K+}, volume={3}, ISSN={["2192-2659"]}, DOI={10.1002/adhm.201300541}, abstractNote={The determination of electrolytes is invaluable for point of care diagnostic applications. An ion selective transdermal microneedle sensor is demonstrated for potassium by integrating a hollow microneedle with a microfluidic chip to extract fluid through a channel towards a downstream solid‐state ion‐selective‐electrode (ISE). 3D porous carbon and 3D porous graphene electrodes, made via interference lithography, are compared as solid‐state transducers for ISE's and evaluated for electrochemical performance, stability, and selectivity. The porous carbon K+ ISE's show better performance than the porous graphene K+ ISE's, capable of measuring potassium across normal physiological concentrations in the presence of interfering ions with greater stability. This new microfluidic/microneedle platform shows promise for medical applications.}, number={6}, journal={ADVANCED HEALTHCARE MATERIALS}, author={Miller, Philip R. and Xiao, Xiaoyin and Brener, Igal and Burckel, D. Bruce and Narayan, Roger and Polsky, Ronen}, year={2014}, month={Jun}, pages={876–881} }
 @article{petrochenko_scarel_hyde_parsons_skoog_zhang_goering_narayan_2013, title={Prevention of Ultraviolet (UV)-Induced Surface Damage and Cytotoxicity of Polyethersulfone Using Atomic Layer Deposition (ALD) Titanium Dioxide}, volume={65}, ISSN={1047-4838 1543-1851}, url={http://dx.doi.org/10.1007/S11837-013-0565-8}, DOI={10.1007/S11837-013-0565-8}, abstractNote={Nanostructured surfaces are finding use in several medical applications, including tissue scaffolds and wound dressings. These surfaces are frequently manufactured from biocompatible polymers that are susceptible to ultraviolet (UV) damage. Polyethersulfone (PES) is a biocompatible polymer that undergoes oxidation and degradation when exposed to ultraviolet (UV) light. A uniform TiO2 coating can protect PES during exposure to UV sources (e.g., germicidal lamps and sunlight). The goal of this study was to determine whether atomic layer deposition (ALD) can successfully be used to grow TiO2 onto PES, protect it from UV irradiation, and reduce macrophage in vitro cytotoxicity. TiO2 was ALD-coated onto PES at 21 nm thickness. Uncoated PES exposed to UV for 30 min visibly changed color, whereas TiO2-coated PES showed no color change, indicating limited degradation. Macrophages exposed to UV-treated PES for 48 h showed reduced cell viability (via MTT assay) to 18% of control. In contrast, the cell viability for UV-treated TiO2-coated PES was 90% of control. Non-UV treated PES showed no decrease in cell viability. The results indicate that ALD of TiO2 thin films is a useful technique to protect polymers from UV damage and to retain low cytotoxicity to macrophages and other types of cells that are involved in wound healing. TiO2- coated PES membranes also have potential use in direct methanol fuel cells and in wastewater treatment membranes.}, number={4}, journal={JOM}, publisher={Springer Science and Business Media LLC}, author={Petrochenko, Peter E. and Scarel, Giovanna and Hyde, G. Kevin and Parsons, Gregory N. and Skoog, Shelby A. and Zhang, Qin and Goering, Peter L. and Narayan, Roger J.}, year={2013}, month={Feb}, pages={550–556} }
 @article{narayan_2013, title={Recent Developments in Functional Thin Films}, volume={65}, ISSN={["1047-4838"]}, DOI={10.1007/s11837-013-0577-4}, number={4}, journal={JOM}, author={Narayan, Roger J.}, year={2013}, month={Apr}, pages={517–518} }
 @article{bayati_molaei_budai_narayan_narayan_2013, title={Role of substrate crystallographic characteristics on structure and properties of rutile TiO2 epilayers}, volume={114}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.4816470}, DOI={10.1063/1.4816470}, abstractNote={To investigate heterostructures of interest for catalytic applications, we integrated rutile TiO2 epitaxial thin films with Al2O3(0001), Al2O3(101¯0), and Al2O3(011¯2) substrates and studied structure and properties of the epilayers as a function of the crystallographic characteristics of the substrate. The epitaxial relationship across the film/substrate interfaces was established as (100)rutile‖(0001)c-sapphire and [001]rutile‖[101¯0]c-sapphire, (001)rutile‖[101¯0)m-sapphire, and [100]rutile‖[0001]m-sapphire, (101)rutile‖(011¯2)r-sapphire and [010]rutile‖(011¯2)r-sapphire. The origin and the relaxation mechanism of stress and strain for each heterostructure were studied in detail. It was revealed that large lattice misfit strains relax easily even if the primary slip system is not active due to the epitaxial alignment between the film and substrate and orientation of the in-plane stresses. We also showed that even small misfit strains can relax provided that the primary slip system is active. The origin of the residual strains in the epilayers was found to be primarily due to thermal misfit and defect/impurity strains. In addition, the decomposition rate of 4-chlorophenol by the rutile/sapphire heterostructures under ultraviolet illumination was measured. The (001)-plane was found to be the most photoactive face of rutile TiO2, while the (100)-plane showed the lowest photocatalytic activity. The difference in the photochemical characteristics was attributed to the atomic arrangement on different crystallographic surface planes.}, number={4}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Bayati, M. R. and Molaei, R. and Budai, J. D. and Narayan, R. J. and Narayan, J.}, year={2013}, month={Jul}, pages={044314} }
 @article{xiao_miller_narayan_brozik_wheeler_brener_wang_burckel_polsky_2014, title={Simultaneous Detection of Dopamine, Ascorbic Acid and Uric Acid at Lithographically-Defined 3D Graphene Electrodes}, volume={26}, ISSN={["1521-4109"]}, DOI={10.1002/elan.201300253}, abstractNote={AbstractThree dimensional graphene electrodes are presented as highly sensitive electrochemical transducers for the detection of dopamine, ascorbic acid, and uric acid. The detection limits for each separate analyte is approximately 5 µM. In addition the oxidative peak potentials for each are sufficiently separated such that the simultaneous detection of a mixture can be accomplished without any modification steps leading to three well resolved peaks. Increased steady state mass transport profiles due to enhanced diffusion effects at the open porous three dimensional graphene electrodes are also observed.}, number={1}, journal={ELECTROANALYSIS}, author={Xiao, Xiaoyin and Miller, Philip R. and Narayan, Roger J. and Brozik, Susan M. and Wheeler, David R. and Brener, Igal and Wang, Joseph and Burckel, D. Bruce and Polsky, Ronen}, year={2014}, month={Jan}, pages={52–56} }
 @article{skoog_goering_narayan_2014, title={Stereolithography in tissue engineering}, volume={25}, ISSN={["1573-4838"]}, DOI={10.1007/s10856-013-5107-y}, abstractNote={Several recent research efforts have focused on use of computer-aided additive fabrication technologies, commonly referred to as additive manufacturing, rapid prototyping, solid freeform fabrication, or three-dimensional printing technologies, to create structures for tissue engineering. For example, scaffolds for tissue engineering may be processed using rapid prototyping technologies, which serve as matrices for cell ingrowth, vascularization, as well as transport of nutrients and waste. Stereolithography is a photopolymerization-based rapid prototyping technology that involves computer-driven and spatially controlled irradiation of liquid resin. This technology enables structures with precise microscale features to be prepared directly from a computer model. In this review, use of stereolithography for processing trimethylene carbonate, polycaprolactone, and poly(D,L-lactide) poly(propylene fumarate)-based materials is considered. In addition, incorporation of bioceramic fillers for fabrication of bioceramic scaffolds is reviewed. Use of stereolithography for processing of patient-specific implantable scaffolds is also discussed. In addition, use of photopolymerization-based rapid prototyping technology, known as two-photon polymerization, for production of tissue engineering scaffolds with smaller features than conventional stereolithography technology is considered.}, number={3}, journal={JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE}, author={Skoog, Shelby A. and Goering, Peter L. and Narayan, Roger J.}, year={2014}, month={Mar}, pages={845–856} }
 @article{gittard_chen_xu_ovsianikov_chichkov_monteiro-riviere_narayan_2013, title={The effects of geometry on skin penetration and failure of polymer microneedles}, volume={27}, ISSN={["1568-5616"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84874631649&partnerID=MN8TOARS}, DOI={10.1080/01694243.2012.705101}, abstractNote={Microneedles are small-scale devices that may be used for drug delivery and biosensing. In this study, the forces required for mechanical failure, the modes of mechanical failure, as well as the mechanisms for microneedle penetration into porcine skin were examined. Microneedles produced from the acrylate-based polymer e-Shell 200 using an indirect rapid prototyping approach involving two-photon polymerization and poly(dimethylsiloxane) micromolding were found to possess sufficient strength for penetration of porcine skin. The failure forces were an order of magnitude greater than the forces necessary for full insertion into the skin. Bending was the most common form of failure; an increasing aspect ratio and a decreasing tip diameter were associated with lower failure forces. Video captured during skin penetration revealed that microneedle penetration into the skin occurred by means of a series of insertions and not by means of a single insertion event. Images obtained during and after skin penetration confirmed microneedle penetration of skin as well as transdermal delivery of lucifer yellow dye. These findings shed insight into the mechanisms of microneedle penetration and failure, facilitating design improvements for polymer microneedles.}, number={3}, journal={JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY}, author={Gittard, Shaun D. and Chen, Bo and Xu, Huadong and Ovsianikov, Aleksandr and Chichkov, Boris N. and Monteiro-Riviere, Nancy A. and Narayan, Roger J.}, year={2013}, month={Feb}, pages={227–243} }
 @article{bayati_alipour_joshi_molaei_narayan_narayan_misture_2013, title={Thin-Film Epitaxy and Enhancement of Photocatalytic Activity of Anatase/Zirconia Heterostructures by Nanosecond Excimer Laser Treatment}, volume={117}, ISSN={["1932-7447"]}, DOI={10.1021/jp400545t}, abstractNote={We present a novel method to improve the photocatalytic efficiency of epitaxial c-axis anatase TiO2 thin films by a factor of 2 by using nanosecond laser annealing. The anatase films were epitaxially grown by pulsed laser deposition on Si(001) substrates, where a tetragonal yttria-stabilized zirconia (t-YSZ) buffer was used to effectively remove the native SiOx layer from the substrates prior to deposition of anatase. With the information from X-ray and TEM diffraction patterns, the epitaxial relationship across the interfaces was shown to be: (001)[110]anatase||(001)[110]t-YSZ||(001)[001]silicon. Performing high-temperature XRD, we observed that the anatase epilayers were stable up to 1100 °C, far beyond the normal anatase-to-rutile transition temperature (approximately 600–700 °C). The samples were subsequently laser-annealed in air by a single pulse of KrF excimer laser beam at an energy density of ∼0.3 J.cm–2. On the basis of the detailed HRTEM studies, the interface between the laser annealed and the...}, number={14}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Bayati, M. R. and Alipour, H. M. and Joshi, S. and Molaei, R. and Narayan, R. J. and Narayan, J. and Misture, S. T.}, year={2013}, month={Apr}, pages={7138–7147} }
 @article{bayati_joshi_molaei_narayan_narayan_2013, title={Ultrafast switching in wetting properties of TiO2/YSZ/Si(001) epitaxial heterostructures induced by laser irradiation}, volume={113}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.4790327}, DOI={10.1063/1.4790327}, abstractNote={We have demonstrated dark hydrophilicity of single crystalline rutile TiO2(100) thin films, in which rapid switching from a hydrophobic to a hydrophilic surface was achieved using nanosecond excimer laser irradiation. The TiO2/YSZ/Si(001) single crystalline heterostructures were grown by pulsed laser deposition and were subsequently irradiated by a single pulse of a KrF excimer laser at several energies. The wettability of water on the surfaces of the samples was evaluated. The samples were hydrophobic prior to laser annealing and turned hydrophilic after laser annealing. Superhydrophilic surfaces were obtained at higher laser energy densities (e.g., 0.32 J.cm−2). The stoichiometries of the surface regions of the samples before and after laser annealing were examined using XPS. The results revealed the formation of oxygen vacancies on the surface, which are surmised to be responsible for the observed superhydrophilic behavior. According to the AFM images, surface smoothening was greater in films that were annealed at higher laser energy densities. The samples exhibited hydrophobic behavior after being placed in ambient atmosphere. The origin of laser induced wetting behavior was qualitatively understood to stem from an increase of point defects near the surface, which lowered the film/water interfacial energy. This type of rapid hydrophobic/hydrophilic switching may be used to facilitate fabrication of electronic and photonic devices with novel properties.}, number={6}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Bayati, M. R. and Joshi, S. and Molaei, R. and Narayan, R. J. and Narayan, J.}, year={2013}, month={Feb}, pages={063706} }
 @article{skoog_bayati_petrochenko_stafslien_daniels_cilz_comstock_elam_narayan_2012, title={Antibacterial activity of zinc oxide-coated nanoporous alumina}, volume={177}, ISSN={["0921-5107"]}, DOI={10.1016/j.mseb.2012.04.024}, abstractNote={Nanoporous alumina membranes, also known as anodized aluminum oxide membranes, are being investigated for use in treatment of burn injuries and other skin wounds. In this study, atomic layer deposition was used for coating the surfaces of nanoporous alumina membranes with zinc oxide. Agar diffusion assays were used to show activity of zinc oxide-coated nanoporous alumina membranes against several bacteria found on the skin surface, including Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis. On the other hand, zinc oxide-coated nanoporous alumina membranes did not show activity against Pseudomonas aeruginosa, Enterococcus faecalis, and Candida albicans. These results suggest that zinc oxide-coated nanoporous alumina membranes have activity against some Gram-positive and Gram-negative bacteria that are associated with skin colonization and skin infection.}, number={12}, journal={MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS}, author={Skoog, S. A. and Bayati, M. R. and Petrochenko, P. E. and Stafslien, S. and Daniels, J. and Cilz, N. and Comstock, D. J. and Elam, J. W. and Narayan, R. J.}, year={2012}, month={Jul}, pages={992–998} }
 @article{bayati_ding_lee_narayan_narayan_zhou_pennycook_2012, title={Defect mediated photocatalytic decomposition of 4-chlorophenol on epitaxial rutile thin films under visible and UV illumination}, volume={24}, ISSN={0953-8984 1361-648X}, url={http://dx.doi.org/10.1088/0953-8984/24/39/395005}, DOI={10.1088/0953-8984/24/39/395005}, abstractNote={We show that pure rutile TiO2 can be photo-responsive even under low energy visible light after annealing in vacuum where we envisage that the point defects, i.e. oxygen vacancies and titanium interstitials, serve an important role. In this study, single crystal rutile films were grown by the pulsed laser deposition technique and then vacuum annealed under different oxygen pressures to introduce defects into their lattices. 4-chlorophenol was selected as a model material and decomposed by the annealed TiO2 films where the maximum photocatalytic reaction rate constants were determined as 0.0107 and 0.0072 min−1 under UV and visible illumination. Epitaxial growth along the [200] direction was confirmed by φ-scan and 2θ-scan XRD and the epitaxial relationship between the rutile film and the c-sapphire substrate was explained as ( 1 0 0 ) [ 0 1 0 ] R ‖ ( 0 0 0 1 ) [ 1 2 ̄ 1 0 ] S ?> . The formation of atomically sharp interfaces and the epitaxial growth were ascertained by annular dark-field STEM imaging. Based on the XPS, UV–vis and PL spectroscopy results, it was found that the defect concentration increased after annealing under lower pressures, e.g. 5 × 10−6 Torr. In contrast, more perfect crystals were obtained when the films were annealed under high oxygen pressures, namely 5 × 101 Torr. The morphology of the films was also investigated by employing an AFM technique. It was observed that increase of the annealing pressure results in the formation of larger grains. It was also found that the electrical resistivity of the rutile films strongly increased by about three orders of magnitude when the annealing pressure increased from 5 × 10−4 to 5 × 101 Torr.}, number={39}, journal={Journal of Physics: Condensed Matter}, publisher={IOP Publishing}, author={Bayati, M R and Ding, J and Lee, Y F and Narayan, R J and Narayan, J and Zhou, H and Pennycook, S J}, year={2012}, month={Sep}, pages={395005} }
 @article{bayati_molaei_narayan_narayan_zhou_pennycook_2012, title={Domain epitaxy in TiO2/α-Al2O3 thin film heterostructures with Ti2O3 transient layer}, volume={100}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.4729937}, DOI={10.1063/1.4729937}, abstractNote={Rutile TiO2 films were grown epitaxially on α-alumina (sapphire(0001)) substrates and characterized by x-ray diffraction and scanning transmission electron microscopy. It was revealed that the rutile film initially grows pseudomorphically on sapphire as Ti2O3 and, after a few monolayers, it grows tetragonally on the Ti2O3/sapphire platform. Formation of the Ti2O3 transient layer was attributed to the symmetry mismatch between tetragonal structure of TiO2 and hexagonal structure of alumina. The separation between the ½[101¯](101) misfit dislocations was dictated by Ti2O3 and was determined to be 9.7 Å which is consistent with 4/3 and 3/2 alternating domains across the film/substrate interface.}, number={25}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Bayati, M. R. and Molaei, R. and Narayan, R. J. and Narayan, J. and Zhou, H. and Pennycook, S. J.}, year={2012}, month={Jun}, pages={251606} }
 @article{boehm_miller_singh_shah_stafslien_daniels_narayan_2012, title={Indirect rapid prototyping of antibacterial acid anhydride copolymer microneedles}, volume={4}, ISSN={["1758-5082"]}, DOI={10.1088/1758-5082/4/1/011002}, abstractNote={Microneedles are needle-like projections with microscale features that may be used for transdermal delivery of a variety of pharmacologic agents, including antibacterial agents. In the study described in this paper, an indirect rapid prototyping approach involving a combination of visible light dynamic mask micro-stereolithography and micromolding was used to prepare microneedle arrays out of a biodegradable acid anhydride copolymer, Gantrez® AN 169 BF. Fourier transform infrared spectroscopy, energy dispersive x-ray spectrometry and nanoindentation studies were performed to evaluate the chemical and mechanical properties of the Gantrez® AN 169 BF material. Agar plating studies were used to evaluate the in vitro antimicrobial performance of these arrays against Bacillus subtilis, Candida albicans, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Large zones of growth inhibition were noted for Escherichia coli, S. aureus, Enterococcus faecalis and B. subtilis. The performance of Gantrez® AN 169 BF against several bacteria suggests that biodegradable acid anhydride copolymer microneedle arrays prepared using visible light dynamic mask micro-stereolithography micromolding may be useful for treating a variety of skin infections.}, number={1}, journal={BIOFABRICATION}, author={Boehm, Ryan D. and Miller, Philip R. and Singh, Ritika and Shah, Akash and Stafslien, Shane and Daniels, Justin and Narayan, Roger J.}, year={2012}, month={Mar} }
 @inproceedings{wongwiwat_narayan_lee_2012, title={Laser micromachining modeling and laser machined surface errors prediction for biomedical applications}, DOI={10.1115/msec2012-7370}, abstractNote={This paper presents an analytical modeling and laser micromachining technique of microchannel and micro-structures for bio-devices manufacturing and biomedical applications. The ablation of the laser micromachining with direct-write method has been modeled and simulated for micro-channels or microstructures in bio-devices microfabrication. In this paper, the analytical model was adapted from the linear function for beam propagation in our previous research by using the Gaussian function to improve modeling accuracy. Basically, the new laser ablation model based on Gaussian distribution, beam propagation modeling and Beer’s law were used to formulate and model the laser ablation phenomenon. After the simulation with MATLAB programming, the actual experiment on laser micromachining has been conducted to compare the simulated results with the actual ones. Finally, the purposed modeling technique can be applied in the surface error analysis and biomedical applications. The example case in this paper showed how the modeling could solve the complex phenomenon of the overlapping in laser micromachining.}, booktitle={Proceedings of the ASME International Manufacturing Science and Engineering Conference, 2012}, author={Wongwiwat, P. and Narayan, R. J. and Lee, Yuan-Shin}, year={2012}, pages={59–68} }
 @article{valdés-ramírez_windmiller_claussen_martinez_kuralay_zhou_zhou_polsky_miller_narayan_et al._2012, title={Multiplexed and switchable release of distinct fluids from microneedle platforms via conducting polymer nanoactuators for potential drug delivery}, volume={161}, ISSN={0925-4005}, url={http://dx.doi.org/10.1016/j.snb.2011.11.085}, DOI={10.1016/j.snb.2011.11.085}, abstractNote={We report on the development of a microneedle-based multiplexed drug delivery actuator that enables the controlled delivery of multiple therapeutic agents. Two individually-addressable channels on a single microneedle array, each paired with its own reservoir and conducting polymer nanoactuator, are used to deliver various permutations of two unique chemical species. Upon application of suitable redox potentials to the selected actuator, the conducting polymer is able to undergo reversible volume changes, thereby serving to release a model chemical agent in a controlled fashion through the corresponding microneedle channels. Time-lapse videos offer direct visualization and characterization of the membrane switching capability and, along with calibration investigations, confirm the ability of the device to alternate the delivery of multiple reagents from individual microneedles of the array with higher precision and temporal resolution than conventional drug delivery actuators. Analytical modeling offers prediction of the volumetric flow rate through a single microneedle and accordingly can be used to assist in the design of subsequent microneedle arrays. The robust solid-state design and lack of mechanical components circumvent reliability issues that challenge fragile conventional microelectromechanical drug delivery devices. This proof-of-concept study demonstrates the potential of the drug delivery actuator system to aid in the rapid administration of multiple therapeutic agents and indicates the potential to counteract diverse biomedical conditions.}, number={1}, journal={Sensors and Actuators B: Chemical}, publisher={Elsevier BV}, author={Valdés-Ramírez, Gabriela and Windmiller, Joshua R. and Claussen, Jonathan C. and Martinez, Alexandra G. and Kuralay, Filiz and Zhou, Ming and Zhou, Nandi and Polsky, Ronen and Miller, Philip R. and Narayan, Roger and et al.}, year={2012}, month={Jan}, pages={1018–1024} }
 @article{miller_skoog_edwards_lopez_wheeler_arango_xiao_brozik_wang_polsky_et al._2012, title={Multiplexed microneedle-based biosensor array for characterization of metabolic acidosis}, volume={88}, ISSN={["1873-3573"]}, DOI={10.1016/j.talanta.2011.11.046}, abstractNote={The development of a microneedle-based biosensor array for multiplexed in situ detection of exercise-induced metabolic acidosis, tumor microenvironment, and other variations in tissue chemistry is described. Simultaneous and selective amperometric detection of pH, glucose, and lactate over a range of physiologically relevant concentrations in complex media is demonstrated. Furthermore, materials modified with a cell-resistant (Lipidure®) coating were shown to inhibit macrophage adhesion; no signs of coating delamination were noted over a 48-h period.}, journal={TALANTA}, author={Miller, Philip R. and Skoog, Shelby A. and Edwards, Thayne L. and Lopez, Deanna M. and Wheeler, David R. and Arango, Dulce C. and Xiao, Xiaoyin and Brozik, Susan M. and Wang, Joseph and Polsky, Ronen and et al.}, year={2012}, month={Jan}, pages={739–742} }
 @article{bayati_gupta_molaei_narayan_narayan_2012, title={Phase Tuning, Thin Film Epitaxy, Interfacial Modeling, and Properties of YSZ-Buffered TiO2 on Si(001) Substrate}, volume={12}, ISSN={1528-7483 1528-7505}, url={http://dx.doi.org/10.1021/cg3007124}, DOI={10.1021/cg3007124}, abstractNote={We have studied systematically the influence of pulsed laser deposition variables on microstructure and properties of TiO2 epitaxial thin films where integration with Si(100) substrate was achieved by cubic yttria-stabilized-zirconia (c-YSZ) buffer layer. Details of crystallographic and atomic arrangements across the interfaces are discussed in the light of the domain matching epitaxy paradigm. The single crystalline rutile films were obtained at higher substrate temperatures and lower oxygen pressures; whereas, the growth of epitaxial anatase films was promoted by decreasing the temperature and increasing the oxygen pressure. We showed that crystallographic structure of the TiO2 films is determined mainly by the termination structure of the c-YSZ layer and the bonding characteristics across the TiO2/c-YSZ interface. Using 2θ and φ scans of XRD, the epitaxial relationship between Si(100) substrate and the zirconia buffer layer was shown to be cube-on-cube: (001)[100]YSZ∥(001)[100]Si. Furthermore, the epit...}, number={9}, journal={Crystal Growth & Design}, publisher={American Chemical Society (ACS)}, author={Bayati, M. R. and Gupta, P. and Molaei, R. and Narayan, R. J. and Narayan, J.}, year={2012}, month={Aug}, pages={4535–4544} }
 @article{narayan_2012, title={Recent Developments in Electronic, Functional, and Biological Thin Films}, volume={64}, ISSN={1047-4838 1543-1851}, url={http://dx.doi.org/10.1007/S11837-012-0303-7}, DOI={10.1007/S11837-012-0303-7}, abstractNote={The use of surface modification by humans dates back several millennia. As noted by Myers, the art of Cro-Magnon man in 15,000 B.C. can be considered to be a decorative coating. Oddy noted that applying gold to surfaces has been performed for at least 5000 years. Processing of thin films for applications other than gilding began in earnest in the nineteenth century. At the beginning of the nineteenth century, Luigi Brugnatelli used electroplating to deposit gold; by the middle of that century, deposition of a variety of metals had been demonstrated. Sir Robert Grove described a process that he termed ‘‘cathodic disintegration’’ in 1852; Sir John Thompson later renamed this process ‘‘sputtering.’’ As noted by Mattox, Michael Faraday described sputtering within a glow discharge tube for deposition of films in the mid-nineteenth century. At the turn of the last century, Thomas Edison used sputtering to deposit gold coatings on master wax cylinders, which were subsequently used to produce ‘‘Gold Moulded Records.’’ The origin of chemical vapor deposition has been traced to early studies by von Guericke and Henry. It was used for development of light bulb materials in the 1880s and for purification of refractory metals in the 1940s. Over the past half century, rapid developments in thin film technology were associated with increases in complexity and reductions in size of electronic and optical devices. For example, Smith and Turner used evaporation by a ruby laser to create films of a variety of materials, including As2S3, Ge, MoO3, PbTe, Sb2S3, Se, Te, and ZnTe. Currently, pulsed laser deposition is commonly used for deposition of a variety of thin films, including multicomponent systems and biologically relevant materials, at low temperatures. At the beginning of the twenty-first century, significant thin film research activities involve the development of thin films for medical and energy applications. In this issue, Gupta et al. considered the protein adsorption and wettability of composite materials containing ultrahigh molecular weight polyethylene, hydroxyapatite, alumina, and carbon nanotubes; these materials have potential use in joint replacement prostheses. Palkowski et al. created a three-layered stainless steel/polypropylene copolymer/stainless steel sandwich sheet material with biomimetic properties. Skoog et al. deposited ultrananocrystalline diamond films on microporous silicon nitride membranes using microwave plasma chemical vapor deposition and evaluated the growth of human epidermal keratinocytes on these materials. Shet et al. prepared zinc oxide thin films using radio frequency sputtering in the presence of a gas ambient containing argon and nitrogen. They demonstrated that aligned nanoscale structures with enhanced photoelectrochemical response were prepared under an appropriate gas ambient. It is hoped that this special issue helps to generate discussions in industry, academia, and government regarding use of thin film technology for electronic, functional, and biological applications.}, number={4}, journal={JOM}, publisher={Springer Science and Business Media LLC}, author={Narayan, Roger}, year={2012}, month={Mar}, pages={505–505} }
 @article{bayati_joshi_molaei_narayan_narayan_2012, title={Structure-property correlation in epitaxial (200) rutile films on sapphire substrates}, volume={187}, ISSN={["0022-4596"]}, DOI={10.1016/j.jssc.2012.01.031}, abstractNote={We have investigated the influence of the deposition variables on photocatalytic properties of epitaxial rutile films. Despite a large lattice misfit of rutile with sapphire substrate, (2 0 0) epitaxial layers were grown on (0 0 0 1)sapphire by domain matching epitaxy paradigm. Using φ-scan XRD and cross section TEM, the epitaxial relationship was determined to be rutile(1 0 0)||sapphire(0 0 0 1), rutile(0 0 1)||sapphire(1 0 −1 0), and rutile(0 1 0)||sapphire(1 −2 1 0). Based on the XRD patterns, increasing the repetition rate introduced tensile stress along the film normal direction, which may arise as a result of trapped defects. Formation of such defects was studied by UV–VIS, PL, and XPS techniques. AFM studies showed that the film roughness increases with the repetition rate. Finally, photocatalytic performance of the layers was investigated through measuring decomposition rate of 4-chlorophenol on the films surface. The films grown at higher frequencies revealed higher photocatalytic efficiency. This behavior was mainly related to formation of point defects which enhance the charge separation.}, journal={JOURNAL OF SOLID STATE CHEMISTRY}, author={Bayati, M. R. and Joshi, Sh and Molaei, R. and Narayan, R. J. and Narayan, J.}, year={2012}, month={Mar}, pages={231–237} }
 @article{boehm_chen_gittard_chichkov_monteiro-riviere_nasir_narayan_2014, title={Two-photon polymerization/micromolding of microscale barbs for medical applications}, volume={28}, ISSN={0169-4243 1568-5616}, url={http://dx.doi.org/10.1080/01694243.2012.693828}, DOI={10.1080/01694243.2012.693828}, abstractNote={Tissue barbs are small-scale structures that may be used for sutureless joining of tissues. In this study, several types of tissue barbs were fabricated using two-photon polymerization/micromolding, including two-pronged tissue barbs, eight-pronged tissue barbs, 10-pronged tissue barbs, and 16-pronged tissue barbs. Tissue barb penetration in porcine tissue was observed using confocal laser scanning microscopy. Constructs containing medical tape and tissue barbs were created by applying tissue barbs in a parallel arrangement to Transpore™ medical tape. These results suggest that two-photon polymerization/micromolding is an indirect rapid prototyping approach that may be used for high-throughput replication of tissue barbs and other microstructured solid wound sealants.}, number={3-4}, journal={Journal of Adhesion Science and Technology}, publisher={Informa UK Limited}, author={Boehm, R.D. and Chen, B. and Gittard, S.D. and Chichkov, B.N. and Monteiro-Riviere, N.A. and Nasir, A. and Narayan, R.J.}, year={2014}, month={Feb}, pages={387–398} }
 @article{skoog_sumant_monteiro-riviere_narayan_2012, title={Ultrananocrystalline Diamond-Coated Microporous Silicon Nitride Membranes for Medical Implant Applications}, volume={64}, ISSN={1047-4838 1543-1851}, url={http://dx.doi.org/10.1007/S11837-012-0300-X}, DOI={10.1007/S11837-012-0300-X}, number={4}, journal={JOM}, publisher={Springer Science and Business Media LLC}, author={Skoog, Shelby A. and Sumant, Anirudha V. and Monteiro-Riviere, Nancy A. and Narayan, Roger J.}, year={2012}, month={Apr}, pages={520–525} }
 @article{hyde_stewart_scarel_parsons_shih_shih_lin_su_monteiro-riviere_narayan_et al._2011, title={Atomic layer deposition of titanium dioxide on cellulose acetate for enhanced hemostasis}, volume={6}, ISSN={1860-6768}, url={http://dx.doi.org/10.1002/biot.201000342}, DOI={10.1002/biot.201000342}, abstractNote={AbstractTiO2 films may be used to alter the wettability and hemocompatibility of cellulose materials. In this study, pure and stoichiometric TiO2 films were grown using atomic layer deposition on both silicon and cellulose substrates. The films were grown with uniform thicknesses and with a growth rate in agreement with literature results. The TiO2 films were shown to profoundly alter the water contact angle values of cellulose in a manner dependent upon processing characteristics. Higher amounts of protein adsorption indicated by blurry areas on images generated by scanning electron microscopy were noted on TiO2‐coated cellulose acetate than on uncoated cellulose acetate. These results suggest that atomic layer deposition is an appropriate method for improving the biological properties of hemostatic agents and other blood‐contacting biomaterials.}, number={2}, journal={Biotechnology Journal}, publisher={Wiley}, author={Hyde, G. Kevin and Stewart, S. Michael and Scarel, Giovanna and Parsons, Gregory N. and Shih, Chun-Che and Shih, Chun-Ming and Lin, Shing-Jong and Su, Yea-Yang and Monteiro-Riviere, Nancy A. and Narayan, Roger J. and et al.}, year={2011}, month={Feb}, pages={213–223} }
 @article{windmiller_valdés-ramírez_zhou_zhou_miller_jin_brozik_polsky_katz_narayan_et al._2011, title={Bicomponent Microneedle Array Biosensor for Minimally-Invasive Glutamate Monitoring}, volume={23}, ISSN={1040-0397}, url={http://dx.doi.org/10.1002/elan.201100361}, DOI={10.1002/elan.201100361}, abstractNote={AbstractThis article describes the design of a new and attractive minimally‐invasive bicomponent microneedle sensing device for the electrochemical monitoring of the excitatory neurotransmitter glutamate and glucose. The new device architecture relies on the close integration of solid and hollow microneedles into a single biosensor array device containing multiple microcavities. Such microcavities facilitate the electropolymeric entrapment of the recognition enzyme within each microrecess. The resulting microneedle biosensor array can be employed as a minimally‐invasive on‐body transdermal patch, obviating the extraction/sampling of the biological fluid, thereby simplifying device requirements. The new concept is demonstrated for the electropolymeric entrapment of glutamate oxidase and glucose oxidase within a poly(o‐phenylenediamine) (PPD) thin film. The PPD‐based enzyme entrapment methodology enables the effective rejection of coexisting electroactive interferents without compromising the sensitivity or response time of the device. The resulting microneedle‐based glutamate and glucose biosensors thus exhibit high selectivity, sensitivity, speed, and stability in both buffer and undiluted human serum. High‐fidelity glutamate measurements down to the 10 µM level are obtained in serum. The attractive recess design also serves to protect the enzyme layer upon insertion into the skin. This simple, yet robust microneedle design is well‐suited for diverse biosensing applications in which real‐time metabolite monitoring is a core requirement.}, number={10}, journal={Electroanalysis}, publisher={Wiley}, author={Windmiller, Joshua Ray and Valdés-Ramírez, Gabriela and Zhou, Nandi and Zhou, Ming and Miller, Philip R. and Jin, Chunming and Brozik, Susan M. and Polsky, Ronen and Katz, Evgeny and Narayan, Roger and et al.}, year={2011}, month={Sep}, pages={2302–2309} }
 @article{cristescu_popescu_socol_visan_mihailescu_gittard_miller_martin_narayan_andronie_et al._2011, title={Deposition of antibacterial of poly(1,3-bis-(p-carboxyphenoxy propane)-co-(sebacic anhydride)) 20:80/gentamicin sulfate composite coatings by MAPLE}, volume={257}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2010.11.141}, abstractNote={We report on thin film deposition of poly(1,3-bis-(p-carboxyphenoxy propane)-co-sebacic anhydride)) 20:80 thin films containing several gentamicin concentrations by matrix assisted pulsed laser evaporation (MAPLE). A pulsed KrF* excimer laser was used to deposit the polymer–drug composite thin films. Release of gentamicin from these MAPLE-deposited polymer conjugate structures was assessed. Fourier transform infrared spectroscopy was used to demonstrate that the functional groups of the MAPLE-transferred materials were not changed by the deposition process nor were new functional groups formed. Scanning electron microscopy confirmed that MAPLE may be used to fabricate thin films of good morphological quality. The activity of gentamicin-doped films against Escherichia coli and Staphylococcus aureus bacteria was demonstrated using disk diffusion and antibacterial drop test. Our studies indicate that deposition of polymer–drug composite thin films prepared by MAPLE is a suitable technique for performing controlled drug delivery. Antimicrobial thin film coatings have several medical applications, including use for indwelling catheters and implanted medical devices.}, number={12}, journal={APPLIED SURFACE SCIENCE}, author={Cristescu, R. and Popescu, C. and Socol, G. and Visan, A. and Mihailescu, I. N. and Gittard, S. D. and Miller, P. R. and Martin, T. N. and Narayan, R. J. and Andronie, A. and et al.}, year={2011}, month={Apr}, pages={5287–5292} }
 @article{gittard_miller_jin_martin_boehm_chisholm_stafslien_daniels_cilz_monteiro-riviere_et al._2011, title={Deposition of antimicrobial coatings on microstereolithography-fabricated microneedles}, volume={63}, ISSN={["1543-1851"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000291610800011&KeyUID=WOS:000291610800011}, DOI={10.1007/s11837-011-0093-3}, number={6}, journal={JOM}, author={Gittard, Shaun D. and Miller, Philip R. and Jin, Chunming and Martin, Timothy N. and Boehm, Ryan D. and Chisholm, Bret J. and Stafslien, Shane J. and Daniels, Justin W. and Cilz, Nicholas and Monteiro-Riviere, Nancy A. and et al.}, year={2011}, month={Jun}, pages={59–68} }
 @article{yang_mal_jin_narayan_narayan_2011, title={Epitaxial VO2/Cr2O3/sapphire heterostructure for multifunctional applications}, volume={98}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.3541649}, DOI={10.1063/1.3541649}, abstractNote={In this letter, we report integration of magnetic and ultrafast-transition properties of VO2 films with antiferromagnetic (AFM) Cr2O3 template layer in the epitaxial VO2/Cr2O3/Al2O3 heterostructure The Cr2O3 is an AFM material, which can pin the spin momentum of ferromagnetic VO2, in addition to providing epitaxial template. Thus, the magnetic properties of VO2 films grown with Cr2O3 buffer layer can be improved for multifunctional magnetic tunnel junctions and sensor applications. Electrical resistivity measurements as a function of temperature showed a sharp transition width (1.94 °C), with a small hysteresis width (5.7 °C), and large resistance change (∼3.8×104) across the semiconductor to metal transition (SMT). We discuss the correlations of the magnetic properties and SMT characteristics with epitaxial growth and formation of twins.}, number={2}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Yang, Tsung-Han and Mal, S. and Jin, C. and Narayan, R. J. and Narayan, J.}, year={2011}, month={Jan}, pages={022105} }
 @article{miller_gittard_edwards_lopez_xiao_wheeler_monteiro-riviere_brozik_polsky_narayan_2011, title={Integrated carbon fiber electrodes within hollow polymer microneedles for transdermal electrochemical sensing}, volume={5}, ISSN={1932-1058}, url={http://dx.doi.org/10.1063/1.3569945}, DOI={10.1063/1.3569945}, abstractNote={In this study, carbon fiber electrodes were incorporated within a hollow microneedle array, which was fabricated using a digital micromirror device-based stereolithography instrument. Cell proliferation on the acrylate-based polymer used in microneedle fabrication was examined with human dermal fibroblasts and neonatal human epidermal keratinocytes. Studies involving full-thickness cadaveric porcine skin and trypan blue dye demonstrated that the hollow microneedles remained intact after puncturing the outermost layer of cadaveric porcine skin. The carbon fibers underwent chemical modification in order to enable detection of hydrogen peroxide and ascorbic acid; electrochemical measurements were demonstrated using integrated electrode-hollow microneedle devices.}, number={1}, journal={Biomicrofluidics}, publisher={AIP Publishing}, author={Miller, Philip R. and Gittard, Shaun D. and Edwards, Thayne L. and Lopez, DeAnna M. and Xiao, Xiaoyin and Wheeler, David R. and Monteiro-Riviere, Nancy A. and Brozik, Susan M. and Polsky, Ronen and Narayan, Roger J.}, year={2011}, month={Mar}, pages={013415} }
 @article{mccullen_gittard_miller_pourdeyhimi_narayan_loboa_2011, title={Laser Ablation Imparts Controlled Micro-Scale Pores in Electrospun Scaffolds for Tissue Engineering Applications}, volume={39}, ISSN={0090-6964 1573-9686}, url={http://dx.doi.org/10.1007/S10439-011-0378-2}, DOI={10.1007/S10439-011-0378-2}, abstractNote={Electrospun scaffolds have been used extensively for tissue engineering applications due to the simple processing scheme and versatility. However, many additional benefits can be imparted to these materials via post-processing techniques. Specifically the addition of structured pores on the micro-scale can offer a method to enable patterned cell adhesion, enhanced diffusional properties, and/or guide vascular infiltration upon implantation in vivo. In this study, we laser ablated electrospun poly(L: -lactic acid) (PLA) scaffolds and assessed the ablation process and cellular interaction by examining human adipose-derived stem cell (hASC) viability and proliferation on laser micro-machined scaffolds. Laser ablated pores of 150, 300, and 600 μm diameter were micro-machined through electrospun PLA scaffolds. Laser ablation parameters were varied and it was determined that the aperture and z-travel direction of the laser linearly correlated with the ablated pore diameter. To assess cytocompatibility of the micro-machined scaffolds, hASCs were seeded on each scaffold and cell viability was assessed on day 7. Human ASCs were able to adhere around the micro-machined features. DNA content was quantified on all scaffolds and it was determined that hASCs were able to proliferate on all scaffolds. The process of laser ablation could impart many beneficial features to electrospun scaffolds by increasing mass transport and mimicking micro-scale features and assisting in patterning of cells around micro-machined features.}, number={12}, journal={Annals of Biomedical Engineering}, publisher={Springer Science and Business Media LLC}, author={McCullen, S. D. and Gittard, S. D. and Miller, P. R. and Pourdeyhimi, Behnam and Narayan, R. J. and Loboa, E. G.}, year={2011}, month={Aug}, pages={3021–3030} }
 @article{narayan_boehm_sumant_2011, title={Medical applications of diamond particles & surfaces}, volume={14}, ISSN={1369-7021}, url={http://dx.doi.org/10.1016/S1369-7021(11)70087-6}, DOI={10.1016/S1369-7021(11)70087-6}, abstractNote={Diamond has been considered for use in several medical applications due to its unique mechanical, chemical, optical, and biological properties. In this paper, methods for preparing synthetic diamond surfaces and particles are described. In addition, recent developments involving the use of diamond in prostheses, sensing, imaging, and drug delivery applications are reviewed. These developments suggest that diamond-containing structures will provide significant improvements in the diagnosis and treatment of medical conditions over the coming years.}, number={4}, journal={Materials Today}, publisher={Elsevier BV}, author={Narayan, Roger J and Boehm, Ryan D. and Sumant, Anirudha V.}, year={2011}, month={Apr}, pages={154–163} }
 @article{windmiller_zhou_chuang_valdes-ramirez_santhosh_miller_narayan_wang_2011, title={Microneedle array-based carbon paste amperometric sensors and biosensors}, volume={136}, ISSN={["0003-2654"]}, DOI={10.1039/c1an00012h}, abstractNote={The design and characterization of a microneedle array-based carbon paste electrode towards minimally invasive electrochemical sensing are described. Arrays consisting of 3 × 3 pyramidal microneedle structures, each with an opening of 425 µm, were loaded with a metallized carbon paste transducer. The renewable nature of carbon paste electrodes enables the convenient packing of hollow non-planar microneedles with pastes that contain assorted catalysts and biocatalysts. Smoothing the surface results in good microelectrode-to-microelectrode uniformity. Optical and scanning electron micrographs shed useful insights into the surface morphology at the microneedle apertures. The attractive performance of the novel microneedle electrode arrays is illustrated in vitro for the low-potential detection of hydrogen peroxide at rhodium-dispersed carbon paste microneedles and for lactate biosensing by the inclusion of lactate oxidase in the metallized carbon paste matrix. Highly repeatable sensing is observed following consecutive cycles of packing/unpacking the carbon paste. The operational stability of the array is demonstrated as well as the interference-free detection of lactate in the presence of physiologically relevant levels of ascorbic acid, uric acid, and acetaminophen. Upon addressing the biofouling effects associated with on-body sensing, the microneedle carbon paste platform would be attractive for the subcutaneous electrochemical monitoring of a number of physiologically relevant analytes.}, number={9}, journal={ANALYST}, author={Windmiller, Joshua Ray and Zhou, Nandi and Chuang, Min-Chieh and Valdes-Ramirez, Gabriela and Santhosh, Padmanabhan and Miller, Philip R. and Narayan, Roger and Wang, Joseph}, year={2011}, pages={1846–1851} }
 @article{boehm_miller_hayes_monteiro-riviere_narayan_2011, title={Modification of microneedles using inkjet printing}, volume={1}, ISSN={2158-3226}, url={http://dx.doi.org/10.1063/1.3602461}, DOI={10.1063/1.3602461}, abstractNote={In this study, biodegradable acid anhydride copolymer microneedles containing quantum dots were fabricated by means of visible light dynamic mask micro-stereolithography-micromolding and inkjet printing. Nanoindentation was performed to obtain the hardness and the Young's modulus of the biodegradable acid anhydride copolymer. Imaging of quantum dots within porcine skin was accomplished by means of multiphoton microscopy. Our results suggest that the combination of visible light dynamic mask micro-stereolithography-micromolding and inkjet printing enables fabrication of solid biodegradable microneedles with a wide range of geometries as well as a wide range of pharmacologic agent compositions.}, number={2}, journal={AIP Advances}, publisher={AIP Publishing}, author={Boehm, R D and Miller, P R and Hayes, S L and Monteiro-Riviere, N A and Narayan, R J}, year={2011}, pages={022139} }
 @article{gittard_miller_boehm_ovsianikov_chichkov_heiser_gordon_monteiro-riviere_narayan_2011, title={Multiphoton microscopy of transdermal quantum dot delivery using two photon polymerization-fabricated polymer microneedles}, volume={149}, ISSN={["1364-5498"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000285924900015&KeyUID=WOS:000285924900015}, DOI={10.1039/c005374k}, abstractNote={Due to their ability to serve as fluorophores and drug delivery vehicles, quantum dots are a powerful tool for theranostics-based clinical applications. In this study, microneedle devices for transdermal drug delivery were fabricated by means of two-photon polymerization of an acrylate-based polymer. We examined proliferation of cells on this polymer using neonatal human epidermal keratinocytes and human dermal fibroblasts. The microneedle device was used to inject quantum dots into porcine skin; imaging of the quantum dots was performed using multiphoton microscopy.}, journal={FARADAY DISCUSSIONS}, author={Gittard, Shaun D. and Miller, Philip R. and Boehm, Ryan D. and Ovsianikov, Aleksandr and Chichkov, Boris N. and Heiser, Jeremy and Gordon, John and Monteiro-Riviere, Nancy A. and Narayan, Roger J.}, year={2011}, pages={171–185} }
 @article{ovsianikov_malinauskas_schlie_chichkov_gittard_narayan_loebler_sternberg_schmitz_haverich_2011, title={Three-dimensional laser micro- and nano-structuring of acrylated poly(ethylene glycol) materials and evaluation of their cytoxicity for tissue engineering applications}, volume={7}, ISSN={["1878-7568"]}, DOI={10.1016/j.actbio.2010.10.023}, abstractNote={The natural cell environment is characterized by complex three-dimensional structures, which contain features at multiple length scales. Many in vitro studies of cell behavior in three dimensions rely on the availability of artificial scaffolds with controlled three-dimensional topologies. In this paper, we demonstrate fabrication of three-dimensional scaffolds for tissue engineering out of poly(ethylene glycol) diacrylate (PEGda) materials by means of two-photon polymerization (2PP). This laser nanostructuring approach offers unique possibilities for rapid manufacturing of three-dimensional structures with arbitrary geometries. The spatial resolution dependence on the applied irradiation parameters is investigated for two PEGda formulations, which are characterized by molecular weights of 302 and 742. We demonstrate that minimum feature sizes of 200nm are obtained in both materials. In addition, an extensive study of the cytotoxicity of the material formulations with respect to photoinitiator type and photoinitiator concentration is undertaken. Aqueous extracts from photopolymerized PEGda samples indicate the presence of water-soluble molecules, which are toxic to fibroblasts. It is shown that sample aging in aqueous medium reduces the cytotoxicity of these extracts; this mechanism provides a route for biomedical applications of structures generated by 2PP microfabrication and photopolymerization technologies in general. Finally, a fully biocompatible combination of PEGda and a photoinitiator is identified. Fabrication of reproducible scaffold structures is very important for systematic investigation of cellular processes in three dimensions and for better understanding of in vitro tissue formation. The results of this work suggest that 2PP may be used to polymerize poly(ethylene glycol)-based materials into three-dimensional structures with well-defined geometries that mimic the physical and biological properties of native cell environments.}, number={3}, journal={ACTA BIOMATERIALIA}, author={Ovsianikov, A. and Malinauskas, M. and Schlie, S. and Chichkov, B. and Gittard, S. and Narayan, R. and Loebler, M. and Sternberg, K. and Schmitz, K. -P. and Haverich, A.}, year={2011}, month={Mar}, pages={967–974} }
 @article{narayan_adiga_pellin_curtiss_stafslien_chisholm_monteiro-riviere_brigmon_elam_2010, title={Atomic layer deposition of nanoporous biomaterials}, volume={13}, ISSN={["1873-4103"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77949425892&partnerID=MN8TOARS}, DOI={10.1016/s1369-7021(10)70035-3}, abstractNote={Due to its chemical stability, uniform pore size, and high pore density, nanoporous alumina is being investigated for use in biosensing, drug delivery, hemodialysis, and other medical applications. In recent work, we have examined the use of atomic layer deposition for coating the surfaces of nanoporous alumina membranes. Zinc oxide coatings were deposited on nanoporous alumina membranes using atomic layer deposition. The zinc oxide-coated nanoporous alumina membranes demonstrated antimicrobial activity against Escherichia coli and Staphylococcus aureus bacteria. These results suggest that atomic layer deposition is an attractive technique for modifying the surfaces of nanoporous alumina membranes and other nanostructured biomaterials.}, number={3}, journal={MATERIALS TODAY}, author={Narayan, Roger J. and Adiga, Shashishekar P. and Pellin, Michael J. and Curtiss, Larry A. and Stafslien, Shane and Chisholm, Bret and Monteiro-Riviere, Nancy A. and Brigmon, Robin L. and Elam, Jeffrey W.}, year={2010}, month={Mar}, pages={60–64} }
 @article{narayan_adiga_pellin_curtiss_hryn_stafslien_chisholm_shih_shih_lin_et al._2010, title={Atomic layer deposition-based functionalization of materials for medical and environmental health applications}, volume={368}, ISSN={["1471-2962"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000275810800010&KeyUID=WOS:000275810800010}, DOI={10.1098/rsta.2010.0011}, abstractNote={
            Nanoporous alumina membranes exhibit high pore densities, well-controlled and uniform pore sizes, as well as straight pores. Owing to these unusual properties, nanoporous alumina membranes are currently being considered for use in implantable sensor membranes and water purification membranes. Atomic layer deposition is a thin-film growth process that may be used to modify the pore size in a nanoporous alumina membrane while retaining a narrow pore distribution. In addition, films deposited by means of atomic layer deposition may impart improved biological functionality to nanoporous alumina membranes. In this study, zinc oxide coatings and platinum coatings were deposited on nanoporous alumina membranes by means of atomic layer deposition. PEGylated nanoporous alumina membranes were prepared by self-assembly of 1-mercaptoundec-11-yl hexa(ethylene glycol) on platinum-coated nanoporous alumina membranes. The pores of the PEGylated nanoporous alumina membranes remained free of fouling after exposure to human platelet-rich plasma; protein adsorption, fibrin networks and platelet aggregation were not observed on the coated membrane surface. Zinc oxide-coated nanoporous alumina membranes demonstrated activity against two waterborne pathogens,
            Escherichia coli
            and
            Staphylococcus aureus
            . The results of this work indicate that nanoporous alumina membranes may be modified using atomic layer deposition for use in a variety of medical and environmental health applications.
          }, number={1917}, journal={PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES}, author={Narayan, Roger J. and Adiga, Shashishekar P. and Pellin, Michael J. and Curtiss, Larry A. and Hryn, Alexander J. and Stafslien, Shane and Chisholm, Bret and Shih, Chun-Che and Shih, Chun-Ming and Lin, Shing-Jong and et al.}, year={2010}, month={Apr}, pages={2033–2064} }
 @article{doraiswamy_ovsianikov_gittard_monteiro-riviere_crombez_montalvo_shen_chichkov_narayan_2010, title={Fabrication of Microneedles Using Two Photon Polymerization for Transdermal Delivery of Nanomaterials}, volume={10}, ISSN={["1533-4899"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000280361400003&KeyUID=WOS:000280361400003}, DOI={10.1166/jnn.2010.2636}, abstractNote={Microneedle devices for transdermal delivery of nanoscale pharmacologic agents were fabricated out of organically-modified ceramic (Ormocer) materials using two photon polymerization. Out-of-plane hollow microneedle arrays with various aspect ratios were fabricated using this rapid prototyping process. Human epidermal keratinocyte (HEK) viability on Ormocer surfaces fabricated using two photon polymerization was similar to that on control surfaces. Nanoindentation studies were performed to determine hardness and Young's modulus values for Ormocer materials. Microneedies were shown to enable more rapid distribution of the PEG-amine quantum dot solution to the deep epidermis and dermis layers of porcine skin than topical administration. Our results suggest that two photon polymerization may be used to create microneedle arrays for transdermal delivery of nanoscale pharmacologic agents.}, number={10}, journal={JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY}, author={Doraiswamy, Anand and Ovsianikov, Aleksandr and Gittard, Shaun D. and Monteiro-Riviere, Nancy A. and Crombez, Rene and Montalvo, Eva and Shen, Weidian and Chichkov, Boris N. and Narayan, Roger J.}, year={2010}, month={Oct}, pages={6305–6312} }
 @article{ravindra_michael_narayan_kim_krumdick_2011, title={Foreword}, volume={42}, ISSN={1073-5623 1543-1940}, url={http://dx.doi.org/10.1007/S11661-010-0582-Y}, DOI={10.1007/S11661-010-0582-Y}, abstractNote={A total of 30 talks}, number={11}, journal={Metallurgical and Materials Transactions A}, publisher={Springer Science and Business Media LLC}, author={Ravindra, Nuggehalli M. and Michael, Nancy and Narayan, Roger and Kim, Choong-Un and Krumdick, Gregory}, year={2011}, month={Nov}, pages={3249–3249} }
 @article{lin_narayan_lee_2010, title={Hybrid client–server architecture and control techniques for collaborative product development using haptic interfaces}, volume={61}, ISSN={0166-3615}, url={http://dx.doi.org/10.1016/j.compind.2009.07.004}, DOI={10.1016/j.compind.2009.07.004}, abstractNote={In this paper, a collaborative product development and prototyping framework is proposed by using distributed haptic interfaces along with deformable objects modeling. Collaborative Virtual Environment (CVE) is a promising technique for industrial product development and virtual prototyping. Network control problems such as network traffic and network delay in communication have greatly limited collaborative virtual environment applications. The problems become more difficult when high-update-rate haptic interfaces and computation intensive deformable objects modeling are integrated into CVEs for intuitive manipulation and enhanced realism. A hybrid network architecture is proposed to balance the computational burden of haptic rendering and deformable object simulation. Adaptive artificial time compensation is used to reduce the time discrepancy between the server and the client. Interpolation and extrapolation approaches are used to synchronize graphic and haptic data transmitted over the network. The proposed techniques can be used for collaborative product development, virtual assembly, remote product simulation and other collaborative virtual environments where both haptic interfaces and deformable object models are involved.}, number={1}, journal={Computers in Industry}, publisher={Elsevier BV}, author={Lin, Shiyong and Narayan, Roger J. and Lee, Yuan-Shin}, year={2010}, month={Jan}, pages={83–96} }
 @inproceedings{wongwiwat_narayan_lee_2011, title={Improving biocompatibily of laser micromachined silicon wafer by surface coating with poly(ethylene glycol) diacrylate and diamond-like carbon for biomedical devices}, DOI={10.1115/msec2010-34283}, abstractNote={This paper presents a study of laser micromachining and the effect of the micromachined regions on the biocompatibility in the protein adsorption for medical devices applications. From the study, the surface roughness on the micromachined area promoted the protein adsorption so it probably causes the thrombus formation for the application in the cardiovascular or blood related devices. In contrast, this incident can enhance the cell promotion that is helpful for the biomedical implant MEMS devices. To modify the surface property in biocompatibility, both Diamond-like carbon (DLC) coating and Poly ethylene glycol diacrylate (PEGDA), the protein resistant and biocompatible materials, were proposed in this research. The UV lithography for coating PEGDA and Pulse laser deposition for coating DLC on the laser micromachined substrates were applied while the coated substrates were biocompatibility tested with the Bovine Serum Albumin (BSA) to observe the protein adsorption. To image the quantity of adsorption, the fluorescein labeled BSA was used for fluorescent microscope to clearly image the reflective light. This study proposed a good opportunity for major novel techniques such as laser micromachining, PLD and UV lithography in developing and prototyping biocompatible MEMS devices.}, booktitle={Proceedings of the ASME International Manufacturing Science and Engineering Conference 2010, vol 2}, author={Wongwiwat, P. and Narayan, R. J. and Lee, Yuan-Shin}, year={2011}, pages={273–280} }
 @article{doraiswamy_crombez_shen_lee_narayan_2010, title={Inkjet Printing of Cyanoacrylate Adhesive}, volume={86}, ISSN={0021-8464 1545-5823}, url={http://dx.doi.org/10.1080/00218460903417651}, DOI={10.1080/00218460903417651}, abstractNote={In this study, we have demonstrated the use of piezoelectric inkjet printing to fabricate microscale patterns of Vetbond® n-butyl cyanoacrylate tissue adhesive. Optical microscopy, atomic force microscopy, nanoindentation, and a cell viability assay were used to examine the structural, mechanical, and biological properties of microscale cyanoacrylate patterns. The ability to rapidly fabricate microscale patterns of medical and veterinary adhesives will enable reduced bond lines between tissues, improved tissue integrity, and reduced toxicity. We envision that piezoelectric inkjet deposition of cyanoacrylates and other medical adhesives may be used to enhance wound repair in microvascular surgery.}, number={1}, journal={The Journal of Adhesion}, publisher={Informa UK Limited}, author={Doraiswamy, Anand and Crombez, Rene and Shen, Weidian and Lee, Yuan-Shin and Narayan, Roger J.}, year={2010}, month={Jan}, pages={1–9} }
 @article{jin_aggarwal_wei_nori_kumar_ponarin_smirnov_narayan_narayan_2011, title={Intrinsic Room-Temperature Ferromagnetic Properties of Ni-Doped ZnO Thin Films}, volume={42}, ISSN={1073-5623 1543-1940}, url={http://dx.doi.org/10.1007/S11661-010-0479-9}, DOI={10.1007/S11661-010-0479-9}, number={11}, journal={Metallurgical and Materials Transactions A}, publisher={Springer Science and Business Media LLC}, author={Jin, C. and Aggarwal, R. and Wei, W. and Nori, S. and Kumar, D. and Ponarin, D. and Smirnov, A. I. and Narayan, J. and Narayan, R. J.}, year={2011}, month={Nov}, pages={3250–3254} }
 @article{narayan_doraiswamy_chrisey_chichkov_2010, title={Medical prototyping using two photon polymerization}, volume={13}, ISSN={["1873-4103"]}, DOI={10.1016/s1369-7021(10)70223-6}, abstractNote={Two photon polymerization involves nearly simultaneous absorption of ultrashort laser pulses for selective curing of photosensitive material. This process has recently been used to create small-scale medical devices out of several classes of photosensitive materials, such as acrylate-based polymers, organically-modified ceramic materials, zirconium sol-gels, and titanium-containing hybrid materials. In this review, the use of two photon polymerization for fabrication of several types of small-scale medical devices, including microneedles, artificial tissues, microfluidic devices, pumps, sensors, and valves, from computer models is described. Necessary steps in the development of two photon polymerization as a commercially viable medical device manufacturing method are also considered.}, number={12}, journal={MATERIALS TODAY}, author={Narayan, Roger J. and Doraiswamy, Anand and Chrisey, Douglas B. and Chichkov, Boris N.}, year={2010}, month={Dec}, pages={42–48} }
 @article{koroleva_schlie_fadeeva_gittard_miller_ovsianikov_koch_narayan_chichkov_2010, title={Microreplication of laser-fabricated surface and three-dimensional structures}, volume={12}, ISSN={["2040-8986"]}, DOI={10.1088/2040-8978/12/12/124009}, abstractNote={The fabrication of defined surface topographies and three-dimensional structures is a challenging process for various applications, e.g. in photonics and biomedicine. Laser-based technologies provide a promising approach for the production of such structures. The advantages of femtosecond laser ablation and two-photon polymerization for microstructuring are well known. However, these methods cannot be applied to all materials and are limited by their high cost and long production time. In this study, biomedical applications of an indirect rapid prototyping, molding microreplication of laser-fabricated two- and three-dimensional structures are examined. We demonstrate that by this method any laser-generated surface topography as well as three-dimensional structures can be replicated in various materials without losing the original geometry. The replication into multiple copies enables fast and perfect reproducibility of original microstructures for investigations of cell–surface interactions. Compared to unstructured materials, we observe that microstructures have strong influence on morphology and localization of fibroblasts, whereas neuroblastoma cells are not negatively affected.}, number={12}, journal={JOURNAL OF OPTICS}, author={Koroleva, Anastasia and Schlie, Sabrina and Fadeeva, Elena and Gittard, Shaun D. and Miller, Philip and Ovsianikov, Aleksandr and Koch, Juergen and Narayan, Roger J. and Chichkov, Boris N.}, year={2010}, month={Dec} }
 @article{doraiswamy_crombez_shen_lee_narayan_2010, title={Microscale Patterning of Two-Component Biomedical Hydrogel}, volume={86}, ISSN={0021-8464 1545-5823}, url={http://dx.doi.org/10.1080/00218460903417875}, DOI={10.1080/00218460903417875}, abstractNote={In this study, piezoelectric inkjet technology was used for microscale patterning of a two-component medical hydrogel (sold under the registered trademark Coseal®). A MEMS-based piezoelectric actuator was used to control the flow of polyethylene glycol in a sodium phosphate/sodium carbonate solution through inkjet nozzles. A hydrogen chloride solution was subsequently used to cross-link the polyethylene glycol material. Optical microscopy, scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and nanoindentation studies were performed to examine the structural, chemical, and mechanical properties of the inkjetted hydrogel material. Scanning electron micrographs revealed that the inkjetted material exhibited randomly oriented cross-linked networks. Fourier transform infrared spectroscopy revealed that the piezoelectric inkjet technology technique did not alter chemical bonding in the material. Piezoelectric inkjet printing of medical hydrogels may improve wound repair in next generation eye surgery, fracture fixation, and wound closure devices.}, number={1}, journal={The Journal of Adhesion}, publisher={Informa UK Limited}, author={Doraiswamy, Anand and Crombez, Rene and Shen, Weidian and Lee, Yuan-Shin and Narayan, Roger J.}, year={2010}, month={Jan}, pages={62–71} }
 @article{wei_nori_jin_narayan_narayan_ponarin_smirnov_2010, title={Mott transition in Ga-doped MgxZn1-xO: A direct observation}, volume={171}, ISSN={["1873-4944"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77953133966&partnerID=MN8TOARS}, DOI={10.1016/j.mseb.2010.03.078}, abstractNote={This paper reports the direct evidence for Mott transition in Ga-doped MgxZn1−xO thin films. Highly transparent Ga-doped MgxZn1−xO thin films were grown on c-plane sapphire substrates using pulsed laser deposition. 0.1 at.%, 0.5 at.% and 1 at.% Ga-doped Mg0.1Zn0.9O films were selected for resistivity measurements in the temperature range from 250 K to 40 mK. The 0.1 at.% Ga-doped Mg0.1Zn0.9O thin film showed typical insulator-like behavior and the 1 at.% Ga-doped Mg0.1Zn0.9O thin film showed typical metal-like behavior. The 0.5 at.% Ga-doped Mg0.1Zn0.9O film showed increasing resistivity with decreasing temperature; resistivity was saturated with a value of 1.15 × 10−2 Ω cm at 40 mK, which is characteristic of the metal–insulator transition region. Temperature-dependent conductivity σ(T) in the low temperature range revealed that the electron-electron scattering is the dominant dephasing mechanism. The inelastic scattering time is found to vary as T−3/2.}, number={1-3}, journal={MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS}, publisher={Elsevier BV}, author={Wei, Wei and Nori, Sudhakar and Jin, Chunming and Narayan, Jagdish and Narayan, Roger J. and Ponarin, Dmtri and Smirnov, Alex}, year={2010}, month={Jul}, pages={90–92} }
 @article{wei_jin_narayan_narayan_2010, title={Optical and electrical properties of gallium-doped MgxZn1−xO}, volume={107}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.3271415}, DOI={10.1063/1.3271415}, abstractNote={In this study, the optical and electrical properties of epitaxial single crystal gallium-doped MgxZn1−xO thin films grown on c-plane sapphire substrates by pulsed laser deposition were investigated. In these films, the Ga content was varied from 0.05 to 7 at. % and the Mg content was varied from 5 to 15 at. %. X-ray diffraction showed that the solid solubility limit of Ga in MgxZn1−xO is less than 3 at. %. The absorption spectra were fitted to examine Ga doping effects on bandgap and band tail characteristics. Distinctive trends in fitted bandgap and band tail characteristics were determined in films with Ga content below 3 at. % and Ga content above 3 at. %. The effects of bandgap engineering on optical transparency were evaluated using transmission spectra. Carrier concentration and Hall mobility data were obtained as functions of Ga content and Mg content. The electrical properties were significantly degraded when the Ga content exceeded 3 at. %. Correlations between conduction mechanisms and gallium doping of MgxZn1−xO thin films were described. In addition, the effect of bandgap engineering on the electrical properties of epitaxial single crystal gallium-doped MgxZn1−xO thin films was discussed.}, number={1}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Wei, Wei and Jin, Chunming and Narayan, Jagdish and Narayan, Roger J.}, year={2010}, month={Jan}, pages={013510} }
 @article{boehm_gittard_byrne_doraiswamy_wilker_dunaway_crombez_shen_lee_narayan_2010, title={Piezoelectric inkjet printing of medical adhesives and sealants}, volume={62}, ISSN={1047-4838 1543-1851}, url={http://dx.doi.org/10.1007/S11837-010-0109-4}, DOI={10.1007/S11837-010-0109-4}, number={7}, journal={JOM}, publisher={Springer Science and Business Media LLC}, author={Boehm, Ryan D. and Gittard, Shaun D. and Byrne, Jacqueline M. H. and Doraiswamy, Anand and Wilker, Jonathan J. and Dunaway, Timothy M. and Crombez, Rene and Shen, Weidian and Lee, Yuan-Shin and Narayan, Roger J.}, year={2010}, month={Jul}, pages={56–60} }
 @article{narayan_roeder_2010, title={Recent Advances in Biological Materials Science and Biomedical Materials}, volume={62}, ISSN={["1047-4838"]}, DOI={10.1007/s11837-010-0106-7}, number={7}, journal={JOM}, author={Narayan, Roger J. and Roeder, Ryan K.}, year={2010}, month={Jul}, pages={38–38} }
 @article{yang_jin_zhou_narayan_narayan_2010, title={Role of twin boundaries in semiconductor to metal transition characteristics of VO2 films}, volume={97}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.3481075}, DOI={10.1063/1.3481075}, abstractNote={Epitaxial (002) VO2 films were grown on c-sapphire with Ga:ZnO and ZnO buffer layers. We investigated the influence of twin boundaries on the semiconductor-to-metal transition (SMT) characteristics of VO2, when current flows parallel and perpendicular to the twin boundaries. The structure of the twin boundary was kept the same for these two configurations. The hysteresis in SMT characteristics is considerably reduced when current flows parallel to the boundaries compared to that in the normal direction of the boundaries. We present a model to explain these observations and discuss the role of these boundaries on the SMT characteristics, and the importance of grain boundary engineering in the design of VO2 based devices.}, number={7}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Yang, Tsung-Han and Jin, Chunming and Zhou, Honghui and Narayan, Roger J. and Narayan, J.}, year={2010}, month={Aug}, pages={072101} }
 @article{yang_aggarwal_gupta_zhou_narayan_narayan_2010, title={Semiconductor-metal transition characteristics of VO2 thin films grown on c- and r-sapphire substrates}, volume={107}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.3327241}, DOI={10.1063/1.3327241}, abstractNote={We have made a comparative study of epitaxial growth of VO2 thin films on c-cut (0001) and r-cut (11¯02) sapphire substrates, and the semiconductor to metal transition (SMT) characteristics of these films have been correlated with their structural details. On c-sapphire, VO2 grows epitaxially in (002) orientation. These (002) oriented VO2 films have 60° twin boundaries due to three equivalent in-plane orientations. The epitaxial VO2 films on r-sapphire consisted of two orientations, namely (200) and (2¯11). The coexistence of these two orientations of VO2 has been explained on the basis of similarity of atomic arrangements in (200) and (2¯11) planes. The thermal hysteresis (ΔH), sharpness of the transition (ΔT), and the transition temperature for VO2 films on c-sapphire were found to be 4.8, 8.5, and 72.6 °C, respectively, which were higher than the corresponding values of 3.3, 5.4, and 60.3 °C for films on r-sapphire. The SMT temperature for VO2 films on c-sapphire was close to the bulk value of 68.0 °C. The significant decrease in transition temperature to 60.3 °C for VO2 films on r-sapphire has been attributed to the compressive strain along [002] direction of VO2.}, number={5}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Yang, Tsung-Han and Aggarwal, Ravi and Gupta, Alok and Zhou, Honghui and Narayan, Roger J. and Narayan, J.}, year={2010}, month={Mar}, pages={053514} }
 @article{aggarwal_zhou_jin_narayan_narayan_2010, title={Semipolar r-plane ZnO films on Si(100) substrates: Thin film epitaxy and optical properties}, volume={107}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.3406260}, DOI={10.1063/1.3406260}, abstractNote={We report heteroepitaxial growth of (101¯2) oriented (r-plane) ZnO films on Si(100) substrates. The films were grown by pulsed laser deposition and integration of ZnO with silicon was achieved using a tetragonal yttria stabilized zirconia (YSZ) buffer layer. It was observed that ZnO films grown at temperatures in the range of 700–750 °C with relatively high oxygen pressure (∼70 mTorr) were (101¯2) oriented. ZnO films deposited with lower oxygen pressures were found to be purely (0002) orientated. Experiments carried out to elucidate the role of oxygen pressure indicated that the crystallographic orientation of ZnO depends on the nature of atomic termination of YSZ layer. It has been proposed that crystallographic orientation of ZnO is controlled by chemical free energy associated with ZnO-YSZ interface. Detailed x-ray diffraction and transmission electron microscopy studies showed existence of four types of in-plane domains in r-plane ZnO films. Optical characterization demonstrated that photoluminescence of r-plane ZnO films was superior to that of c-plane ZnO films grown under similar conditions.}, number={11}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Aggarwal, Ravi and Zhou, Honghui and Jin, Chunming and Narayan, J. and Narayan, Roger J.}, year={2010}, month={Jun}, pages={113530} }
 @article{gittard_pierson_ha_wu_narayan_robinson_2010, title={Supercapacitive transport of pharmacologic agents using nanoporous gold electrodes}, volume={5}, ISSN={["1860-7314"]}, DOI={10.1002/biot.200900250}, abstractNote={AbstractIn this study, nanoporous gold supercapacitors were produced by electrochemical dealloying of gold‐silver alloy. Scanning electron microscopy and energy dispersive X‐ray spectroscopy confirmed completion of the dealloying process and generation of a porous gold material with ∼10 nm diameter pores. Cyclic voltammetry and chronoamperometry of the nanoporous gold electrodes indicated that these materials exhibited supercapacitor behavior. The storage capacity of the electrodes measured by chronoamperometry was ∼3 mC at 200 mV. Electrochemical storage and voltage‐controlled delivery of two model pharmacologic agents, benzylammonium and salicylic acid, was demonstrated. These results suggest that capacitance‐based storage and delivery of pharmacologic agents may serve as an alternative to conventional drug delivery methods.}, number={2}, journal={BIOTECHNOLOGY JOURNAL}, author={Gittard, Shaun D. and Pierson, Bonnie E. and Ha, Cindy M. and Wu, Chung-An Max and Narayan, Roger J. and Robinson, David B.}, year={2010}, month={Feb}, pages={192–200} }
 @article{narayan_2010, title={The next generation of biomaterial development PREFACE}, volume={368}, ISSN={["1471-2962"]}, DOI={10.1098/rsta.2010.0001}, abstractNote={As defined by [Park & Lakes (2007)][1], a biomaterial is a material that replaces either a tissue within the body or a function of the body. The development of novel biomaterials is an iterative process that involves the creation of increasingly safer, more reliable, more inexpensive and more}, number={1917}, journal={PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES}, author={Narayan, Roger J.}, year={2010}, month={Apr}, pages={1831–1837} }
 @article{narayan_2010, title={Titania: a material-based approach to oil spill remediation?}, volume={13}, ISSN={1369-7021}, url={http://dx.doi.org/10.1016/S1369-7021(10)70166-8}, DOI={10.1016/S1369-7021(10)70166-8}, abstractNote={The anatase phase of titania is being considered for use in oil spill remediation due to its high photocatalytic efficiency and its activity under a wide range of environmental conditions.}, number={9}, journal={Materials Today}, publisher={Elsevier BV}, author={Narayan, Roger}, year={2010}, month={Sep}, pages={58–59} }
 @article{gittard_ovsianikov_akar_chichkov_monteiro-riviere_stafslien_chisholm_shin_shih_lin_et al._2010, title={Two Photon Polymerization-Micromolding of Polyethylene Glycol-Gentamicin Sulfate Microneedles}, volume={12}, ISSN={["1438-1656"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000277655500011&KeyUID=WOS:000277655500011}, DOI={10.1002/adem.200980012}, abstractNote={AbstractThe use of microneedles for transdermal drug delivery is limited due to the risk of infection associated with formation of channels through the stratum corneum layer of the epidermis. The risk of infection associated with use of microneedles may be reduced by imparting these devices with antimicrobial properties. In this study, a photopolymerization‐micromolding technique was used to fabricate microneedle arrays from a photosensitive material containing polyethylene glycol 600 diacrylate, gentamicin sulfate, and a photoinitiator. Scanning electron microscopy indicated that the photopolymerization‐micromolding process produced microneedle arrays that exhibited good microneedle‐to‐microneedle uniformity. An agar plating assay revealed that microneedles fabricated with polyethylene glycol 600 diacrylate containing 2 mg mL−1 gentamicin sulfate inhibited growth of Staphylococcus aureus bacteria. Scanning electron microscopy revealed no platelet aggregation on the surfaces of platelet rich plasma‐exposed undoped polyethylene glycol 600 diacrylate microneedles and gentamicin‐doped polyethylene glycol 600 diacrylate microneedles. These efforts will enable wider adoption of microneedles for transdermal delivery of pharmacologic agents.}, number={4}, journal={ADVANCED ENGINEERING MATERIALS}, author={Gittard, Shaun D. and Ovsianikov, Aleksandr and Akar, Hasan and Chichkov, Boris and Monteiro-Riviere, Nancy A. and Stafslien, Shane and Chisholm, Bret and Shin, Chun-Che and Shih, Chun-Ming and Lin, Shing-Jong and et al.}, year={2010}, month={Apr}, pages={B77–B82} }
 @article{narayan_2010, title={Use of nanomaterials in water purification}, volume={13}, ISSN={1369-7021}, url={http://dx.doi.org/10.1016/S1369-7021(10)70108-5}, DOI={10.1016/S1369-7021(10)70108-5}, abstractNote={The recent earthquake in Haiti has focused worldwide attention on the need for improved water purification materials and systems. Numerous individuals, religious charities, non-governmental organizations, and private companies have sent water purifications systems to Haiti in recent months in order to stem the spread of waterborne diseases. This recent tragedy has placed a spotlight on the ongoing problem of inadequate access to safe water in developing countries. The United Nations estimates that 1.1 billion people, or eighteen per cent of the world population, cannot obtain safe water at this time1. In developing countries, waterborne diseases such as cholera, dysentery, enteric fever, and hepatitis A are quite common2. Endemic diarrheal diseases place individuals, particularly children, at risk of arrested growth, malnutrition, and neurological conditions. The World Health Organization states that 1.6 million individuals, mostly young children, die from diarrheal diseases each year1.}, number={6}, journal={Materials Today}, publisher={Elsevier BV}, author={Narayan, Roger}, year={2010}, month={Jun}, pages={44–46} }
 @article{gittard_hojo_hyde_scarel_narayan_parsons_2009, title={Antifungal Textiles Formed Using Silver Deposition in Supercritical Carbon Dioxide}, volume={19}, ISSN={1059-9495 1544-1024}, url={http://dx.doi.org/10.1007/s11665-009-9514-7}, DOI={10.1007/s11665-009-9514-7}, number={3}, journal={Journal of Materials Engineering and Performance}, publisher={Springer Science and Business Media LLC}, author={Gittard, Shaun D. and Hojo, Daisuke and Hyde, G. Kevin and Scarel, Giovanna and Narayan, Roger J. and Parsons, Gregory N.}, year={2009}, month={Jul}, pages={368–373} }
 @article{gittard_perfect_monteiro-riviere_wei_jin_narayan_2009, title={Assessing the antimicrobial activity of zinc oxide thin films using disk diffusion and biofilm reactor}, volume={255}, ISSN={["1873-5584"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000263893800027&KeyUID=WOS:000263893800027}, DOI={10.1016/j.apsusc.2009.01.009}, abstractNote={The electronic and chemical properties of semiconductor materials may be useful in preventing growth of microorganisms. In this article, in vitro methods for assessing microbial growth on semiconductor materials will be presented. The structural and biological properties of silicon wafers coated with zinc oxide thin films were evaluated using atomic force microscopy, X-ray photoelectron spectroscopy, and MTT viability assay. The antimicrobial properties of zinc oxide thin films were established using disk diffusion and CDC Biofilm Reactor studies. Our results suggest that zinc oxide and other semiconductor materials may play a leading role in providing antimicrobial functionality to the next-generation medical devices.}, number={11}, journal={APPLIED SURFACE SCIENCE}, author={Gittard, Shaun D. and Perfect, John R. and Monteiro-Riviere, Nancy A. and Wei, Wei and Jin, Chunming and Narayan, Roger J.}, year={2009}, month={Mar}, pages={5806–5811} }
 @article{narayan_monteiro-riviere_brigmon_pellin_elam_2009, title={Atomic layer deposition of TiO2 thin films on nanoporous alumina templates: Medical applications}, volume={61}, ISSN={["1543-1851"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000266911200002&KeyUID=WOS:000266911200002}, DOI={10.1007/s11837-009-0081-z}, number={6}, journal={JOM}, author={Narayan, Roger J. and Monteiro-Riviere, Nancy A. and Brigmon, Robin L. and Pellin, Michael J. and Elam, Jeffrey W.}, year={2009}, month={Jun}, pages={12–16} }
 @article{cristescu_popescu_popescu_grigorescu_mihailescu_mihaiescu_gittard_narayan_buruiana_stamatin_et al._2009, title={Functional polyethylene glycol derivatives nanostructured thin films synthesized by matrix-assisted pulsed laser evaporation}, volume={255}, ISSN={0169-4332}, url={http://dx.doi.org/10.1016/j.apsusc.2009.04.110}, DOI={10.1016/j.apsusc.2009.04.110}, abstractNote={Abstract We report the thin film deposition by matrix-assisted pulsed laser evaporation (MAPLE) of a polymer conjugate with an hydrophilic sequence between metronidazole molecules that was covalently attached to both oligomer ends of carboxylate poly(ethylene glycol) (PEG 1.5–metronidazole). A pulsed KrF* excimer laser was used to deposit the drug–polymer composite films. Fourier transform infrared spectroscopy was used to demonstrate that MAPLE-transferred materials exhibited chemical properties similar to the starting materials. The dependence of the surface morphology on incident laser fluence is given.}, number={24}, journal={Applied Surface Science}, publisher={Elsevier BV}, author={Cristescu, R. and Popescu, C. and Popescu, A. and Grigorescu, S. and Mihailescu, I.N. and Mihaiescu, D. and Gittard, S.D. and Narayan, R.J. and Buruiana, T. and Stamatin, I. and et al.}, year={2009}, month={Sep}, pages={9873–9876} }
 @article{miller_aggarwal_doraiswamy_lin_lee_narayan_2009, title={Laser micromachining for biomedical applications}, volume={61}, ISSN={["1047-4838"]}, DOI={10.1007/s11837-009-0130-7}, number={9}, journal={JOM}, author={Miller, Philip R. and Aggarwal, Ravi and Doraiswamy, Anand and Lin, Yi Jen and Lee, Yuan-Shin and Narayan, Roger J.}, year={2009}, month={Sep}, pages={35–40} }
 @article{aggarwal_nori_jin_pant_trichy_kumar_narayan_narayan_2009, title={Magnetic properties and their dependence on deposition parameters of Co/Al2O3 multilayers grown by pulsed laser deposition}, volume={57}, ISSN={["1359-6454"]}, DOI={10.1016/j.actamat.2009.01.018}, abstractNote={Co/Al2O3 multilayered thin films were grown on Si (111) substrates by pulsed laser deposition (PLD) at temperatures from room temperature (RT) to 600 °C. The Co/Al2O3 multilayered thin film grown at RT contains continuous cobalt layers in alumina matrices, with no evidence of island formation. On the other hand, cobalt showed a tendency to form islands in alumina matrices for growth temperatures in the range of 300–600 °C. All the Co/Al2O3 multilayered thin films showed ferromagnetic behavior up to RT. It was observed that variations in the deposition parameters can significantly influence the magnetic properties of Co/Al2O3 multilayers. Depending on the temperature and pulse rate, RT coercivities in the 50–300 Oe range were observed. Films deposited at 600 °C using a laser pulse rate of 10 Hz exhibited a decrease of coercivity with increasing measurement temperature. On the other hand, films deposited at 600 °C using a reduced pulse rate of 2 Hz demonstrated an "anomalous" relationship between low-temperature coercivity and temperature. In these films, coercivity exhibited a weak tendency to increase with temperature. Squareness (Mr/Ms) of the hysteresis loops and its dependence on the temperature was also shown to be strongly affected by the deposition parameters. These observations have been rationalized on the basis of two competing magnetic anisotropies that act along different directions in the material.}, number={6}, journal={ACTA MATERIALIA}, author={Aggarwal, Ravi and Nori, Sudhakar and Jin, Chunming and Pant, Punam and Trichy, Gopinath R. and Kumar, Dhananjay and Narayan, J. and Narayan, Roger J.}, year={2009}, month={Apr}, pages={2040–2046} }
 @article{adiga_jin_curtiss_monteiro-riviere_narayan_2009, title={Nanoporous membranes for medical and biological applications}, volume={1}, ISSN={1939-5116}, url={http://dx.doi.org/10.1002/wnan.50}, DOI={10.1002/wnan.50}, abstractNote={AbstractSynthetic nanoporous materials have numerous potential biological and medical applications that involve sorting, sensing, isolating, and releasing biological molecules. Nanoporous systems engineered to mimic natural filtration systems are actively being developed for use in smart implantable drug delivery systems, bioartificial organs, and other novel nano‐enabled medical devices. Recent advances in nanoscience have made it possible to precisely control the morphology as well as physical and chemical properties of the pores in nanoporous materials that make them increasingly attractive for regulating and sensing transport at the molecular level. In this work, an overview of nanoporous membranes for biomedical applications is given. Various in vivo and in vitro membrane applications, including biosensing, biosorting, immunoisolation, and drug delivery, are presented. Different types of nanoporous materials and their fabrication techniques are discussed with an emphasis on membranes with ordered pores. Desirable properties of membranes used in implantable devices, including biocompatibility and antibiofouling behavior, are discussed. The use of surface modification techniques to improve the function of nanoporous membranes is reviewed. Despite the extensive research carried out in fabrication, characterization, and modeling of nanoporous materials, there are still several challenges that must be overcome in order to create synthetic nanoporous systems that behave similarly to their biological counterparts. Copyright © 2009 John Wiley & Sons, Inc.This article is categorized under:

Implantable Materials and Surgical Technologies > Nanomaterials and Implants
}, number={5}, journal={Wiley Interdisciplinary Reviews: Nanomedicine and Nanobiotechnology}, publisher={Wiley}, author={Adiga, Shashishekar P. and Jin, Chunmin and Curtiss, Larry A. and Monteiro-Riviere, Nancy A. and Narayan, Roger J.}, year={2009}, month={Jul}, pages={568–581} }
 @article{wei_jin_narayan_narayan_2009, title={Optical and electrical properties of bandgap engineered gallium-doped MgxZn1-xO films}, volume={149}, ISSN={["1879-2766"]}, DOI={10.1016/j.ssc.2009.06.021}, abstractNote={In this study, the optical and electrical properties of heavily gallium-doped MgxZn1−xO films were investigated. Films were epitaxially grown on c-plane sapphire substrates using pulsed laser deposition. Film transparency was shown to be greater than 90% in the visible spectrum. Absorption was shown to be extended to lower wavelengths in films with higher magnesium concentration values. Although transparency in the ultraviolet wavelength range was improved, conductivity was decreased. In MgxZn1−xO films with 0.5 at.% gallium, resistivity was increased from 1.9×10−3Ωcm to 3.62×10−2Ωcm as the magnesium concentration was increased from five atomic percent to fifteen atomic percent. These efforts will facilitate the development of zinc oxide-based ultraviolet–blue light emitting diodes, ultraviolet–blue light laser diodes, and other optoelectronic devices.}, number={39-40}, journal={SOLID STATE COMMUNICATIONS}, author={Wei, Wei and Jin, Chunming and Narayan, Jagdish and Narayan, Roger J.}, year={2009}, month={Oct}, pages={1670–1673} }
 @article{stewart_pierson_aggarwal_narayan_2009, title={Piezoelectric inkjet printing of a cross-hatch immunoassay on a disposable nylon membrane}, volume={4}, ISSN={1860-6768}, url={http://dx.doi.org/10.1002/biot.200800234}, DOI={10.1002/biot.200800234}, abstractNote={AbstractThe development of a cost‐effective method for manufacturing immunoassays is a key step towards their commercial use. In this study, a piezoelectric inkjet printer and a nylon membrane were used to fabricate a disposable immunoassay. Using a piezoelectric inkjet printer, a cross‐hatch pattern of goat anti‐mouse antibody (GαM) and rabbit anti‐horseradish peroxidase (RαHRP) antibody were deposited on the nylon membrane. These patterns were subsequently treated with a solution containing rabbit anti‐goat antibody labeled with horseradish peroxidase (RαG‐HRP). The effectiveness of the immobilization process was examined using tetramethylbenzidine (TMB), which oxidizes in the presence of HRP to form a visible precipitate. Optical evaluation of the TMB precipitate was used to assess the precision of the features in the inkjet‐printed pattern as well as antibody functionality following inkjet printing. Uniform patterns that contained functional antibodies were fabricated using the piezoelectric inkjet printer. These results suggest that piezoelectric inkjet printing may be used to fabricate low‐cost disposable immunoassays for biotechnology and healthcare applications.}, number={2}, journal={Biotechnology Journal}, publisher={Wiley}, author={Stewart, Thomas N. and Pierson, Bonnie E. and Aggarwal, Ravi and Narayan, Roger J.}, year={2009}, month={Feb}, pages={206–209} }
 @article{gittard_narayan_jin_ovsianikov_chichkov_monteiro-riviere_stafslien_chisholm_2009, title={Pulsed laser deposition of antimicrobial silver coating on Ormocer (R) microneedles}, volume={1}, ISSN={["1758-5090"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000278118300001&KeyUID=WOS:000278118300001}, DOI={10.1088/1758-5082/1/4/041001}, abstractNote={One promising option for transdermal delivery of protein- and nucleic acid-based pharmacologic agents involves the use of microneedles. However, microneedle-generated pores may allow microorganisms to penetrate the stratum corneum layer of the epidermis and cause local or systemic infection. In this study, microneedles with antimicrobial functionality were fabricated using two-photon polymerization–micromolding and pulsed laser deposition. The antibacterial activity of the silver-coated organically modified ceramic (Ormocer®) microneedles was demonstrated using an agar diffusion assay. Human epidermal keratinocyte viability on the Ormocer® surfaces coated with silver was similar to that on uncoated Ormocer® surfaces. This study indicates that coating microneedles with silver thin films using pulsed laser deposition is a useful and novel approach for creating microneedles with antimicrobial functionality.}, number={4}, journal={BIOFABRICATION}, author={Gittard, S. D. and Narayan, R. J. and Jin, C. and Ovsianikov, A. and Chichkov, B. N. and Monteiro-Riviere, N. A. and Stafslien, S. and Chisholm, B.}, year={2009}, month={Dec} }
 @article{gittard_narayan_lusk_morel_stockmans_ramsey_laverde_phillips_monteiro-riviere_ovsianikov_et al._2009, title={Rapid prototyping of scaphoid and lunate bones}, volume={4}, ISSN={1860-6768 1860-7314}, url={http://dx.doi.org/10.1002/biot.200800233}, DOI={10.1002/biot.200800233}, abstractNote={AbstractIn this study, a novel rapid prototyping technology was used to fabricate scaphoid and lunate bone prostheses, two carpal bones that are prone to avascular necrosis. Carpal prostheses were fabricated with an Envisiontec Perfactory® SXGA stereolithography system using Envisiontec eShell 200 photocurable polymer. Fabrication was guided using 3‐D models, which were generated using Mimics software (Materialise NV, Leuven, Belgium) from patient computer tomography data. The prostheses were fabricated in a layer‐by‐layer manner; ∼ 50‐μm thick layers were observed in the prostheses. Hardness and Young's modulus values of polymerized eShell 200 material were 93.8 ± 7.25 MPa and 3050 ± 90 MPa, respectively. The minimum compressive force required for fracture was 1360 N for the scaphoid prosthesis and 1248 N for the lunate prosthesis. Polymerized Envisiontec eShell material exhibited high human neonatal epidermal keratinocyte cell viability rate in an MTT assay. The results of this study indicate that small bone prostheses fabricated by stereolithography using eShell 200 polymer may have suitable geometry, mechanical properties, and cytocompatibility properties for in vivo use.}, number={1}, journal={Biotechnology Journal}, publisher={Wiley}, author={Gittard, Shaun D. and Narayan, Roger and Lusk, Jason and Morel, Pierre and Stockmans, Filip and Ramsey, Michael and Laverde, Claire and Phillips, Jack and Monteiro-Riviere, Nancy A. and Ovsianikov, Aleksandr and et al.}, year={2009}, month={Jan}, pages={129–134} }
 @article{gupta_aggarwal_gupta_dutta_narayan_narayan_2009, title={Semiconductor to metal transition characteristics of VO2 thin films grown epitaxially on Si (001)}, volume={95}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.3232241}, DOI={10.1063/1.3232241}, abstractNote={We report semiconductor to metal transition (SMT) characteristics of vanadium dioxide (VO2) grown epitaxially on Si (001) at 500 °C. The epitaxial integration with Si (001) was achieved by using epitaxial tetragonal yttria-stabilized zirconia (YSZ) as an intermediate buffer layer, which was grown in situ. From x-ray (θ-2θ and ϕ-scan) and electron diffraction studies, we established that VO2 and YSZ grow in (020) and (001) orientations, respectively, on Si (001) substrate and epitaxial relationship was established to be “VO2[001] or VO2[100]”//YSZ[110]//Si [100] and VO2(010)//YSZ(001)//Si(001). VO2/YSZ/Si(001) heterostructures showed approximately three orders of magnitude reversible change in resistivity and hysteresis of ∼6 K upon traversing the transition temperature. A 10 °C increase in the SMT temperature of these VO2 films, compared to the value reported for bulk VO2, has been explained on the basis of uniaxial stress along the c-axis, which can stabilize the covalent monoclinic phase up to higher temperatures. A correlation between in-plane orientations of the film and the transition width has also been suggested, which is consistent with our previously published thermodynamic model.}, number={11}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Gupta, A. and Aggarwal, R. and Gupta, P. and Dutta, T. and Narayan, Roger J. and Narayan, J.}, year={2009}, month={Sep}, pages={111915} }
 @article{narayan_2009, title={Smarter implants: nanomedicine}, volume={12}, ISSN={1369-7021}, url={http://dx.doi.org/10.1016/S1369-7021(09)70103-8}, DOI={10.1016/S1369-7021(09)70103-8}, number={4}, journal={Materials Today}, publisher={Elsevier BV}, author={Narayan, Roger}, year={2009}, month={Apr}, pages={10} }
 @article{boehm_narayan_aggarwal_monteiro-riviere_lacour_2009, title={Stretchable diamond-like carbon microstructures for biomedical applications}, volume={61}, ISSN={["1543-1851"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000269953700010&KeyUID=WOS:000269953700010}, DOI={10.1007/s11837-009-0134-3}, number={9}, journal={JOM}, author={Boehm, Ryan and Narayan, Roger J. and Aggarwal, Ravi and Monteiro-Riviere, Nancy A. and Lacour, Stephanie P.}, year={2009}, month={Sep}, pages={53–58} }
 @article{pant_budai_aggarwal_narayan_narayan_2009, title={Structural characterization of two-step growth of epitaxial ZnO films on sapphire substrates at low temperatures}, volume={42}, ISSN={0022-3727 1361-6463}, url={http://dx.doi.org/10.1088/0022-3727/42/10/105409}, DOI={10.1088/0022-3727/42/10/105409}, abstractNote={We have investigated two-step growth of high-quality epitaxial ZnO films, where the first layer—the buffer layer (nucleation layer template)—is grown at a low temperature (230–290 °C) to induce a smooth (two-dimensional) growth. This is followed by growth at a moderate temperature ∼430 °C to form high-quality smooth ZnO layers for device structures. It was possible to reduce the growth temperature to 250–290 °C and obtain a smooth epitaxial template layer on sapphire (0 0 0 1) substrates with surface roughness less than 1 nm. After the high-temperature growth, the film surface undulations (roughness) increased to about 2 nm, but it is still quite smooth. The calculation of c and a lattice parameters by high-resolution x-ray diffraction shows that the a lattice parameter is fully relaxed at the growth temperatures but the c lattice parameter is dependent on the defect concentration in the growing film. A decoupling between a and c lattice parameters of the films is observed, which leads to abnormal Poisson's ratios ranging from 0.08 to 0.54. The decoupling of the lattice parameters is analysed based on growth characteristics and the presence of strain and defects in the grown films. We present our detailed studies on the nature of epitaxy, defects and interfaces by using comprehensive x-ray diffraction and high-resolution TEM studies.}, number={10}, journal={Journal of Physics D: Applied Physics}, publisher={IOP Publishing}, author={Pant, P and Budai, J D and Aggarwal, R and Narayan, R J and Narayan, J}, year={2009}, month={Apr}, pages={105409} }
 @article{narayan_roeder_2009, title={The development of novel materials for medical devices}, volume={61}, ISSN={1047-4838 1543-1851}, url={http://dx.doi.org/10.1007/s11837-009-0125-4}, DOI={10.1007/s11837-009-0125-4}, abstractNote={Healthcare consumers continue to demand ever more complex devices for diagnosis and treatment of medical conditions. The development of novel medical devices was traditionally left to surgeon-scientists, who encountered patient suffering and developed medical devices using materials that were available in their local communities and that seemed to exhibit properties suitable for the desired function. Today, the medical device industry increasingly relies on knowledge of materials science and engineering to develop sophisticated replacements for natural tissues. For example, the $3.2 billion cardiac stent market has expanded over the past decade due to the development of fl exible polymer balloon catheters that expand obstructed blood vessels; metallic wire meshes that provide structural support to blood vessels; and biodegradable polymers that release antiproliferative pharmacologic agents in order to minimize closure (restenosis) of blood vessels. The medical device industry accounts for nearly $100 billion in revenues, and is expected to increase over the coming decades. Signifi cant strides are being made in the development of novel materials for use in medical devices. Advances in medical devices and prostheses were made during and after World War II. Biologically inert metals, ceramics, The Development of Novel Materials for Medical Devices}, number={9}, journal={JOM}, publisher={Springer Science and Business Media LLC}, author={Narayan, Roger J. and Roeder, Ryan K.}, year={2009}, month={Sep}, pages={13–13} }
 @article{pant_budai_aggarwal_narayan_narayan_2009, title={Thin film epitaxy and structure property correlations for non-polar ZnO films}, volume={57}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2009.05.031}, abstractNote={Heteroepitaxial growth and strain relaxation were investigated in non-polar a-plane (1 1 −2 0)ZnO films grown on r-plane (1 0 −1 2)sapphire substrates in the temperature range 200–700 °C by pulsed laser deposition. The lattice misfit in the plane of the film for this orientation varied from −1.26% in [0 0 0 1] to −18.52% in the [−1 1 0 0] direction. The alignment of (1 1 −2 0)ZnO planes parallel to (1 0 −1 2)sapphire planes was confirmed by X-ray diffraction θ−2θ scans over the entire temperature range. X-ray ϕ-scans revealed the epitaxial relationship:[0 0 0 1]ZnO‖[−1 1 0 1]sap; [–1 1 0 0]ZnO‖[−1 −1 2 0]sap. Depending on the growth temperature, variations in the structural, optical and electrical properties were observed in the grown films. Room temperature photoluminescence for films grown at 700 °C shows a strong band-edge emission. The ratio of the band-edge emission to green band emission is 135:1, indicating reduced defects and excellent optical quality of the films. The resistivity data for the films grown at 700 °C shows semiconducting behavior with room temperature resistivity of 2.2 × 10−3 Ω-cm.}, number={15}, journal={ACTA MATERIALIA}, author={Pant, P. and Budai, J. D. and Aggarwal, R. and Narayan, Roger J. and Narayan, J.}, year={2009}, month={Sep}, pages={4426–4431} }
 @article{cristescu_mihailescu_stamatin_doraiswamy_narayan_westwood_wilker_stafslien_chisholm_chrisey_2009, title={Thin films of polymer mimics of cross-linking mussel adhesive proteins deposited by matrix assisted pulsed laser evaporation}, volume={255}, ISSN={0169-4332}, url={http://dx.doi.org/10.1016/j.apsusc.2008.11.012}, DOI={10.1016/j.apsusc.2008.11.012}, abstractNote={Mussels secrete specialized adhesives known as mussel adhesive proteins, which allow attachment of the organisms to underwater marine environments. Obtaining large quantities of naturally derived mussel adhesive proteins adhesives has proven to date rather problematic, thus, synthetic analogs of mussel adhesive proteins have recently been developed. We report deposition of 1:100 and 1:1000 poly[(3,4-dihydroxystyrene)-co-styrene)] mussel adhesive protein analogs by matrix assisted pulsed laser evaporation (MAPLE) using an ArF* excimer laser source. The deposited films have been evaluated for their antifouling behavior. The MAPLE-deposited synthetic mussel adhesive protein analog thin films are homogenous and adhesive, making the use of these materials in thin film form a viable option.}, number={10}, journal={Applied Surface Science}, publisher={Elsevier BV}, author={Cristescu, R. and Mihailescu, I.N. and Stamatin, I. and Doraiswamy, A. and Narayan, R.J. and Westwood, G. and Wilker, J.J. and Stafslien, S. and Chisholm, B. and Chrisey, D.B.}, year={2009}, month={Mar}, pages={5496–5498} }
 @article{narayan_bochlert_2008, title={Advanced processing of biomaterials}, volume={28}, ISSN={["0928-4931"]}, DOI={10.1016/j.msec.2007.04.001}, number={3}, journal={MATERIALS SCIENCE & ENGINEERING C-BIOMIMETIC AND SUPRAMOLECULAR SYSTEMS}, author={Narayan, Roger Jagdish and Bochlert, Carl}, year={2008}, month={Apr}, pages={321–322} }
 @article{jin_wei_zhou_yang_narayan_2008, title={Epitaxial growth and Ohmic contacts in MgxZn1-xO/TiN/Si(111) heterostructures}, volume={93}, ISSN={["1077-3118"]}, DOI={10.1063/1.3054347}, abstractNote={In this work, the electronic properties of Mg0.1Zn0.9O∕TiN∕Si(111) heterostructures processed using pulsed laser deposition were examined. X-ray diffraction and transmission electron microscopy studies demonstrated epitaxial growth of the titanium nitride buffer layer and the Mg0.1Zn0.9O thin film. Transmission electron microscopy demonstrated a thin (∼5nm) spinel layer along the magnesium zinc oxide/titanium nitride interface. Current-voltage measurements revealed Ohmic contact behavior through the magnesium zinc oxide/titanium nitride interface. These results suggest that the titanium nitride buffer layer in the MgxZn1−xO∕TiN∕Si(111) heterostructure provides a buffer layer for integrating magnesium zinc oxide thin films with silicon substrates, which both enable epitaxial growth and serve as an Ohmic electrode for the magnesium zinc oxide thin film.}, number={25}, journal={APPLIED PHYSICS LETTERS}, author={Jin, Chunming and Wei, Wei and Zhou, Honghui and Yang, Tsung-Han and Narayan, Roger J.}, year={2008}, month={Dec} }
 @article{narayan_2008, title={Foreword}, volume={28}, ISSN={0928-4931}, url={http://dx.doi.org/10.1016/S0928-4931(07)00262-7}, DOI={10.1016/S0928-4931(07)00262-7}, number={1}, journal={Materials Science and Engineering: C}, publisher={Elsevier BV}, author={Narayan, Roger Jagdish}, year={2008}, month={Jan}, pages={vii} }
 @article{aggarwal_jin_pant_narayan_narayan_2008, title={Growth of biepitaxial zinc oxide thin films on silicon (100) using yttria-stabilized zirconia buffer layer}, volume={93}, ISSN={["0003-6951"]}, DOI={10.1063/1.3050529}, abstractNote={In this work, an approach for integrating zinc oxide thin films with Si(100) substrates using an epitaxial tetragonal yttria-stabilized zirconia buffer layer is reported. Selected area electron diffraction measurements revealed the following epitaxial relationship: [110]YSZ∥[100]Si and (001)YSZ∥(001)Si. X-ray diffraction studies demonstrated that subsequent growth of the zinc oxide thin film on the yttria-stabilized zirconia buffer layer occurred with the following epitaxial relationship: (0002)ZnO∥(001)YSZ. The full width at half maximum value for the (0002) peak of zinc oxide was small (∼0.16°), which indicated good crystalline quality. Transmission electron microscopy revealed that the zinc oxide thin film grew epitaxially on an yttria-stabilized zirconia buffer layer in two different orientations, where one orientation was rotated by 30° from the other. The orientation relationship in this case was [101¯0]ZnO∥[100]YSZ or [21¯1¯0]ZnO∥[100]YSZ and (0002)ZnO∥(001)YSZ. The biepitaxial growth of the zinc oxide thin film has been explained in the framework of domain matching epitaxy. Optical emission measurements showed a strong excitonic emission peak from the zinc oxide thin film at ∼377 nm. Minimal green band emission in the photoluminescence spectrum indicated that the concentration of point defects was low. Integration of epitaxial zinc oxide thin films with Si(100) substrates is an important step toward developing practical applications of zinc oxide in a variety of optoelectronic devices.}, number={25}, journal={Applied Physics Letters}, author={Aggarwal, Ravi and Jin, Chunming and Pant, Punam and Narayan, Jagdish and Narayan, Roger J.}, year={2008}, month={Dec}, pages={251905} }
 @article{wei_jin_narayan_2008, title={Growth-Temperature-Controlled Optical Properties of Textured Mg x Zn1−x O Thin Films}, volume={38}, ISSN={0361-5235 1543-186X}, url={http://dx.doi.org/10.1007/s11664-008-0613-2}, DOI={10.1007/s11664-008-0613-2}, number={4}, journal={Journal of Electronic Materials}, publisher={Springer Science and Business Media LLC}, author={Wei, W. and Jin, C. and Narayan, R.J.}, year={2008}, month={Dec}, pages={613–617} }
 @article{doraiswamy_dunaway_wilker_narayan_2009, title={Inkjet printing of bioadhesives}, volume={89B}, ISSN={1552-4973 1552-4981}, url={http://dx.doi.org/10.1002/jbm.b.31183}, DOI={10.1002/jbm.b.31183}, abstractNote={AbstractOver the past century, synthetic adhesives have largely displaced their natural counterparts in medical applications. However, rising concerns over the environmental and toxicological effects of the solvents, monomers, and additives used in synthetic adhesives have recently led the scientific community to seek natural substitutes. Marine mussel adhesive protein is a formaldehyde‐free natural adhesive that demonstrates excellent adhesion to several classes of materials, including glasses, metals, metal oxides, and polymers. In this study, we have demonstrated computer aided design (CAD) patterning of various biological adhesives using piezoelectric inkjet technology. A MEMS‐based piezoelectric actuator was used to control the flow of the mussel adhesive protein solution through the ink jet nozzles. Fourier transform infrared spectroscopy (FTIR), microscopy, and adhesion studies were performed to examine the chemical, structural, and functional properties of these patterns, respectively. FTIR revealed the piezoelectric inkjet technology technique to be nondestructive. Atomic force microscopy was used to determine the extent of chelation caused by Fe(III). The adhesive strength in these materials was correlated with the extent of chelation by Fe(III). Piezoelectric inkjet printing of naturally‐derived biological adhesives may overcome several problems associated with conventional tissue bonding materials. This technique may significantly improve wound repair in next generation eye repair, fracture fixation, wound closure, and drug delivery devices. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009}, number={1}, journal={Journal of Biomedical Materials Research Part B: Applied Biomaterials}, publisher={Wiley}, author={Doraiswamy, Anand and Dunaway, Timothy M. and Wilker, Jonathan J. and Narayan, Roger J.}, year={2009}, month={Apr}, pages={28–35} }
 @article{narayan_aggarwal_wei_jin_monteiro-riviere_crombez_shen_2008, title={Mechanical and biological properties of nanoporous carbon membranes}, volume={3}, ISSN={["1748-605X"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000258916500020&KeyUID=WOS:000258916500020}, DOI={10.1088/1748-6041/3/3/034107}, abstractNote={Implantable blood glucose sensors have inadequate membrane–tissue interfaces for long term use. Biofouling and inflammation processes restrict biosensor membrane stability. An ideal biosensor membrane material must prevent protein adsorption and exhibit cell compatibility. In addition, a membrane must exhibit high porosity and low thickness in order to allow the biosensor to respond to analyte fluctuations. In this study, the structural, mechanical and biological properties of nanoporous alumina membranes coated with diamond-like carbon thin films were examined using scanning probe microscopy, nanoindentation and MTT viability assay. We anticipate that this novel membrane material could find use in immunoisolation devices, kidney dialysis membranes and other medical devices encountering biocompatibility issues that limit in vivo function.}, number={3}, journal={BIOMEDICAL MATERIALS}, author={Narayan, Roger J. and Aggarwal, Ravi and Wei, Wei and Jin, Chunming and Monteiro-Riviere, Nancy A. and Crombez, Rene and Shen, Weidian}, year={2008}, month={Sep} }
 @article{karakoti_monteiro-riviere_aggarwal_davis_narayan_self_mcginnis_seal_2008, title={Nanoceria as antioxidant: Synthesis and biomedical applications}, volume={60}, ISSN={["1543-1851"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000253852900008&KeyUID=WOS:000253852900008}, DOI={10.1007/s11837-008-0029-8}, abstractNote={The therapeutic application of nanomaterials has been a focus of numerous studies in the past decade. Due to its unique redox properties, cerium oxide (ceria) is finding widespread use in the treatment of medical disorders caused by the reactive oxygen intermediates (ROI). The radical-scavenging role of ceria nanoparticles (nanoceria) have been established, as well as the autocatalytic ability of nanoceria to regenerate under various environmental conditions. The synthesis of nanoceria in biocompatible media has also been reported along with cell viability in order to determine the potential use of nanoceria in biomedical applications.}, number={3}, journal={JOM}, author={Karakoti, A. S. and Monteiro-Riviere, N. A. and Aggarwal, R. and Davis, J. P. and Narayan, R. J. and Self, W. T. and McGinnis, J. and Seal, S.}, year={2008}, month={Mar}, pages={33–37} }
 @article{adiga_curtiss_elam_pellin_shih_shih_lin_su_gittard_zhang_et al._2008, title={Nanoporous materials for biomedical devices}, volume={60}, ISSN={1047-4838 1543-1851}, url={http://dx.doi.org/10.1007/s11837-008-0028-9}, DOI={10.1007/s11837-008-0028-9}, number={3}, journal={JOM}, publisher={Springer Science and Business Media LLC}, author={Adiga, Shashishekar P. and Curtiss, Larry A. and Elam, Jeffrey W. and Pellin, Michael J. and Shih, Chun-Che and Shih, Chun-Ming and Lin, Shing-Jong and Su, Yea-Yang and Gittard, Shaun D. and Zhang, Junping and et al.}, year={2008}, month={Mar}, pages={26–32} }
 @article{jin_nori_wei_aggarwal_kumar_narayan_2008, title={Pulsed Laser Deposition of Nanoporous Cobalt Thin Films}, volume={8}, ISSN={["1533-4899"]}, DOI={10.1166/jnn.2008.483}, abstractNote={Nanoporous cobalt thin films were deposited on anodized aluminum oxide (AAO) membranes at room temperature using pulsed laser deposition. Scanning electron microscopy demonstrated that the nanoporous cobalt thin films retained the monodisperse pore size and high porosity of the anodized
 aluminum oxide substrates. Temperature- and field-dependent magnetic data obtained between 10 K and 350 K showed large hysteresis behavior in these materials. The increase of coercivity values was larger for nanoporous cobalt thin films than for multilayered cobalt/alumina thin films. The
 average diameter of the cobalt nanograins in the nanoporous cobalt thin films was estimated to be ∼5 nm for blocking temperatures near room temperature. These results suggest that pulsed laser deposition may be used to fabricate nanoporous magnetic materials with unusual properties for
 biosensing, drug delivery, data storage, and other technological applications.}, number={11}, journal={JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY}, author={Jin, Chunming and Nori, Sudhakar and Wei, Wei and Aggarwal, Ravi and Kumar, Dhananjay and Narayan, Roger J.}, year={2008}, month={Nov}, pages={6043–6047} }
 @article{harris_doraiswamy_narayan_patz_chrisey_2008, title={Recent progress in CAD/CAM laser direct-writing of biomaterials}, volume={28}, ISSN={0928-4931}, url={http://dx.doi.org/10.1016/j.msec.2007.04.013}, DOI={10.1016/j.msec.2007.04.013}, abstractNote={The matrix-assisted pulsed-laser evaporation direct-write (MAPLE DW) process allows for computer-controlled deposition and machining of mesoscopic voxels of material with a high degree of spatial resolution. This article provides a review of current biomedical research activities that involve patterning of three-dimensional structures using the MAPLE DW process. Recent developments in microfabrication of hydroxyapatite-osteoblast-like cell composites, laser micromachining of differentially adherent substrates, and the influence of processing parameters (e.g., laser energy density and spot size) are discussed. The MAPLE DW process may be used to fabricate free-standing cell-seeded networks with unique geometries for tissue engineering, drug discovery, and other biomedical applications.}, number={3}, journal={Materials Science and Engineering: C}, publisher={Elsevier BV}, author={Harris, M.L. and Doraiswamy, A. and Narayan, R.J. and Patz, T.M. and Chrisey, D.B.}, year={2008}, month={Apr}, pages={359–365} }
 @article{menegazzo_jin_narayan_mizaikoff_2007, title={Compositional and Electrochemical Characterization of Noble Metal−Diamondlike Carbon Nanocomposite Thin Films}, volume={23}, ISSN={0743-7463 1520-5827}, url={http://dx.doi.org/10.1021/la062582p}, DOI={10.1021/la062582p}, abstractNote={A detailed characterization of platinum- and gold-diamondlike carbon (DLC) nanocomposite films deposited onto silicon substrates is presented. A modified pulsed laser deposition (PLD) technique was used to incorporate noble metal nanoclusters into hydrogen-free DLC films. Several analytical techniques, including transmission electron microscopy, atomic force microscopy, Rutherford backscattering spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and nanoindentation testing, were used to investigate these thin films in an effort to determine their physical and electrochemical properties. Rutherford backscattering spectroscopy indicated that the gold- and platinum-DLC films contain metal concentrations between three and 36 atomic percent. Cross-sectional transmission electron microscopy revealed that metal is present as arrays of noble metal islands embedded within the DLC matrix, while atomic force microscopy provided evidence of target splashing. In addition, due to the inclusion of metal, metal-DLC thin films exhibited greater conductivity than their metal-free counterparts. The electrochemical properties were studied using quasi-reversible redox couples and correlated to the metal concentration. Finally, the influence of the layer's composition on the electron-transfer kinetics and the achievable working potential window is discussed. The results discussed herein suggest that metal-DLC thin films grown by pulsed laser deposition present a promising alternative electrode material for electrochemistry.}, number={12}, journal={Langmuir}, publisher={American Chemical Society (ACS)}, author={Menegazzo, Nicola and Jin, Chunming and Narayan, Roger J. and Mizaikoff, Boris}, year={2007}, month={Jun}, pages={6812–6818} }
 @article{blalock_bai_narayan_rabiei_2008, title={Effect of substrate temperature on mechanical properties of calcium phosphate coatings}, volume={85B}, ISSN={["1552-4981"]}, DOI={10.1002/jbm.b.30917}, abstractNote={AbstractThe effect of substrate temperature and processing parameters on mechanical properties of nanoscale calcium phosphate coatings are being studied in order to refine the processing technique for Functionally Graded Hydroxyapatite (FGHA) coatings. Coatings were deposited on titanium substrates with a set substrate temperature of 450, 550, 650, or 750°C in an Ion Beam Assisted Deposition (IBAD) system using a sintered hydroxyapatite (HA) target. Mechanical properties of the coatings deposited with a set substrate temperature such as, bonding/adhesion strength to the substrate, nanohardness, and Young's Modulus as well as coating thickness were evaluated and compared with commercial plasma spray HA coatings. It is concluded that depositing FGHA coatings would better be started at 550–650°C to maintain superior properties of the film at the interface. It can also be concluded that the residual stresses caused by different Coefficient of Thermal Expansions (CTEs) between the substrate and coatings are not the only factor controlling the bonding strength and mechanical properties of these samples. Other parameters such as the nature of the interface layers and their bonding to each other as well as the density and grain structure of the coatings must be taken into consideration for an appropriate evaluation of mechanical properties of calcium phosphate coatings deposited on heated substrate. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008}, number={1}, journal={JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS}, author={Blalock, Travis L. and Bai, Xiao and Narayan, Roger and Rabiei, Afsaneh}, year={2008}, month={Apr}, pages={60–67} }
 @article{jin_zhou_graham_narayan_2007, title={In situ Raman spectroscopy of annealed diamondlike carbon–metal composite films}, volume={253}, ISSN={0169-4332}, url={http://dx.doi.org/10.1016/j.apsusc.2007.01.022}, DOI={10.1016/j.apsusc.2007.01.022}, abstractNote={Diamondlike carbon films and diamondlike carbon–metal composite films may provide increased component reliability, decreased fuel consumption, decreased noise/vibration/harshness (NVH), and decreased lubricant use in next generation automotive components. Raman spectra were obtained for diamondlike carbon, diamondlike carbon–platinum composite films, and diamondlike carbon–gold composite films, which were annealed to a temperature of 523 °C. The Raman spectra for these films were fitted using a two-Gaussian function. The variation of the G-peak position, the D-peak position, and the ID/IG ratio was examined as a function of temperature. The unalloyed diamondlike carbon film demonstrated greater thermal stability than the diamondlike carbon–noble metal composite films. These results suggest that the operating temperatures of the diamondlike carbon-coated automotive components must be kept under careful consideration.}, number={15}, journal={Applied Surface Science}, publisher={Elsevier BV}, author={Jin, C. and Zhou, H. and Graham, S. and Narayan, R.J.}, year={2007}, month={May}, pages={6487–6492} }
 @article{narayan_jin_doraiswamy_mihailescu_jelinek_ovsianikov_chichkov_chrisey_2007, title={Laser Processing of Advanced Bioceramics}, volume={9}, ISSN={1438-1656 1527-2648}, url={http://dx.doi.org/10.1002/adem.200790006}, DOI={10.1002/adem.200790006}, abstractNote={Advanced Engineering MaterialsVolume 9, Issue 1-2 p. 83-83 ErratumFree Access Laser Processing of Advanced Bioceramics This article corrects the following: Laser Processing of Advanced Bioceramics R. J. Narayan, C. Jin, A. Doraiswamy, I. N. Mihailescu, M. Jelinek, A. Ovsianikov, B. Chichkov, D. B. Chrisey, Volume 7Issue 12Advanced Engineering Materials pages: 1083-1098 First Published online: January 13, 2006 R. J. Narayan, R. J. Narayan [email protected] University of North Carolina, Chapel Hill USASearch for more papers by this authorC. Jin, C. Jin University of North Carolina, Chapel Hill USASearch for more papers by this authorA. Doraiswamy, A. Doraiswamy University of North Carolina, Chapel Hill USASearch for more papers by this authorI. N. Mihailescu, I. N. Mihailescu Institute of Atomic Physics, Bucharest, RomaniaSearch for more papers by this authorM. Jelinek, M. Jelinek Institute of Physics ASCR, Prague, Czech RepublicSearch for more papers by this authorA. Ovsianikov, A. Ovsianikov Laserzentrum Hannover, Hannover, GermanySearch for more papers by this authorB. Chichkov, B. Chichkov Laserzentrum Hannover, Hannover, GermanySearch for more papers by this authorD. B. Chrisey, D. B. Chrisey Naval Research Laboratory, Washington, USASearch for more papers by this author R. J. Narayan, R. J. Narayan [email protected] University of North Carolina, Chapel Hill USASearch for more papers by this authorC. Jin, C. Jin University of North Carolina, Chapel Hill USASearch for more papers by this authorA. Doraiswamy, A. Doraiswamy University of North Carolina, Chapel Hill USASearch for more papers by this authorI. N. Mihailescu, I. N. Mihailescu Institute of Atomic Physics, Bucharest, RomaniaSearch for more papers by this authorM. Jelinek, M. Jelinek Institute of Physics ASCR, Prague, Czech RepublicSearch for more papers by this authorA. Ovsianikov, A. Ovsianikov Laserzentrum Hannover, Hannover, GermanySearch for more papers by this authorB. Chichkov, B. Chichkov Laserzentrum Hannover, Hannover, GermanySearch for more papers by this authorD. B. Chrisey, D. B. Chrisey Naval Research Laboratory, Washington, USASearch for more papers by this author First published: 22 March 2007 https://doi.org/10.1002/adem.200790006Citations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume9, Issue1-2February, 2007Pages 83-83 RelatedInformation}, number={1-2}, journal={Advanced Engineering Materials}, publisher={Wiley}, author={Narayan, R. J. and Jin, C. and Doraiswamy, A. and Mihailescu, I. N. and Jelinek, M. and Ovsianikov, A. and Chichkov, B. and Chrisey, D. B.}, year={2007}, month={Feb}, pages={83–83} }
 @article{doraiswamy_narayan_harris_qadri_modi_chrisey_2007, title={Laser microfabrication of hydroxyapatite-osteoblast-like cell composites}, volume={80A}, ISSN={1549-3296 1552-4965}, url={http://dx.doi.org/10.1002/jbm.a.30969}, DOI={10.1002/jbm.a.30969}, abstractNote={AbstractWe have developed a novel approach for layer‐by‐layer growth of tissue‐engineered materials using a direct writing process known as matrix assisted pulsed laser evaporation direct write (MAPLE DW). Unlike conventional cell‐seeding methods, this technique provides the possibility for cell‐material integration prior to artificial tissue fabrication. This process also provides greater flexibility in selection and processing of scaffold materials. In addition, MAPLE DW offers rapid computer‐controlled deposition of mesoscopic voxels at high spatial resolutions. We have examined MAPLE DW processing of zirconia and hydroxyapatite scaffold materials that can provide a medical device with nearly inert and bioactive implant‐tissue interfaces, respectively. We have also demonstrated codeposition of hydroxyapatite, MG 63 osteoblast‐like cells, and extracellular matrix using MAPLE DW. We have shown that osteoblast‐like cells remain viable and retain the capacity for proliferation when codeposited with bioceramic scaffold materials. Our results on MG 63‐hydroxyapatite composites can be extended to develop other integrated cell‐scaffold structures for medical and dental applications. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007}, number={3}, journal={Journal of Biomedical Materials Research Part A}, publisher={Wiley}, author={Doraiswamy, A. and Narayan, R. J. and Harris, M. L. and Qadri, S. B. and Modi, R. and Chrisey, D. B.}, year={2007}, month={Mar}, pages={635–643} }
 @article{doraiswamy_narayan_cristescu_mihailescu_chrisey_2007, title={Laser processing of natural mussel adhesive protein thin films}, volume={27}, ISSN={0928-4931}, url={http://dx.doi.org/10.1016/j.msec.2006.05.026}, DOI={10.1016/j.msec.2006.05.026}, abstractNote={A novel laser processing technique is presented for depositing mussel adhesive protein thin films. Synthetic adhesives (e.g., acrylics, cyanoacrylates, epoxies, phenolics, polyurethanes, and silicones) have largely displaced natural adhesives in the automotive, aerospace, biomedical, electronic, and marine equipment industries over the past century. However, rising concerns over the environmental and health effects of solvents, monomers, and additives used in synthetic adhesives have led the adhesives community to seek natural alternatives. Marine mussel adhesive protein is a formaldehyde-free natural adhesive that demonstrates excellent adhesion to several classes of materials, including pure metals, metal oxides, polymers, and glasses. We have demonstrated the deposition of Mytilus edulis foot protein-1 thin films using matrix assisted pulsed laser evaporation (MAPLE). The Fourier transform infrared spectrum data suggest that the matrix assisted pulsed laser evaporation process does not cause significant damage to the chemical structure of M. edulis foot protein-1. In addition, matrix assisted pulsed laser evaporation appears to provide a better control over film thickness and film roughness than conventional solvent-based thin film processing techniques. MAPLE-deposited mussel adhesive protein thin films have numerous potential electronic, medical, and marine applications.}, number={3}, journal={Materials Science and Engineering: C}, publisher={Elsevier BV}, author={Doraiswamy, A. and Narayan, R.J. and Cristescu, R. and Mihailescu, I.N. and Chrisey, D.B.}, year={2007}, month={Apr}, pages={409–413} }
 @article{patz_doraiswamy_narayan_menegazzo_kranz_mizaikoff_zhong_bellamkonda_bumgardner_elder_et al._2007, title={Matrix assisted pulsed laser evaporation of biomaterial thin films}, volume={27}, ISSN={0928-4931}, url={http://dx.doi.org/10.1016/j.msec.2006.05.039}, DOI={10.1016/j.msec.2006.05.039}, abstractNote={In this paper, processing of biomaterial thin films using a novel physical vapor deposition process known as matrix assisted pulsed laser evaporation (MAPLE) is reviewed. The matrix assisted pulsed laser evaporation process provides excellent control over several film parameters, including thickness, roughness, homogeneity, and reliability. Deposition of dexamethasone thin films, poly (d, l) lactic acid/dexamethasone bilayer thin films, and chitosan thin films is reviewed. The results highlight the expanding role of matrix assisted pulsed laser evaporation process in biomaterials, drug delivery, and tissue engineering.}, number={3}, journal={Materials Science and Engineering: C}, publisher={Elsevier BV}, author={Patz, T.M. and Doraiswamy, A. and Narayan, R.J. and Menegazzo, N. and Kranz, C. and Mizaikoff, B. and Zhong, Y. and Bellamkonda, R. and Bumgardner, J.D. and Elder, S.H. and et al.}, year={2007}, month={Apr}, pages={514–522} }
 @article{cristescu_doraiswamy_patz_socol_grigorescu_axente_sima_narayan_mihaiescu_moldovan_et al._2007, title={Matrix assisted pulsed laser evaporation of poly(d,l-lactide) thin films for controlled-release drug systems}, volume={253}, ISSN={0169-4332}, url={http://dx.doi.org/10.1016/j.apsusc.2007.02.042}, DOI={10.1016/j.apsusc.2007.02.042}, abstractNote={We report the successful deposition of the porous polymer poly(d,l-lactide) by matrix assisted pulsed laser evaporation (MAPLE) using a KrF* excimer laser (248 nm, τ = 7 ns) operated at 2 Hz repetition rate. The chemical structure of the starting materials was preserved in the resulting thin films. Fluence played a key role in optimizing our depositions of the polymer. We demonstrated MAPLE was able to improve current approaches to grow high quality thin films of poly(d,l-lactide), including a porosity control highly required in targeted drug delivery.}, number={19}, journal={Applied Surface Science}, publisher={Elsevier BV}, author={Cristescu, R. and Doraiswamy, A. and Patz, T. and Socol, G. and Grigorescu, S. and Axente, E. and Sima, F. and Narayan, R.J. and Mihaiescu, D. and Moldovan, A. and et al.}, year={2007}, month={Jul}, pages={7702–7706} }
 @article{narayan_pant_wei_narayan_budai_2007, title={Nanostructured GaN nucleation layer for light-emitting diodes}, volume={7}, ISSN={["1533-4899"]}, DOI={10.1166/jnn.2007.670}, abstractNote={This paper addresses the formation of nanostructured gallium nitride nucleation (NL) or initial layer (IL), which is necessary to obtain a smooth surface morphology and reduce defects in h-GaN layers for light-emitting diodes and lasers. From detailed X-ray and HR-TEM studies, researchers determined that this layer consists of nanostructured grains with average grain size of 25 nm, which are separated by small-angle grain boundaries (with misorientation approximately 1 degrees), known as subgrain boundaries. Thus NL is considered to be single-crystal layer with mosaicity of about 1 degrees. These nc grains are mostly faulted cubic GaN (c-GaN) and a small fraction of unfaulted c-GaN. This unfaulted Zinc-blende c-GaN, which is considered a nonequilibrium phase, often appears as embedded or occluded within the faulted c-GaN. The NL layer contained in-plane tensile strain, presumably arising from defects due to island coalescence during Volmer-Weber growth. The 10L X-ray scans showed c-GaN fraction to be over 63% and the rest h-GaN. The NL layer grows epitaxially with the (0001) sapphire substrate by domain matching epitaxy, and this epitaxial relationship is remarkably maintained when c-GaN converts into h-GaN during high-temperature growth.}, number={8}, journal={JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY}, author={Narayan, J. and Pant, P. and Wei, W. and Narayan, R. J. and Budai, J. D.}, year={2007}, month={Aug}, pages={2719–2725} }
 @article{narayan_bhaduri_fischman_rigsbee_zhang_2007, title={Next generation biomaterials - Preface}, volume={27}, ISSN={["0928-4931"]}, DOI={10.1016/j.msec.2006.05.022}, number={3}, journal={MATERIALS SCIENCE & ENGINEERING C-BIOMIMETIC AND SUPRAMOLECULAR SYSTEMS}, author={Narayan, Roger J. and Bhaduri, Sarit B. and Fischman, Gary and Rigsbee, J. Michael and Zhang, Xinghang}, year={2007}, month={Apr}, pages={345–346} }
 @article{cristescu_doraiswamy_socol_grigorescu_axente_mihaiescu_moldovan_narayan_stamatin_mihailescu_et al._2007, title={Polycaprolactone biopolymer thin films obtained by matrix assisted pulsed laser evaporation}, volume={253}, ISSN={0169-4332}, url={http://dx.doi.org/10.1016/j.apsusc.2007.01.064}, DOI={10.1016/j.apsusc.2007.01.064}, abstractNote={We report the successful deposition of polycaprolactone polymer by MAPLE using a KrF* excimer laser (λ = 248 nm, τ = 7 ns). According to FTIR spectra the deposited films have similar chemical structure to the dropcast material. The fluence plays a key role in optimizing the performances of MAPLE-synthesized polycaprolactone structures. We demonstrated that MAPLE allows for controlling the morphology of films to the level required in targeted drug delivery of pharmacologic agents.}, number={15}, journal={Applied Surface Science}, publisher={Elsevier BV}, author={Cristescu, R. and Doraiswamy, A. and Socol, G. and Grigorescu, S. and Axente, E. and Mihaiescu, D. and Moldovan, A. and Narayan, R.J. and Stamatin, I. and Mihailescu, I.N. and et al.}, year={2007}, month={May}, pages={6476–6479} }
 @article{cristescu_cojanu_popescu_grigorescu_nastase_nastase_doraiswamy_narayan_stamatin_mihailescu_et al._2007, title={Processing of poly(1,3-bis-(p-carboxyphenoxy propane)-co-(sebacic anhydride)) 20:80 (P(CPP:SA)20:80) by matrix-assisted pulsed laser evaporation for drug delivery systems}, volume={254}, ISSN={0169-4332}, url={http://dx.doi.org/10.1016/j.apsusc.2007.09.029}, DOI={10.1016/j.apsusc.2007.09.029}, abstractNote={We have demonstrated successful thin film growth of poly(1,3-bis-(p-carboxyphenoxy, propane)-co-(sebacic anhydride)) (20:80) by matrix-assisted pulsed laser evaporation using a KrF* excimer laser (λ = 248 nm, τ = 25 ns, ν = 10 Hz). The deposited thin films have been investigated by Fourier transform infrared spectroscopy, and atomic force microscopy. We have demonstrated that the main functional groups of poly(1,3-bis-(p-carboxyphenoxy, propane)-co-(sebacic anhydride)) (20:80) are present in the deposited film. The effect of matrix on both thin film structure and surface morphology was also examined. The goal of this work is to explore laser processing of this material to create suitable constructs for drug delivery applications.}, number={4}, journal={Applied Surface Science}, publisher={Elsevier BV}, author={Cristescu, R. and Cojanu, C. and Popescu, A. and Grigorescu, S. and Nastase, C. and Nastase, F. and Doraiswamy, A. and Narayan, R.J. and Stamatin, I. and Mihailescu, I.N. and et al.}, year={2007}, month={Dec}, pages={1169–1173} }
 @article{koch_johnson_kumar_jelinek_chrisey_doraiswamy_jin_narayan_mihailescu_2007, title={Pulsed laser deposition of hydroxyapatite thin films}, volume={27}, ISSN={0928-4931}, url={http://dx.doi.org/10.1016/j.msec.2006.05.025}, DOI={10.1016/j.msec.2006.05.025}, abstractNote={Hydroxyapatite is a bioactive ceramic material that mimics the mineral composition of natural bone. This material does not possess acceptable mechanical properties for use as a bulk biomaterial; however, it does demonstrate significant potential for use as a coating on metallic orthopaedic and dental prostheses. This paper reviews recent developments involving pulsed laser deposition of hydroxyapatite thin films for medical and dental applications. The structural, mechanical, and biological properties of hydroxyapatite thin films are described. In addition, future directions in pulsed laser deposition of hydroxyapatite thin films are discussed.}, number={3}, journal={Materials Science and Engineering: C}, publisher={Elsevier BV}, author={Koch, C.F. and Johnson, S. and Kumar, D. and Jelinek, M. and Chrisey, D.B. and Doraiswamy, A. and Jin, C. and Narayan, R.J. and Mihailescu, I.N.}, year={2007}, month={Apr}, pages={484–494} }
 @article{ovsianikov_chichkov_adunka_pillsbury_doraiswamy_narayan_2007, title={Rapid prototyping of ossicular replacement prostheses}, volume={253}, ISSN={0169-4332}, url={http://dx.doi.org/10.1016/j.apsusc.2007.01.062}, DOI={10.1016/j.apsusc.2007.01.062}, abstractNote={Materials used in ossicular replacement prostheses must demonstrate appropriate biological compatibility, acoustic transmission, stability, and stiffness properties. Prostheses prepared using Teflon®, titanium, Ceravital and other conventional materials have demonstrated several problems, including migration, perforation of the tympanic membrane, difficulty in shaping the prostheses, and reactivity with the surrounding tissues. We have used two-photon polymerization for rapid prototyping of Ormocer® middle-ear bone replacement prostheses. Ormocer® surfaces fabricated using two-photon polymerization exhibited acceptable cell viability and cell growth profiles. The Ormocer® prosthesis was able to be inserted and removed from the site of use in the frozen human head without fracture. Our results demonstrate that two-photon polymerization is able to create ossicular replacement prostheses and other medical devices with a larger range of sizes, shapes and materials than other microfabrication techniques.}, number={15}, journal={Applied Surface Science}, publisher={Elsevier BV}, author={Ovsianikov, A. and Chichkov, B. and Adunka, O. and Pillsbury, H. and Doraiswamy, A. and Narayan, R.J.}, year={2007}, month={May}, pages={6603–6607} }
 @article{narayan_2007, title={Recent developments in rapid prototyping of biomaterials}, volume={2}, ISSN={1860-6768 1860-7314}, url={http://dx.doi.org/10.1002/biot.200700173}, DOI={10.1002/biot.200700173}, abstractNote={Biotechnology JournalVolume 2, Issue 11 p. 1340-1341 ForumFree Access Recent developments in rapid prototyping of biomaterials Roger Narayan, Roger Narayan roger_narayan@unc.edu Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State UniversitySearch for more papers by this author Roger Narayan, Roger Narayan roger_narayan@unc.edu Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State UniversitySearch for more papers by this author First published: 06 November 2007 https://doi.org/10.1002/biot.200700173Citations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume2, Issue11Special Issue: Singapore Biotech CrossroadsNovember 2007Pages 1340-1341 RelatedInformation}, number={11}, journal={Biotechnology Journal}, publisher={Wiley}, author={Narayan, Roger}, year={2007}, month={Nov}, pages={1340–1341} }
 @article{lin_lee_narayan_2007, title={Snapping algorithm and heterogeneous bio-tissues modeling for medical surgical simulation and product prototyping}, volume={2}, ISSN={1745-2759 1745-2767}, url={http://dx.doi.org/10.1080/17452750701487941}, DOI={10.1080/17452750701487941}, abstractNote={This paper presents a novel technique for modeling soft biological tissues as well as the development of an innovative interface for bio-manufacturing and medical applications. Heterogeneous deformable models may be used to represent the actual internal structures of deformable biological objects, which possess multiple components and non-uniform material properties. Both heterogeneous deformable object modeling and accurate haptic rendering can greatly enhance the realism and fidelity of virtual reality environments. In this paper, a tri-ray node snapping algorithm is proposed to generate a volumetric heterogeneous deformable model from a set of object interface surfaces between different materials. A constrained local static integration method is presented for simulating deformation and accurate force-feedback based on the material properties of a heterogeneous structure. Biological soft tissue modeling is used as an example to demonstrate the proposed techniques. By integrating the heterogeneous deformable model into a virtual environment, users can both observe different materials inside a deformable object as well as interact with it by touching the deformable object using a haptic device. The presented techniques can be used for surgical simulation, bio-product design, bio-manufacturing, and medical applications.}, number={2}, journal={Virtual and Physical Prototyping}, publisher={Informa UK Limited}, author={Lin, Shiyong and Lee, Yuan-Shin and Narayan, Roger J.}, year={2007}, month={Jun}, pages={89–101} }
 @article{ovsianikov_chichkov_mente_monteiro-riviere_doraiswamy_narayan_2007, title={Two photon polymerization of polymer-ceramic hybrid materials for transdermal drug delivery}, volume={4}, ISSN={["1744-7402"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000243791400003&KeyUID=WOS:000243791400003}, DOI={10.1111/j.1744-7402.2007.02115.x}, abstractNote={Three‐dimensional microneedle devices were created by femtosecond laser two photon polymerization (2PP) of organically modified ceramic (Ormocer®) hybrid materials. Arrays of in‐plane and out‐of‐plane hollow microneedles (microneedle length=800 μm, microneedle base diameter=150–300 μm) with various aspect ratios were fabricated. The fracture and penetration properties of the microneedle arrays were examined using compression load testing. In these studies, the microneedle arrays penetrated cadaveric porcine adipose tissue without fracture. Human epidermal keratinocyte viability on the Ormocer® surfaces polymerized using 2PP was similar to that on control surfaces. These results suggest that 2PP is able to create microneedle structures for transdermal drug delivery with a larger range of geometries than conventional microfabrication techniques.}, number={1}, journal={INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY}, author={Ovsianikov, A. and Chichkov, B. and Mente, P. and Monteiro-Riviere, N. A. and Doraiswamy, A. and Narayan, R. J.}, year={2007}, pages={22–29} }
 @article{rabiei_thomas_jin_narayan_cuomo_yang_ong_2006, title={A study on functionally graded HA coatings processed using ion beam assisted deposition with in situ heat treatment}, volume={200}, ISSN={["0257-8972"]}, DOI={10.1016/j.surfcoat.2005.09.027}, abstractNote={A new generation of calcium phosphate coatings with less than 1 μm thickness and graded crystallinity through the thickness of the film has been processed using ion beam assisted deposition (IBAD) and in situ heat treatment. Microstructural analysis of the film confirmed a gradual decrease of the grain size and crystallinity towards the surface, leading to nano-scale grains and eventually amorphous layer at the surface. The mechanical properties and adhesion bonding of the film have been evaluated using microscratch and nanoindentation tests and, in general, functionally graded HA films deposited using our IBAD system together with in situ heat treatment demonstrated higher modulus and hardness values than sputter-deposited films with the same thickness as well as those appearing in the literature for sintered HA. Scratch test results of both sets of samples revealed that crack formation is more common in sputter-deposited HA film than in the functionally graded HA film deposited using IBAD and in situ heat treatment. We anticipate that the functionally graded hydroxyapatite films will provide improved tissue–implant interfaces for orthopedic and dental implants.}, number={20-21}, journal={SURFACE & COATINGS TECHNOLOGY}, author={Rabiei, A and Thomas, B and Jin, C and Narayan, R and Cuomo, J and Yang, Y and Ong, JL}, year={2006}, month={May}, pages={6111–6116} }
 @article{morrison_buchanan_liaw_berry_brigmon_riester_abernathy_jin_narayan_2006, title={Electrochemical and antimicrobial properties of diamondlike carbon-metal composite films}, volume={15}, ISSN={0925-9635}, url={http://dx.doi.org/10.1016/j.diamond.2005.08.031}, DOI={10.1016/j.diamond.2005.08.031}, abstractNote={Implants containing antimicrobial metals may reduce morbidity, mortality, and healthcare costs associated with medical device-related infections. We have deposited diamondlike carbon–silver (DLC–Ag), diamondlike carbon–platinum (DLC–Pt), and diamondlike carbon–silver–platinum (DLC–AgPt) thin films using a multicomponent target pulsed laser deposition process. Transmission electron microscopy of the DLC–silver and DLC–platinum composite films revealed that the silver and platinum self-assemble into nanoparticle arrays within the diamondlike carbon matrix. The diamondlike carbon–silver film possessed hardness and Young's modulus values of 37 GPa and 331 GPa, respectively. The diamondlike carbon-metal composite films exhibited passive behavior at open-circuit potentials. Low corrosion rates were observed during testing in a phosphate-buffered saline (PBS) electrolyte. In addition, the diamondlike carbon–metal composite films were found to be immune to localized corrosion below 1000 mV (SCE). DLC–silver–platinum films demonstrated exceptional antimicrobial properties against Staphylococcus bacteria. It is believed that a galvanic couple forms between platinum and silver, which accelerates silver ion release and provides more robust antimicrobial activity. Diamondlike carbon–silver–platinum films may provide unique biological functionalities and improved lifetimes for cardiovascular, orthopaedic, biosensor, and implantable microelectromechanical systems.}, number={1}, journal={Diamond and Related Materials}, publisher={Elsevier BV}, author={Morrison, M.L. and Buchanan, R.A. and Liaw, P.K. and Berry, C.J. and Brigmon, R.L. and Riester, L. and Abernathy, H. and Jin, C. and Narayan, R.J.}, year={2006}, month={Jan}, pages={138–146} }
 @article{doraiswamy_narayan_lippert_urech_wokaun_nagel_hopp_dinescu_modi_auyeung_et al._2006, title={Excimer laser forward transfer of mammalian cells using a novel triazene absorbing layer}, volume={252}, ISSN={0169-4332}, url={http://dx.doi.org/10.1016/j.apsusc.2005.07.166}, DOI={10.1016/j.apsusc.2005.07.166}, abstractNote={We present a novel laser-based approach for developing tissue engineered constructs and other cell-based assembly's. We have deposited mesoscopic patterns of viable B35 neuroblasts using a soft direct approach of the matrix assisted pulsed laser evaporation direct write (MAPLE DW) process. As a development of the conventional direct write process, an intermediate layer of absorbing triazene polymer is used to provide gentler and efficient transfers. Transferred cells were examined for viability and proliferation and compared with that of as-seeded cells to determine the efficacy of the process. Results suggest that successful transfers can be achieved at lower fluences than usual by the incorporation of the intermediate absorbing layer thus avoiding any damage to cells and other delicate materials. MAPLE DW offers rapid computer-controlled deposition of mesoscopic voxels at high spatial resolutions, with extreme versatility in depositing combinations of natural/synthetic, living/non-living, organic/inorganic and hard/soft materials. Our approach offers a gentle and efficient transfer of viable cells which when combined with a variety of matrix materials allows development of constructs and bioactive systems in bioengineering.}, number={13}, journal={Applied Surface Science}, publisher={Elsevier BV}, author={Doraiswamy, A. and Narayan, R.J. and Lippert, T. and Urech, L. and Wokaun, A. and Nagel, M. and Hopp, B. and Dinescu, M. and Modi, R. and Auyeung, R.C.Y. and et al.}, year={2006}, month={Apr}, pages={4743–4747} }
 @article{meyers_jin_narayan_2006, title={First TMS symposium on biological materials science}, volume={26}, ISSN={0928-4931}, url={http://dx.doi.org/10.1016/j.msec.2005.08.034}, DOI={10.1016/j.msec.2005.08.034}, number={8}, journal={Materials Science and Engineering: C}, publisher={Elsevier BV}, author={Meyers, Marc A. and Jin, Sungho and Narayan, Roger}, year={2006}, month={Sep}, pages={1229–1231} }
 @article{andara_agarwal_scholvin_gerhardt_doraiswamy_jin_narayan_shih_shih_lin_et al._2006, title={Hemocompatibility of diamondlike carbon–metal composite thin films}, volume={15}, ISSN={0925-9635}, url={http://dx.doi.org/10.1016/j.diamond.2006.05.013}, DOI={10.1016/j.diamond.2006.05.013}, abstractNote={We have investigated the hemocompatibility of diamondlike carbon–silver composite and diamondlike carbon–titanium composite thin films prepared using a multicomponent target pulsed laser deposition process. These materials were examined using transmission electron microscopy, Raman spectroscopy, nanoindentation, electrochemical charge transfer testing, and platelet adhesion testing. Cross-sectional transmission electron microscopy revealed that silver self-assembles into nanoparticle arrays within the diamondlike carbon matrix in the diamondlike carbon–silver composite film. On the other hand, titanium self-assembles into alternating nanometer-thick titanium carbide layers within the diamondlike carbon matrix in the diamondlike carbon–titanium composite film. The hemocompatibility of these materials was examined using electrochemical charge transfer testing and platelet adhesion testing. A few small, widely scattered crystals were observed on the surface of the unalloyed diamondlike carbon film exposed to platelet rich plasma. On the other hand, dense fibrin networks with densely aggregated platelets were observed on the surfaces of diamondlike carbon–silver and diamondlike carbon–titanium composite thin films exposed to platelet rich plasma. Electrochemical testing revealed that the time constant for the diamondlike carbon thin film (λ = 1) was significantly higher than those for the diamondlike carbon–silver and diamondlike carbon–titanium composite thin films. These results suggest possible uses for diamondlike carbon thin films and diamondlike carbon–metal composite thin films as coatings in next generation cardiovascular implants.}, number={11-12}, journal={Diamond and Related Materials}, publisher={Elsevier BV}, author={Andara, Melanie and Agarwal, Arvind and Scholvin, Dirk and Gerhardt, Rosario A. and Doraiswamy, Anand and Jin, Chunming and Narayan, Roger J. and Shih, Chun-Che and Shih, Chun-Ming and Lin, Shing-Jong and et al.}, year={2006}, month={Nov}, pages={1941–1948} }
 @article{johnson_haluska_narayan_snyder_2006, title={In situ annealing of hydroxyapatite thin films}, volume={26}, ISSN={0928-4931}, url={http://dx.doi.org/10.1016/j.msec.2005.08.023}, DOI={10.1016/j.msec.2005.08.023}, abstractNote={Hydroxyapatite is a bioactive ceramic that mimics the mineral composition of natural bone. Unfortunately, problems with adhesion, poor mechanical integrity, and incomplete bone ingrowth limit the use of many conventional hydroxyapatite surfaces. In this work, we have developed a novel technique to produce crystalline hydroxyapatite thin films involving pulsed laser deposition and postdeposition annealing. Hydroxyapatite films were deposited on Ti–6Al–4V alloy and Si (100) using pulsed laser deposition, and annealed within a high temperature X-ray diffraction system. The transformation from amorphous to crystalline hydroxyapatite was observed at 340 °C. Mechanical and adhesive properties were examined using nanoindentation and scratch adhesion testing, respectively. Nanohardness and Young's modulus values of 3.48 and 91.24 GPa were realized in unannealed hydroxyapatite films. Unannealed and 350 °C annealed hydroxyapatite films exhibited excellent adhesion to Ti–6Al–4V alloy substrates. We anticipate that the adhesion and biological properties of crystalline hydroxyapatite thin films may be enhanced by further consideration of deposition and annealing parameters.}, number={8}, journal={Materials Science and Engineering: C}, publisher={Elsevier BV}, author={Johnson, Shevon and Haluska, Michael and Narayan, Roger J. and Snyder, Robert L.}, year={2006}, month={Sep}, pages={1312–1316} }
 @article{narayan_wei_jin_andara_agarwal_gerhardt_shih_shih_lin_su_et al._2006, title={Microstructural and biological properties of nanocrystalline diamond coatings}, volume={15}, ISSN={["1879-0062"]}, DOI={10.1016/j.diamond.2006.08.024}, abstractNote={In this study, the microstructural, mechanical, adhesion, and hemocompatibility properties of nanocrystalline diamond coatings were examined. Microwave plasma chemical vapor deposition (MPCVD) was used to deposit nanocrystalline diamond coatings on silicon (100) substrates. The coating surface consisted of faceted nodules, which exhibited a relatively wide size distribution and an average size of 60 nm. High-resolution transmission electron microscopy demonstrated that these crystals were made up of 2–4 nm rectangular crystallites. Raman spectroscopy and electron diffraction revealed that the coating contained both crystalline and amorphous phases. The microscratch adhesion study demonstrated good adhesion between the coating and the underlying substrate. Scanning electron microscopy and energy dispersive X-ray analysis revealed no crystal, fibrin, protein, or platelet aggregation on the surface of the platelet rich plasma-exposed nanocrystalline diamond coating. This study suggests that nanocrystalline diamond is a promising coating for use in cardiovascular medical devices.}, number={11-12}, journal={DIAMOND AND RELATED MATERIALS}, author={Narayan, R. J. and Wei, W. and Jin, C. and Andara, M. and Agarwal, A. and Gerhardt, R. A. and Shih, Chun-Che and Shih, Chun-Ming and Lin, Shing-Jong and Su, Yea-Yang and et al.}, year={2006}, pages={1935–1940} }
 @article{koep_jin_haluska_das_narayan_sandhage_snyder_liu_2006, title={Microstructure and electrochemical properties of cathode materials for SOFCs prepared via pulsed laser deposition}, volume={161}, ISSN={0378-7753}, url={http://dx.doi.org/10.1016/j.jpowsour.2006.03.060}, DOI={10.1016/j.jpowsour.2006.03.060}, abstractNote={Dense La0.8Sr0.2MnO3 (LSM) and La0.5Sr0.5CoO3 (LSC) films were fabricated via pulsed laser deposition (PLD) on different substrates. The crystal structures of the films were characterized via in situ X-ray diffraction and the in-plane electrical properties by impedance spectroscopy from room temperature to 700 °C. While the ablated films appeared to grow in the perovskite phase with the appropriate electrical properties when the substrate temperature was greater than 500 °C, they were amorphous when the substrate temperature was relatively low. Subsequent annealing of amorphous LSM and LSC films in air induced a rapid phase transformation to the perovskite phase. On silicon substrates, this phase transformation occurred at 450 and 600 °C, respectively.}, number={1}, journal={Journal of Power Sources}, publisher={Elsevier BV}, author={Koep, Erik and Jin, Chunming and Haluska, Michael and Das, Rupak and Narayan, Roger and Sandhage, Ken and Snyder, Robert and Liu, Meilin}, year={2006}, month={Oct}, pages={250–255} }
 @article{sumerel_lewis_doraiswamy_deravi_sewell_gerdon_wright_narayan_2006, title={Piezoelectric ink jet processing of materials for medicaland biological applications}, volume={1}, ISSN={1860-6768 1860-7314}, url={http://dx.doi.org/10.1002/biot.200600123}, DOI={10.1002/biot.200600123}, abstractNote={AbstractMany advanced medical and biological devices require microscale patterning of cells, proteins, and other biological materials. This article describes the use of piezoelectric ink jet processing in the fabrication of biosensors, cell‐based assays, and other microscale medical devices. A microelectromechanical system‐based piezoelectric transducer was used to develop uniform fluid flow through nozzles and to prepare well‐defined microscale patterns of proteins, monofunctional acrylate ester, sinapinic acid, deoxyribonucleic acid (DNA), and DNA scaffolds on relevant substrates. Our results demonstrate that piezoelectric ink jet deposition is a powerful non‐contact, non‐destructive additive process for developing biosensors, cell culture systems, and other devices for medical and biological applications.}, number={9}, journal={Biotechnology Journal}, publisher={Wiley}, author={Sumerel, Jan and Lewis, John and Doraiswamy, Andy and Deravi, Leila F. and Sewell, Sarah L. and Gerdon, Aren E. and Wright, David W. and Narayan, Roger J.}, year={2006}, month={Sep}, pages={976–987} }
 @article{lacour_wagner_narayan_li_suo_2006, title={Stiff subcircuit islands of diamondlike carbon for stretchable electronics}, volume={100}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.2210170}, DOI={10.1063/1.2210170}, abstractNote={Stretchable electronics on elastomeric substrates requires fragile and brittle device materials to be placed on stiff, mechanical distinct subcircuit islands. We deposited a diamondlike carbon (DLC) film at room temperature on a silicone substrate by pulsed laser ablation, and patterned the film into an array of 200×200μm2 islands. When the substrate was uniaxially stretched to a strain of 25%, the islands remained adherent to the substrate and only deformed by ∼5%, while the exposed substrate stretched by more than 30%. A row of 11 DLC islands interconnected with gold stretchable metallization maintained end-to-end electrical conduction during a mechanical cycle to 20% tensile strain. This demonstration of electrically interconnected stiff islands on silicone illustrates two important steps toward fully integrated, elastically stretchable electronics.}, number={1}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Lacour, Stéphanie P. and Wagner, Sigurd and Narayan, Roger J. and Li, Teng and Suo, Zhigang}, year={2006}, month={Jul}, pages={014913} }
 @article{jin_narayan_2006, title={Structural and optical properties of hexagonal MgxZn1-xO thin films}, volume={35}, ISSN={["1543-186X"]}, DOI={10.1007/BF02692542}, number={5}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Jin, Chunming and Narayan, Roger J.}, year={2006}, month={May}, pages={869–876} }
 @article{narayan_hobbs_jin_rabiei_2006, title={The use of functionally gradient materials in medicine}, volume={58}, ISSN={1047-4838 1543-1851}, url={http://dx.doi.org/10.1007/S11837-006-0142-5}, DOI={10.1007/S11837-006-0142-5}, number={7}, journal={JOM}, publisher={Springer Science and Business Media LLC}, author={Narayan, Roger J. and Hobbs, Linn W. and Jin, Chunming and Rabiei, Afsaneh}, year={2006}, month={Jul}, pages={52–56} }
 @article{jin_zhou_wei_narayan_2006, title={Three-dimensional self-organization of crystalline gold nanoparticles in amorphous alumina}, volume={89}, DOI={10.1063/1.2422910}, abstractNote={Multilayered heterostructures containing gold nanoparticles embedded in amorphous alumina matrices were deposited on silicon (001) substrates using pulsed laser deposition. The three-dimensional ordering of gold nanoparticles within these multilayered heterostructures was investigated using cross-sectional transmission electron microscopy and image Fourier transformation. Self-organization of gold nanoparticles along the vertical direction was observed in films grown at 20 and at 320°C. Self-organization occurred by means of two different growth modes; both vertically correlated growth (top-on-top) and anticorrelated growth (top-on-middle) mechanisms were observed. The results of these studies suggest that the driving force for vertical ordering in this material is related to the long-range elastic interactions among the nanoparticles within the growing films.}, number={26}, journal={Applied Physics Letters}, author={Jin, C. M. and Zhou, H. H. and Wei, W. and Narayan, R.}, year={2006} }
 @article{doraiswamy_jin_narayan_mageswaran_mente_modi_auyeung_chrisey_ovsianikov_chichkov_2006, title={Two photon induced polymerization of organic-inorganic hybrid biomaterials for microstructured medical devices}, volume={2}, ISSN={["1878-7568"]}, DOI={10.1016/j.actbio.2006.01.004}, abstractNote={Three-dimensional microstructured medical devices, including microneedles and tissue engineering scaffolds, were fabricated by two photon induced polymerization of Ormocer® organic–inorganic hybrid materials. Femtosecond laser pulses from a titanium:sapphire laser were used to break chemical bonds on Irgacure® 369 photoinitiator within a small focal volume. The radicalized starter molecules reacted with Ormocer® US-S4 monomers to create radicalized polymolecules. The desired structures are fabricated by moving the laser focus in three dimensions using a galvano-scanner and a micropositioning system. Ormocer® surfaces fabricated using two photon induced polymerization demonstrated acceptable cell viability and cell growth profiles against B35 neuroblast-like cells and HT1080 epithelial-like cells. Lego®-like interlocking tissue engineering scaffolds and microneedle arrays with unique geometries were created using two photon induced polymerization. These results suggest that two photon induced polymerization is able to create medical microdevices with a larger range of sizes, shapes, and materials than chemical isotropic etching, injection molding, reactive ion etching, surface micromachining, bulk micromachining, polysilicon micromolding, lithography–electroforming–replication, or other conventional microfabrication techniques.}, number={3}, journal={ACTA BIOMATERIALIA}, author={Doraiswamy, A and Jin, C and Narayan, RJ and Mageswaran, P and Mente, P and Modi, R and Auyeung, R and Chrisey, DB and Ovsianikov, A and Chichkov, B}, year={2006}, month={May}, pages={267–275} }
 @article{doraiswamy_patz_narayan_dinescu_modi_auyeung_chrisey_2006, title={Two-dimensional differential adherence of neuroblasts in laser micromachined CAD/CAM agarose channels}, volume={252}, ISSN={0169-4332}, url={http://dx.doi.org/10.1016/j.apsusc.2005.07.158}, DOI={10.1016/j.apsusc.2005.07.158}, abstractNote={Laser micromachining of hydrophobic gels into CAD/CAM patterns was used to develop differentially adherent surfaces and induce the attachment of B35 rat neuroblasts that would later form engineered nerve bundles. Narrow channels, 60–400 μm wide, were micromachined in a 2% agarose gel using an ArF laser, and subsequently filled with an extracellular matrix gel. Upon the addition of 1 ml of a 2 × 104 cells/ml neuroblast suspension, the cells selectively adhered to the ECM-lined channels in a non-confluent manner and we monitored their growth at various time points. The adherent neuroblasts were fluorescently imaged with a propidium iodide live/dead assay, which revealed that the cells were alive within the channels. After 72 h growth, the neuroblasts grew, proliferated, and differentiated into nerve bundles. The fully grown 1 cm long nerve bundle organoids maintained an aspect ratio on the order of 100. The results presented in this paper provide the foundation for laser micromachining technique to develop bioactive substrates for development of three-dimensional tissues. Laser micromachining offers rapid prototyping of substrates, excellent resolution, control of pattern depth and dimensions, and ease of fabrication.}, number={13}, journal={Applied Surface Science}, publisher={Elsevier BV}, author={Doraiswamy, A. and Patz, T. and Narayan, R.J. and Dinescu, M. and Modi, R. and Auyeung, R.C.Y. and Chrisey, D.B.}, year={2006}, month={Apr}, pages={4748–4753} }
 @article{katiyar_jin_narayan_2005, title={Electrical properties of amorphous aluminum oxide thin films}, volume={53}, ISSN={1359-6454}, url={http://dx.doi.org/10.1016/j.actamat.2005.02.027}, DOI={10.1016/j.actamat.2005.02.027}, abstractNote={Silicon oxide (SiO2) gate length, gate thickness, junction depth, and source/drain extension scaling have allowed metal–oxide–semiconductor (MOS) gate dimensions to approach the current ⩽100 nm range. High dielectric constant materials for gate insulation and low resistivity junctions must be developed in order to enable further scaling of these devices. Aluminum oxide (Al2O3), with a bandgap of 9.9 eV, is an especially promising material for use as a gate insulator; however, conventional Al2O3 processing techniques suffer from excessive thermal requirements. We have grown α-Al2O3 thin films directly on silicon (1 0 0) at room temperature using pulsed laser deposition (PLD). Atomic-resolution transmission electron microscopy, Z-contrast scanning transmission electron microscopy, capacitance–voltage measurements, and current–voltage measurements were used to determine the nanoscale features and electrical properties of amorphous Al2O3 thin films. Our results suggest that amorphous Al2O3 films prepared using pulsed laser deposition may serve as high dielectric constant materials for next generation electronic devices.}, number={9}, journal={Acta Materialia}, publisher={Elsevier BV}, author={Katiyar, P. and Jin, C. and Narayan, R.J.}, year={2005}, month={May}, pages={2617–2622} }
 @article{jin_narayan_tiwari_zhou_kvit_narayan_2005, title={Epitaxial growth of zinc oxide thin films on silicon}, volume={117}, ISSN={0921-5107}, url={http://dx.doi.org/10.1016/j.mseb.2004.12.003}, DOI={10.1016/j.mseb.2004.12.003}, abstractNote={Epitaxial zinc oxide thin films were grown on Si(1 1 1) using aluminum nitride and magnesium oxide/titanium nitride buffer layers. The resultant films were examined using transmission electron microscopy, X-ray diffraction, electrical conductivity, and photoluminescence spectroscopy. The following epitaxial relationships were observed in the ZnO/AlN/Si(1 1 1) heterostructure: ZnO[0 0 0 1] || AlN[0 0 0 1] || Si[1 1 1] along the growth direction, and ZnO[21¯1¯0] || AlN[21¯1¯0] || Si[011¯] along the in-plane direction. Domain-matching epitaxial growth of TiN on Si(1 1 1) substrate allows successful epitaxial growth of MgO and ZnO layers in a ZnO/MgO/TiN/Si(1 1 1) heterostructure. The epitaxial relationships observed for this heterostructure were ZnO[0 0 0 1] || MgO/TiN/Si[1 1 1] along the growth direction and ZnO[21¯1¯0] || MgO/TiN/Si[011¯] along in-plane direction. The resultant ZnO films demonstrate excellent electrical and optical properties. ZnO thin films exhibit extremely bright ultraviolet luminescence with relatively weak green-band emission.}, number={3}, journal={Materials Science and Engineering: B}, publisher={Elsevier BV}, author={Jin, Chunming and Narayan, Roger and Tiwari, Ashutosh and Zhou, Honghui and Kvit, Alex and Narayan, Jagdish}, year={2005}, month={Mar}, pages={348–354} }
 @article{narayan_2005, title={Hydroxyapatite–diamondlike carbon nanocomposite films}, volume={25}, ISSN={0928-4931}, url={http://dx.doi.org/10.1016/j.msec.2005.01.023}, DOI={10.1016/j.msec.2005.01.023}, abstractNote={Hydroxyapatite is a bioactive ceramic that mimics the mineral composition of natural bone. Conventional plasma-sprayed hydroxyapatite coatings demonstrate poor adhesion and poor mechanical integrity. We have developed hydroxyapatite–diamondlike carbon bilayer film. The diamondlike carbon interlayer serves to prevent metal ion release and improve adhesion of the hydroxyapatite film. These films were characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, nanoindentation, and microscratch adhesion testing. Based on the results of this study, hydroxyapatite–diamondlike carbon bilayers demonstrate promise for use in several orthopedic implants.}, number={3}, journal={Materials Science and Engineering: C}, publisher={Elsevier BV}, author={Narayan, Roger J.}, year={2005}, month={May}, pages={398–404} }
 @article{narayan_jin_doraiswamy_mihailescu_jelinek_ovsianikov_chichkov_chrisey_2005, title={Laser Processing of Advanced Bioceramics}, volume={7}, ISSN={1438-1656 1527-2648}, url={http://dx.doi.org/10.1002/adem.200500155}, DOI={10.1002/adem.200500155}, abstractNote={AbstractIn this article, laser processing of diamondlike carbon‐metal nanocomposite films, hydroxyapatite‐osteoblast composites, and Ormocer® microdevices for medical applications is described. Pulsed laser deposition has been used to process diamondlike carbon‐silver‐platinum nanocomposite films that provide hardness, wear resistance, corrosion resistance, and antimicrobial functionalities to cardiovascular, orthopaedic, biosensor, and MEMS devices. Laser direct writing has been used for fabricating integrated cell‐scaffold structures. Two photon induced polymerization has been used to create Ormocer® tissue engineering scaffolds and microneedles with unique geometries. Pulsed laser deposition, laser direct write, and two photon induced polymerization techniques may provide medical engineers with advanced biomaterials that possess unique structures and functionalities.}, number={12}, journal={Advanced Engineering Materials}, publisher={Wiley}, author={Narayan, R. J. and Jin, C. and Doraiswamy, A. and Mihailescu, I. N. and Jelinek, M. and Ovsianikov, A. and Chichkov, B. and Chrisey, D. B.}, year={2005}, month={Dec}, pages={1083–1098} }
 @article{narayan_2005, title={Laser processing of diamond-like carbon–metal composites}, volume={245}, ISSN={0169-4332}, url={http://dx.doi.org/10.1016/j.apsusc.2004.11.026}, DOI={10.1016/j.apsusc.2004.11.026}, abstractNote={Diamond-like carbon (DLC) is a hydrogen-free amorphous material that contains a large fraction of sp3-hybridized carbon atoms. DLC exhibits hardness, corrosion resistance, and wear resistance properties close to those of diamond. Unfortunately, DLC films contain a large amount of compressive stresses and exhibit poor adhesion to many metal substrates. We have adopted a novel pulsed laser deposition process to incorporate metal atoms into diamond-like carbon films. Visible Raman spectroscopy data suggest that DLC–metal composite films possess less internal compressive stress than as-prepared DLC films. DLC–metal composite films have several potential applications, including use in machine tools and medical prostheses.}, number={1-4}, journal={Applied Surface Science}, publisher={Elsevier BV}, author={Narayan, Roger Jagdish}, year={2005}, month={May}, pages={420–430} }
 @article{narayan_2005, title={Nanostructured diamondlike carbon thin films for medical applications}, volume={25}, ISSN={0928-4931}, url={http://dx.doi.org/10.1016/j.msec.2005.01.026}, DOI={10.1016/j.msec.2005.01.026}, abstractNote={Diamondlike carbon (DLC) is an amorphous form of carbon that may contain a high fraction of sp3-hybridized carbon atoms. DLC thin films possess high hardness values, low coefficient of friction values, chemical inertness, and compatibility with human cells. The cardiovascular, orthopedic, ophthalmic, biosensor, and microelectromechanical system (MEMS) device applications for diamondlike carbon thin films are reviewed. Finally, processing of nanostructured diamondlike carbon thin films for medical applications is presented.}, number={3}, journal={Materials Science and Engineering: C}, publisher={Elsevier BV}, author={Narayan, Roger J.}, year={2005}, month={May}, pages={405–416} }
 @article{cristescu_patz_narayan_menegazzo_mizaikoff_mihaiescu_messersmith_stamatin_mihailescu_chrisey_2005, title={Processing of mussel adhesive protein analog thin films by matrix assisted pulsed laser evaporation}, volume={247}, ISSN={0169-4332}, url={http://dx.doi.org/10.1016/j.apsusc.2005.01.066}, DOI={10.1016/j.apsusc.2005.01.066}, abstractNote={Mussel adhesive proteins are a new class of biologically-derived materials that possess unique biocompatibility, bioactivity, and adhesion properties. We have demonstrated successful thin film growth of 3,4-dihydroxyphenyl-l-alanine modified poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (DOPA modified- PEO-PPO-PEO) block copolymer, a mussel adhesive protein analog, using matrix assisted pulsed laser evaporation. We have demonstrated that the main functional groups of the mussel adhesive protein analog are present in the transferred film. The effect of increasing of chain length of the mussel adhesive protein analog on film structure was also examined. These novel polymer thin films could have numerous medical and technological applications if their thin film properties are similar to what is found in bulk. This is the first report of successful MAPLE deposition of this material as thin films.}, number={1-4}, journal={Applied Surface Science}, publisher={Elsevier BV}, author={Cristescu, R. and Patz, T. and Narayan, R.J. and Menegazzo, N. and Mizaikoff, B. and Mihaiescu, D.E. and Messersmith, P.B. and Stamatin, I. and Mihailescu, I.N. and Chrisey, D.B.}, year={2005}, month={Jul}, pages={217–224} }
 @article{patz_cristescu_narayan_menegazzo_mizaikoff_messersmith_stamatin_mihailescu_chrisey_2005, title={Processing of mussel-adhesive protein analog copolymer thin films by matrix-assisted pulsed laser evaporation}, volume={248}, ISSN={0169-4332}, url={http://dx.doi.org/10.1016/j.apsusc.2005.03.056}, DOI={10.1016/j.apsusc.2005.03.056}, abstractNote={We have demonstrated the successful thin film growth of a mussel-adhesive protein analog, DOPA-modified PEO–PPO–PEO block copolymer PF127, using matrix-assisted pulsed laser evaporation (MAPLE). The MAPLE-deposited thin films were examined using Fourier transform infrared spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and contact-angle measurements. We have found that the main functional groups of the mussel-adhesive protein analog are present in the transferred film. These adhesive materials have several potential electronic, medical, and marine applications.}, number={1-4}, journal={Applied Surface Science}, publisher={Elsevier BV}, author={Patz, T. and Cristescu, R. and Narayan, R. and Menegazzo, N. and Mizaikoff, B. and Messersmith, P.B. and Stamatin, I. and Mihailescu, I.N. and Chrisey, D.B.}, year={2005}, month={Jul}, pages={416–421} }
 @article{narayan_2005, title={Pulsed laser deposition of functionally gradient diamondlike carbon–metal nanocomposites}, volume={14}, ISSN={0925-9635}, url={http://dx.doi.org/10.1016/j.diamond.2004.12.047}, DOI={10.1016/j.diamond.2004.12.047}, abstractNote={Diamondlike carbon thin films possess atomic smoothness, chemical inertness, and hardness properties close to those of diamond. Unfortunately, these films exhibit poor adhesion to metals and polymers used in medical prostheses. This paper presents the processing and characterization of diamondlike carbon–copper, diamondlike carbon–silver, diamondlike carbon–silicon, and diamondlike carbon–titanium nanocomposite films with enhanced adhesion to Ti–6Al–4V alloy substrates. Silver forms nanoparticle arrays within the diamondlike carbon matrix in diamondlike carbon–silver nanocomposite films. On the other hand, titanium forms layers of titanium carbide within the diamondlike carbon matrix in diamondlike carbon–titanium nanocomposite films. These films were characterized using electron energy loss spectroscopy, transmission electron microscopy, Raman spectroscopy, Rutherford backscattering spectrometry, nanoindentation, wear testing, and scratch adhesion testing. Diamondlike carbon–metal nanocomposite films have numerous potential medical applications, including use on the surfaces of medical prostheses.}, number={8}, journal={Diamond and Related Materials}, publisher={Elsevier BV}, author={Narayan, Roger Jagdish}, year={2005}, month={Aug}, pages={1319–1330} }
 @article{narayan_berry_brigmon_2005, title={Structural and biological properties of carbon nanotube composite films}, volume={123}, ISSN={0921-5107}, url={http://dx.doi.org/10.1016/j.mseb.2005.07.007}, DOI={10.1016/j.mseb.2005.07.007}, abstractNote={Carbon nanotube composite films have been developed that exhibit unusual structural and biological properties. These novel materials have been created by pulsed laser ablation of graphite and bombardment of nitrogen ions at temperatures between 600 and 700 °C. High-resolution transmission electron microscopy and radial distribution function analysis demonstrate that this material consists of sp2-bonded concentric ribbons that are wrapped approximately 15° normal to the silicon substrate. The interlayer order in this material extends to approximately 15–30 Å. X-ray photoelectron spectroscopy and Raman spectroscopy data suggest that this material is predominantly trigonally coordinated. The carbon nanotube composite structure results from the use of energetic ions, which allow for non-equilibrium growth of graphitic planes. In vitro testing has revealed significant antimicrobial activity of carbon nanotube composite films against Staphylococcus aureus and Staphylococcus warneri colonization. Carbon nanotube composite films may be useful for inhibiting microorganism attachment and biofilm formation in hemodialysis catheters and other medical devices.}, number={2}, journal={Materials Science and Engineering: B}, publisher={Elsevier BV}, author={Narayan, Roger J. and Berry, C.J. and Brigmon, R.L.}, year={2005}, month={Nov}, pages={123–129} }
 @article{patz_doraiswamy_narayan_he_zhong_bellamkonda_modi_chrisey_2006, title={Three-dimensional direct writing of B35 neuronal cells}, volume={78B}, ISSN={1552-4973 1552-4981}, url={http://dx.doi.org/10.1002/jbm.b.30473}, DOI={10.1002/jbm.b.30473}, abstractNote={AbstractWe have demonstrated two‐dimensional and three‐dimensional transfer of B35 neuronal cells onto and within polymerized Matrigel® substrates, using matrix‐assisted pulsed laser evaporation‐direct write (MDW). The B35 cells were transferred from a quartz ribbon to depths of up to 75 μm by systematically varying the fluence emitted from the ArF (λ = 193 nm) laser source. MDW‐transferred cells were examined using terminal deoxynucleotidyl transferase biotin‐dUTP nick end labeling (TUNEL), 4′,6‐diamidino‐2‐phenylindole (DAPI), and α‐tubulin staining. Confocal microscopy has shown that the transferred B35 cells extended their axons outward in three dimensions within the polymerized Matrigel substrate. The B35 cells made axonal connections and formed a three‐dimensional neural network within 72 h after MDW transfer. In addition, TUNEL staining demonstrated that only 3% of the B35 cells underwent apoptosis after being transferred using the MDW process. MDW and other emergent direct write processes may provide unique approaches for creating layered, heterogeneous, three‐dimensional cell‐seeded scaffolds for use in peripheral nerve repair. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006}, number={1}, journal={Journal of Biomedical Materials Research Part B: Applied Biomaterials}, publisher={Wiley}, author={Patz, T. M. and Doraiswamy, A. and Narayan, R. J. and He, W. and Zhong, Y. and Bellamkonda, R. and Modi, R. and Chrisey, D. B.}, year={2006}, pages={124–130} }
 @article{patz_doraiswamy_narayan_modi_chrisey_2005, title={Two-dimensional differential adherence and alignment of C2C12 myoblasts}, volume={123}, ISSN={0921-5107}, url={http://dx.doi.org/10.1016/j.mseb.2005.08.088}, DOI={10.1016/j.mseb.2005.08.088}, abstractNote={Surface microstructure is a critical parameter for scaffolds used in skeletal muscle tissue engineering. We have developed micromachined surfaces using matrix assisted pulsed laser evaporation-direct write (MAPLE-DW) that demonstrate differential adherence of C2C12 myoblast cells. The 60–400 μm diameter channels were micromachined onto 2% agarose surfaces using an ArF excimer laser and lined with Matrigel® basement membrane matrix solution. Suspensions containing C2C12 myoblast cells were then placed on the surface of these micromachined channels. The C2C12 myoblast cells aligned themselves parallel to the 60–150 μm channels. Live/dead assays over 72 h demonstrated that cell number, cell size, and number of nuclei per cell increased within these channels. In addition, some of the myoblasts fused and differentiated into multinucleated myotubes. These results provide the basis for the development of direct-write scaffolds for skeletal muscle tissue engineering.}, number={3}, journal={Materials Science and Engineering: B}, publisher={Elsevier BV}, author={Patz, T.M. and Doraiswamy, A. and Narayan, R.J. and Modi, R. and Chrisey, D.B.}, year={2005}, month={Nov}, pages={242–247} }
 @article{jin_tiwari_narayan_2005, title={Ultraviolet-illumination-enhanced photoluminescence effect in zinc oxide thin films}, volume={98}, ISSN={["1089-7550"]}, DOI={10.1063/1.2108156}, abstractNote={We report an enhancement effect of ultraviolet illumination on the photoluminescence intensities of zinc oxide thin films. Large-grain ⟨0001⟩-textured zinc oxide thin films were deposited on amorphous-fused silica substrates using pulsed laser deposition. We found that the intensities of excitonic emission and green-band emission increased with ultraviolet light exposure time until a maximum value was achieved. We attribute this ultraviolet radiation enhancement effect to oxygen desorption on the surface of the zinc oxide thin film. We have proposed a phenomenological model to explain this interesting photoluminescence behavior.}, number={8}, journal={JOURNAL OF APPLIED PHYSICS}, author={Jin, CM and Tiwari, A and Narayan, RJ}, year={2005}, month={Oct} }
 @article{sharma_kalyanaraman_narayan_oktyabrsky_narayan_2001, title={Carbon nanotube composites synthesized by ion-assisted pulsed laser deposition}, volume={79}, ISSN={["0921-5107"]}, DOI={10.1016/s0921-5107(00)00558-4}, abstractNote={We have synthesized thin CNx films on Si (100) substrate at high temperatures (600 and 700°C) by nitrogen ion-assisted pulsed laser deposition (PLD). The bonding characteristics and microstructure determinations have been accomplished using X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM), respectively. The radial distribution function (RDF) analysis of the electron diffraction patterns was performed to determine the short range atomic order in these films. The results reveal the presence of carbon predominantly in the trigonally-coordinated state with small fractions of nitrogen (upto 20 at.%) bonded to carbon. The electron diffraction and the high resolution images in cross-section view reveal that there is a textured growth of nanotube or graphite-like ribbons. The plan-view specimens show high resolution images with bended layers similar to that of onion or nanotube like features. The kinetics of the ions assisting the growth is assumed to be important to grow the basal planes (00l) of graphite perpendicular to the substrate. The large anisotropic surface energies in two perpendicular directions in graphite suggest that ions can create nonequilibrium conditions to alter the growth mode of graphitic planes. The importance of ion-assisted PLD to grow novel nanotube or fullerenelike structure in the form of thin film composites for electron field emission devices is emphasized.}, number={2}, journal={MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY}, author={Sharma, AK and Kalyanaraman, R and Narayan, RJ and Oktyabrsky, S and Narayan, J}, year={2001}, month={Jan}, pages={123–127} }
 @article{wei_sankar_sharma_oktyabrsky_narayan_narayan_2000, title={Atomic structure, electrical properties, and infrared range optical properties of diamondlike carbon films containing foreign atoms prepared by pulsed laser deposition}, volume={15}, ISSN={["0884-2914"]}, DOI={10.1557/jmr.2000.0094}, abstractNote={We investigated the atomic structure, electrical, and infrared range optical properties of diamondlike carbon (DLC) films containing alloy atoms (Cu, Ti, or Si) prepared by pulsed laser deposition. Radial distribution function (RDF) analysis of these films showed that they are largely sp3 bonded. Both pure DLC and DLC + Cu films form a Schottky barrier with the measuring probe, whereas DLC + Ti films behave like a linear resistor. Pure DLC films and those containing Cu exhibit p-type conduction, and those containing Ti and Si have n-type conduction. Photon-induced conduction is observed for pure DLC, and the mechanism is discussed in terms of low-density gap states of highly tetrahedral DLC. Our results are consistent with relative absence of gap states in pure DLC, in accordance with theoretical prediction by Drabold et al.37 Temperature dependence of conductivity of DLC + Cu shows a behavior σ ∞ exp(−B/T1/2), instead of the T−1/4 law (Mott–Davis law). Contributions from band-to-band transitions, free carriers, and phonons to the emissivity spectrum are clearly identified in pure DLC films. The amorphous state introduces a large contribution from localized states. Incorporation of a small amount of Si in the DLC does not change the general feature of emissivity spectrum but enhances the contribution from the localized states. Cu and Ti both enhance the free carrier and the localized state contributions and make the films a black body.}, number={3}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Wei, Q and Sankar, J and Sharma, AK and Oktyabrsky, S and Narayan, J and Narayan, RJ}, year={2000}, month={Mar}, pages={633–641} }
 @article{sharma_narayan_narayan_jagannadham_2000, title={Structural and tribological characteristics of diamond-like carbon films deposited by pulsed laser ablation}, volume={77}, ISSN={["0921-5107"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0034250566&partnerID=MN8TOARS}, DOI={10.1016/s0921-5107(00)00434-7}, abstractNote={Diamond-like carbon (DLC) films were deposited by pulsed laser ablation (PLA) on Si (100) and Ti–6Al–4V alloy substrates at four different temperatures. The bonding characteristics of the films were studied by X-ray photoelectron (XPS) and Raman spectroscopy techniques. The ratio of tetrahedral to trigonally coordinated carbon atoms was estimated by XPS successfully. The fraction of tetrahedrally bonded atoms in the films deposited on Si at room temperature was estimated to be ∼63 at.% which decreased to ∼33 at.% as the substrate temperature increased to 400°C. The Raman spectroscopy results of these specimens agree qualitatively with these observations. Also, using Raman spectroscopy, the residual compressive stress was also estimated in fully adherent films on Si substrate to be ∼3 GPa with reference to the value of stress present in a free-standing peeled off film from the Ti-alloy substrate. This value is consistent with the residual stresses estimated in the earlier results. The abrasive wear rates have been correlated during the initial stages of the well adhered films with the sp3/sp2 ratios. The importance of suitable dopants and the interfacial interlayers in reducing internal compressive stresses in these films is discussed.}, number={2}, journal={MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY}, author={Sharma, AK and Narayan, RJ and Narayan, J and Jagannadham, K}, year={2000}, month={Aug}, pages={139–143} }
 @article{godbole_narayan_xu_narayan_sankar_1999, title={Diamond films and composites on cobalt-chromium alloys}, volume={58}, ISSN={["0921-5107"]}, DOI={10.1016/s0921-5107(98)00430-9}, abstractNote={Abstract Silicon, aluminum nitride (AlN) and titanium carbide (TiC) layers were deposited on cobalt–chromium alloys to investigate their utility as buffer layers for the synthesis of diamond films and composites. Silicon and aluminum nitride were found to react with the substrate at diamond deposition temperatures, via out-diffusion of cobalt from the substrate. The layers of titanium carbide, on the other hand, were found to be useful as a diffusion barrier for outward diffusion of cobalt and inward diffusion of carbon during diamond deposition, thus making enhanced nucleation and growth of high quality diamond possible. The continuous diamond coatings thus formed, however, tend to bulge and then crack due to thermal expansion mismatches between the TiC coated substrate and the overlayer diamond film. Composite coatings of AlN–diamond and TiC–diamond have, therefore, been synthesized by sequential deposition of component materials. These composite coatings consist of randomly interconnected micron sized diamond crystallites which are primarily surrounded by buffer material (AlN or TiC) while the contact area between neighbouring diamond crystallites is minimum. The presence of such a discontinuous morphology of diamond crystallites renders more toughness and also leads to compensation of stresses in localized regions (local stress management) and thus reduces bulging and subsequent delamination effects.}, number={3}, journal={MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY}, author={Godbole, VP and Narayan, R and Xu, Z and Narayan, J and Sankar, J}, year={1999}, month={Mar}, pages={251–257} }
 @article{wei_narayan_sharma_sankar_narayan_1999, title={Preparation and mechanical properties of composite diamond-like carbon thin films}, volume={17}, ISSN={["0734-2101"]}, DOI={10.1116/1.582074}, abstractNote={We have investigated mechanical properties of diamond-like carbon (DLC) thin films, particularly the internal compressive stress and ways to alleviate it. Foreign atoms such as copper, titanium, and silicon were incorporated into the DLC films during pulsed laser deposition. The chemical composition of the doped films was determined using Rutherford backscattering spectrometry (RBS) and x-ray photoelectron spectroscopy (XPS). Optical microscopy of the doped films showed that DLC films containing Cu exhibit much less particulate density as compared to the films containing Ti and Si. Visible Raman spectroscopy was used to characterize the films. The effect of dopants on the Raman spectrum was analyzed in terms of peak shape and position. Optical microscopy of the pure DLC of a certain thickness showed severe buckling. The mechanisms of adhesion associated with DLC coatings were discussed. Qualitative scratch tests on the specimens showed that pure DLC films have relatively poor adhesion due to a large compressive stress, while the doped DLC films exhibit much improved adhesion. Wear tests show improved wear resistance in the doped DLC coatings. Nanoindentation results suggest that pure DLC has an average hardness above 40 GPa and effective Young’s modulus above 200 GPa. The doped DLC films showed slightly decreased hardness and Young’s modulus as compared to pure DLC films. These results can be rationalized by analyzing the internal stress reduction as derived from Raman G-peak shift to lower wavenumbers. A preliminary interpretation of the stress reduction mechanism is discussed.}, number={6}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS}, author={Wei, Q and Narayan, RJ and Sharma, AK and Sankar, J and Narayan, J}, year={1999}, pages={3406–3414} }
 @article{wei_narayan_narayan_sankar_sharma_1998, title={Improvement of wear resistance of pulsed laser deposited diamond-like carbon films through incorporation of metals}, volume={53}, ISSN={["0921-5107"]}, DOI={10.1016/s0921-5107(98)00150-0}, abstractNote={We have investigated the characteristics of diamond-like carbon (DLC), DLC doped with Cu, and DLC doped with Ti deposited by a sequential pulsed laser ablation of two targets. The composition of these films was determined by Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy (XPS). Raman spectroscopy and transmission electron microscopy studies showed typical features of DLC with a high fraction of sp3 bonded carbon in the doped films as well as in the undoped films. Wear resistance measurements made on the samples by means of the `crater grinding method' showed that DLC+2.75% Ti has the highest wear resistance, while that of pure DLC has the lowest amongst the samples. Careful analysis of the Raman data indicates a significant shift to shorter wavelength with the addition of metal, which means that the compressive stress in the DLC films has been reduced. We envisaged that the reduction in the compressive stress promotes the wear resistance of the coatings. The XPS studies showed evidence for the formation of Ti–C bonding in the Ti doped sample. Thus metal-doped DLC coatings are expected to improve the tribological properties and enhance the performance of components coated with metal-doped DLC.}, number={3}, journal={MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY}, author={Wei, Q and Narayan, RJ and Narayan, J and Sankar, J and Sharma, AK}, year={1998}, month={May}, pages={262–266} }
 @inproceedings{wei_sharma_narayan_ravindra_oktyabrsky_sankar_muth_kolbas_narayan_1998, title={Microstructure and IR range optical properties of pure DLC and DLC containing dopants prepared by pulsed laser deposition}, booktitle={Advances in laser ablation of materials: Symposium held April 13-16, 1998, San Francisco, California, U.S.A.  (Materials Research Society symposia proceedings ; v. 526).}, publisher={Warrendale, Pa.: Materials Research Society}, author={Wei, Q. and Sharma, A. K. and Narayan, R. J. and Ravindra, N. M. and Oktyabrsky, S. and Sankar, J. and Muth, J. F. and Kolbas, R. M. and Narayan, J.}, year={1998}, pages={331} }
 @book{narayan, title={Advances in bioceramics and biotechnologies a collection of papers presented at the 8th Pacific Rim Conference on Ceramic and Glass Technology, May 31-June 5, 2009, Vancouver, British Columbia}, publisher={Westerville: American Ceramic Society ;|aHoboken, NJ: John Wiley}, author={Narayan, Roger} }
 @book{roger narayan, title={Advances in bioceramics and porous ceramics}, publisher={Hoboken, NJ: John Wiley ;|aChichester: John Wiley [distributor],|cc2010}, author={Roger Narayan, Paolo Colombo} }
 @book{narayan_kumta_wagner, title={Advances in biomedical and biomimetic materials: A collection of papers presented at the 2008 Materials Science and Technology Conference}, ISBN={9780470408476}, publisher={Hoboken, N.J.: J. Wiley & Sons}, author={Narayan, R. J. and Kumta, P. N. and Wagner, W. R.} }
 @misc{skoog_elam_narayan, title={Atomic layer deposition: Medical and biological applications}, volume={58}, number={2}, journal={International Materials Reviews}, author={Skoog, S. A. and Elam, J. W. and Narayan, R. J.}, pages={113–129} }
 @article{balani_verma_agarwal_narayan, title={BIOSURFACES a materials science and engineering perspective PREFACE}, journal={Biosurfaces: A Materials Science and Engineering Perspective}, author={Balani, K. and Verma, V. and Agarwal, A. and Narayan, R.}, pages={XVII-} }
 @misc{wei_sethuraman_jin_monteiro-riviere_narayan, title={Biological properties of carbon nanotubes}, volume={7}, number={4-5}, journal={Journal of Nanoscience and Nanotechnology}, author={Wei, W. and Sethuraman, A. and Jin, C. and Monteiro-Riviere, N. A. and Narayan, R. J.}, pages={1284–1297} }
 @book{roger narayan, title={Biomedical materials}, publisher={New York: Springer}, author={Roger Narayan, editor} }
 @inbook{chang_narayan_saryor_jou_wu_vetter_gong_wang_brown_yuill, title={DecIdUouS: decentralized source identification for network-based intrusions}, booktitle={Integrated network management VI: Distributed management for the networked millennium}, publisher={Piscataway, NJ: IEEE Pub.}, author={Chang, H. Y. and Narayan, R. and Saryor, C. and Jou, P. and Wu, S. F. and Vetter, B. M. and Gong, F. and Wang, X. and Brown, M. and Yuill, J. J.}, editor={M. Sloman, S. Mazumdar and Lupu, E.Editors}, pages={701–714} }
 @book{diamond-based materials for biomedical applications, publisher={Oxford: Woodhead Publishing} }
 @misc{aggarwal_narayan_xiao_geohegan, title={Fabrication of Ag-tetracyanoquinodimethane nanostructures using ink-jet printing/vapor-solid chemical reaction process}, volume={26}, number={6}, journal={Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures}, author={Aggarwal, R. and Narayan, R. J. and Xiao, K. and Geohegan, D. B.}, pages={L48–52} }
 @article{narayan_bhaumik, title={Fundamental discovery of new phases and direct conversion of carbon into diamond and hBN into cBN and properties}, volume={47A}, number={4}, journal={Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science}, author={Narayan, J. and Bhaumik, A.}, pages={1481–1498} }
 @misc{jaipan_nguyen_narayan, title={Gelatin-based hydrogels for biomedical applications}, volume={7}, number={3}, journal={MRS Communications}, author={Jaipan, P. and Nguyen, A. and Narayan, R. J.}, pages={416–426} }
 @article{petrochenko_zhang_wildt_betz_goering_wang_sun_narayan, title={In vitro cytotoxicity of rare earth oxide nanoparticles for imaging applications}, volume={9}, number={5}, journal={International Journal of Applied Ceramic Technology}, author={Petrochenko, P. E. and Zhang, Q. and Wildt, B. and Betz, M. W. and Goering, P. L. and Wang, H. R. and Sun, T. and Narayan, R. J.}, pages={881–892} }
 @misc{gittard_narayan, title={Laser direct writing of micro- and nano-scale medical devices}, volume={7}, number={3}, journal={Expert Review of Medical Devices}, author={Gittard, S. D. and Narayan, R.}, pages={343–356} }
 @misc{narayan_boehm_sumant, title={Medical applications of diamond particles & surfaces}, volume={14}, number={4}, journal={Materials Today}, author={Narayan, R. J. and Boehm, R. D. and Sumant, A. V.}, pages={154–163} }
 @misc{khanna_ong_oral_narayan, title={Progress in wear resistant materials for total hip arthroplasty}, volume={7}, number={7}, journal={Coatings}, author={Khanna, R. and Ong, J. L. and Oral, E. and Narayan, R. J.} }
 @book{rapid prototyping of biomaterials: principles and applications, publisher={Cambridge: Woodhead Publishing} }
 @article{narayan, title={Recent advances in prostheses}, volume={164}, number={4}, journal={Advanced Materials & Processes}, author={Narayan, R.}, pages={64} }
 @article{skoog_narayan, title={Stereolithography in medical device fabrication}, volume={171}, number={3}, journal={Advanced Materials & Processes}, author={Skoog, S. A. and Narayan, R. J.}, pages={32–34} }
 @article{narayan, title={The crucial role of nanomaterials innovation}, volume={166}, number={1}, journal={Advanced Materials & Processes}, author={Narayan, R.}, pages={64–64} }
 @misc{gittard_ovsianikov_chichkov_doraiswamy_narayan, title={Two-photon polymerization of microneedles for transdermal drug delivery}, volume={7}, number={4}, journal={Expert Opinion on Drug Delivery}, author={Gittard, S. D. and Ovsianikov, A. and Chichkov, B. N. and Doraiswamy, A. and Narayan, R. J.}, pages={513–533} }