@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} }
 @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{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{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{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{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{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{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{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} }
 @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{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} }
 @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} }