@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} }
 @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{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{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} }