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In the past two decades, microneedles (MNs) patches as a promising platform have been extensively investigated for transdermal delivery of drug drugs, cells, and active substances and extraction of bio‐fluids. To realize painless, efficacious, and safe transdermal delivery, these MNs must penetrate the skin to the appropriate depth without breaking or bending. Therefore, effective prediction of mechanical properties such as skin penetration of microneedles is crucial for the material and structural design of MNs. In this article, a numerical simulation of the insertion process of the microneedle into various types of skin modeling is reported using the finite element method. The effective stress failure criterion has been coupled with the element deletion technique to predict the complete insertion process. The numerical results show a good agreement with the reported experimental data for the deformation and failure of the skin and the insertion force. [ABSTRACT FROM AUTHOR]

In recent years, transdermal drug delivery based on microneedles (MNs) technology has received extensive attention, which offers a safer and painless alternative to hypodermic needle injections. They can pierce the stratum corneum and deliver drugs to the epidermis and dermis‐structures of skin, showing prominent properties such as minimally invasiveness, bypassing first‐pass metabolism, and can be self‐administered. A range of materials has been used to fabricate MNs, such as silicon, metal, glass, and polymers. Among them, polymer MNs have gained increasing attention from pharmaceutical and cosmetic companies as one of the promising drug delivery methods. MN products have recently become available on the market, and some of them are under evaluation for efficacy and safety. This paper focuses on the current state of polymer MNs in drug transdermal delivery. The materials and methods for the fabrication of polymer MNs and their drug administration are described. The recent progress of polymer MNs for treatment of cancer, vaccine delivery, blood glucose regulation, androgenetic alopecia, obesity, tissue healing, myocardial infarction, and gout are reviewed. The challenges of MNs technology are summarized and the future development trend of MNs is also prospected. [ABSTRACT FROM AUTHOR]

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Hollow microcapsules, composed of pH responsive polyelectrolytes via a layer-by-layer (LBL) adsorption technique, were prepared. Linear or star-shaped poly(glycerol metha crylate)s (PGOHMAs) modified with 1,4-butanediamine and 1,2-ethanediamine (EDA) were synthesized and used as polycations. Poly(acrylic acid) was employed as polyanion and SiO2 (about 170 nm) as template. After LBL absorption, SiO2 cores were removed by HF treatment. The particle size and zeta potential were measured by dynamic light scattering, showing that the diameter of star-shaped amino-PGOHMA was larger than linear counterpart. The LBL assembly and core-etching process were evidenced by scanning electron microscope, transmission electron microscope, and energy dispersive spectrometer. The cytotoxicity experiments on human umbilical vein endothelial cells were carried out to evaluate the toxicity of LBL assembly. The star-shaped and EDA-modified PGOHMA exhibited better cell viability. The microcapsules were then used to load an anticancer drug, doxorubicin hydrochloride. High loading capacity (about 42%) and entrapment efficiency (84%) were obtained for star-shaped polymer-based microcapsules. The cumulative release rate was evaluated in vitro, showing faster release at an acidic condition compared to neutral pH. Confocal laser scanning microscopy evidenced the successful cellular uptake of DOX-loaded microparticles. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013. [ABSTRACT FROM AUTHOR]

Peripheral nerve injury often leads to the loss of neurological functions due to the slow regeneration rate and inefficient functional reconstruction. Current clinical treatments using nerve guidance conduits (NGCs) still face challenges in providing a biomimetic microenvironment to promote nerve repair. Herein, decellularized extracellular matrix (dECM) is obtained from porcine Achilles tendon and crosslinked with 3‐amino‐4‐methoxybenzoic acid grafted gelatin (PAMB‐G) to obtain conductive hydrogels. Then, a novel nerve guidance conduit is developed by assembling poly(vinyl alcohol) (PVA) conduit and conductive ECM@PAMB‐G hydrogel. This bioengineered ECM@PAMB‐G/PVA conduit demonstrated excellent cytocompatibility, electrical conductivity, mechanical properties, and biodegradability. In vitro experiments confirmed that the ECM@PAMB‐G hydrogel significantly promotes the proliferation and migration of PC12 cells and primary Schwann cells, as well as the growth of dorsal root ganglion (DRG) axons. Furthermore, in vivo studies in a rat sciatic nerve model exhibited improvements in axonal regeneration, Schwann cell migration, myelin sheath formation, and functional recovery mediated by the ECM@PAMB‐G/PVA conduit. This work demonstrates the synergistic effects of extracellular matrix and electrical cues in enhancing peripheral nerve regeneration. The ECM@PAMB‐G/PVA nerve guidance conduit shows potential as an alternative to autografts for supporting peripheral nerve reconstruction. [ABSTRACT FROM AUTHOR]

Nanoarray electrodes with highly capacitive materials and specific architectures are hopeful to realize advanced supercapacitor performance. The nickel foam (NF) supported hierarchical nanosheet array electrode is fabricated through a template route toward excellent capacitive supercapacitor. The hierarchical nanosheet array weaved with Ni(OH)2‐MnO2 nanowires provides multiple advantages for porous feature, high surface area, and fast charge transfer. The neighbored Ni(OH)2‐MnO2 supplies lattice fringes distortion as additional active sites as well as synergism, for improved capacitive performances. As expected, the Ni(OH)2‐MnO2/NF electrode manifests high specific capacitance of 14.7 F cm−2 at 2.5 mA cm−2 and good cyclic stability, making it hopeful for highly capacitive supercapacitor application. Hierarchical nanosheet array weaved by Ni(OH)2‐MnO2 nanowires is fabricated on nickel foam as integrated electrode for high‐capacity supercapacitor. The excellent performances are assigned to the structure benefits of hierarchical nanosheets, including high surface area, lattice fringes distortion, and shortened charge diffusion, as well as synergism between neighbored crystals hybridization. [ABSTRACT FROM AUTHOR]