Electrospun Methacrylated Gelatin/Poly(L-Lactic Acid) Nanofibrous Hydrogel Scaffolds for Potential Wound Dressing Application

Electrospun nanofiber mats have attracted intense attention as advanced wound dressing materials. The objective of this study was to fabricate methacrylated gelatin (MeGel)/poly(L-lactic acid) (PLLA) hybrid nanofiber mats with an extracellular matrix (ECM) mimicking nanofibrous structure and hydrogel-like properties for potential use as wound dressing materials. MeGel was first synthesized via the methacryloyl substitution of gelatin (Gel), a series of MeGel and PLLA blends with various mass ratios were electrospun into nanofiber mats, and a UV crosslinking process was subsequently utilized to stabilize the MeGel components in the nanofibers. All the as-crosslinked nanofiber mats exhibited smooth and bead-free fiber morphologies. The MeGel-containing and crosslinked nanofiber mats presented significantly improved hydrophilic properties (water contact angle = 0°; 100% wettability) compared to the pure PLLA nanofiber mats (~127°). The swelling ratio of crosslinked nanofiber mats notably increased with the increase of MeGel (143.6 ± 7.4% for PLLA mats vs. 875.0 ± 17.1% for crosslinked 1:1 MeGel/PLLA mats vs. 1135.2 ± 16.0% for crosslinked MeGel mats). The UV crosslinking process was demonstrated to significantly improve the structural stability and mechanical properties of MeGel/PLLA nanofiber mats. The Young’s modulus and ultimate strength of the crosslinked nanofiber mats were demonstrated to obviously decrease when more MeGel was introduced in both dry and wet conditions. The biological tests showed that all the crosslinked nanofiber mats presented great biocompatibility, but the crosslinked nanofiber mats with more MeGel were able to notably promote the attachment, growth, and proliferation of human dermal fibroblasts. Overall, this study demonstrates that our MeGel/PLLA blend nanofiber mats are attractive candidates for wound dressing material research and application.

Microstructure and Biological Properties of Electrospun In Situ Polymerization of Polycaprolactone-Graft-Polyacrylic Acid Nanofibers and Its Composite Nanofiber Dressings

In this study, polycaprolactone (PCL)- and poly(acrylic acid) (PAA)-based electrospun nanofibers were prepared for the carriers of antimicrobials and designed composite nanofiber mats for chronic wound care. The PCL- and PAA-based electrospun nanofibers were prepared through in situ polymerization starting from PCL and acrylic acid (AA). Different amounts of AA were introduced to improve the hydrophilicity of the PCL electrospun nanofibers. A compatibilizer and a photoinitiator were then added to the electrospinning solution to form a grafted structure composed of PCL and PAA (PCL-g-PAA). The grafted PAA was mainly located on the surface of a PCL nanofiber. The optimization of the composition of PCL, AA, compatibilizer, and photoinitiator was studied, and the PCL-g-PAA electrospun nanofibers were characterized through scanning electron microscopy and 1H-NMR spectroscopy. Results showed that the addition of AA to PCL improved the hydrophilicity of the electrospun PCL nanofibers, and a PCL/AA ratio of 80/20 presented the best composition and had smooth nanofiber morphology. Moreover, poly[2 -(tert-butylaminoethyl) methacrylate]-grafted graphene oxide nanosheets (GO-g-PTA) functioned as an antimicrobial agent and was used as filler for PCL-g-PAA nanofibers in the preparation of composite nanofiber mats, which exerted synergistic effects promoted by the antibacterial properties of GO-g-PTA and the hydrophilicity of PCL-g-PAA electrospun nanofibers. Thus, the composite nanofiber mats had antibacterial properties and absorbed body fluids in the wound healing process, thereby promoting cell proliferation. The biodegradation of the PCL-g-PAA electrospun nanofibers also demonstrated an encouraging result of three-fold weight reduction compared to the neat PCL nanofiber. Our findings may serve as guidelines for the fabrication of electrospun nanofiber composites that can be used mats for chronic wound care.

Robust Nanofiber Mats Exfoliated From Tussah Silk for Potential Biomedical Applications

Nanofibers as elements for bioscaffolds are pushing the development of tissue engineering. In this study, tussah silk was mechanically disintegrated into nanofibers dispersed in aqueous solution which was cast to generate tussah silk fibroin (TSF) nanofiber mats. The effect of treatment time on the morphology, structure, and mechanical properties of nanofiber mats was examined. SEM indicated decreasing diameter of the nanofiber with shearing time, and the diameter of the nanofiber was 139.7 nm after 30 min treatment. These nanofiber mats exhibited excellent mechanical properties; the breaking strength increased from 26.31 to 72.68 MPa with the decrease of fiber diameter from 196.5 to 139.7 nm. The particulate debris was observed on protease XIV degraded nanofiber mats, and the weight loss was greater than 10% after 30 days in vitro degradation. The cell compatibility experiment confirmed adhesion and spreading of NIH-3T3 cells and enhanced cell proliferation on TSF nanofiber mats compared to that on Bombyx mori silk nanofiber mats. In conclusion, results indicate that TSF nanofiber mats prepared in this study are mechanically robust, slow biodegradable, and biocompatible materials, and have promising application in regenerative medicine.

Magnetic Carbon Nanofiber Mats for Prospective Single Photon Avalanche Diode (SPAD) Sensing Applications

Electrospinning enables simple and cost-effective production of magnetic nanofibers by adding nanoparticles to a polymer solution. In order to increase the electrical conductivity of such nanofibers, the carbonization process is crucial. In this study, the chemical and morphological properties of magnetic nanofiber mats prepared from polyacrylonitrile (PAN)/magnetite were investigated. In our previous studies, PAN/magnetite nanofiber mats were carbonized at 500 °C, 600 °C, and 800 °C. Here, PAN/magnetite nanofiber mats were carbonized at 1000 °C. The surface morphology of these PAN/magnetite nanofiber mats is not significantly different from nanofiber mats thermally treated at 800 °C and have remained relatively flexible at 1000 °C, which can be advantageous for various application fields. The addition of nanoparticles increased the average fiber diameter compared to pure PAN nanofiber mats and improved the dimensional stability during thermal processes. The high conductivity, the high magnetization properties, as well as shielding against electromagnetic interference of such carbonized nanofibers can be proposed for use in single photon avalanche diode (SPAD), where these properties are advantageous.