Silver Nanoparticle-Coated Polyhydroxyalkanoate Based Electrospun Fibers for Wound Dressing Applications.

Wound dressings are high performance and high value products which can improve the regeneration of damaged skin. In these products, bioresorption and biocompatibility play a key role. The aim of this study is to provide progress in this area via nanofabrication and antimicrobial natural materials. Polyhydroxyalkanoates (PHAs) are a bio-based family of polymers that possess high biocompatibility and skin regenerative properties. In this study, a blend of poly(3-hydroxybutyrate) (P(3HB)) and poly(3-hydroxyoctanoate-co-3-hydroxy decanoate) (P(3HO-co-3HD)) was electrospun into P(3HB))/P(3HO-co-3HD) nanofibers to obtain materials with a high surface area and good handling performance. The nanofibers were then modified with silver nanoparticles (AgNPs) via the dip-coating method. The silver-containing nanofiber meshes showed good cytocompatibility and interesting immunomodulatory properties in vitro, together with the capability of stimulating the human beta defensin 2 and cytokeratin expression in human keratinocytes (HaCaT cells), which makes them promising materials for wound dressing applications.

A Novel Carbon Nanofiber Precursor: Poly(acrylonitrile-co-vinylacetate-co-itaconic acid) Terpolymer.

This study aimed to produce poly(acrylonitrile-co-vinylacetate-co-itaconic acid) (poly(AN-co-VAc-co-IA)) terpolymer as a carbon nanofiber precursor. In this respect, terpolymer samples with different IA amounts were synthesized by free radical polymerization. Produced terpolymer samples were electrospun in order to obtain nanofibers which were then converted to carbon nanofibers. Obtained electrospun nanofibers were oxidized at different temperatures between 200-325 °C. After the oxidation process, carbonization process was applied at 1100 °C in the presence of N2. Viscosity and molecular weight distribution of produced samples were measured with ubbelohde viscosimeter and gel permeation chromatography (GPC), respectively. Thermal features of the ter-polymer samples were analyzed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Spectroscopic characterization of terpolymer samples, oxidized and carbonized nanofibers were performed by Fourier transform infrared-attenuated total reflectance (FTIR-ATR). Original electrospun nanofibers, oxidized and carbonized nanofibers were investigated morphologically by scanning electron microscope (SEM). Inclusion of IA had considerable effect on terpolymer properties and electrospun nanofibers. Moreover, it was proven that oxidation temperature was a crucial parameter for carbon nanofiber production from terpolymer. Both morphology and color of the produced nanofiber mats changed when carbonization process was accomplished. It was observed that poly(AN-co-VAc-co-IA) terpolymer has lower initiation temperature when compared to poly(AN-co-VAc) and poly(AN-co-IA) copolymers, giving the opportunity to obtain carbon nanofibers easier, and poly(AN-co-VAc-co-IA) terpolymer can be used as an effective precursor for carbon nanofiber production.