Biodegradable trimethyl chitosan nanofiber mats as bioabsorbable dressings for wound closure and healing

Background Quaternary chitosan based fibers have emerged as promising biomaterials for tissue engineering, wound healing and hygiene related textiles, but their in vivo application is restricted by the lack of biodegradability of the synthetic polymers used as co-spinning agents. Herein, we report fully biodegradable chitosan/N,N,N-trimethyl chitosan (TMC) nanofibers prepared via electrospinning, when using poly(ethylene glycol) as sacrificial additive, as potential bioabsorbable wound dressings. Methods The composition and morphology of the fiber mats was confirmed by Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance, thermogravimetric analysis, wide angle X-ray diffraction, polarized optical microscopy and scanning electron microscopy. Their properties required for in vivo application, such as behavior in moisture media (dynamic vapor sorption, swelling and enzymatic degradation tests), muco- and bio-adhesive character, mechanical properties and antimicrobial activity were measured. The in vitro biocompatibility on normal human dermal fibroblasts was investigated in line with standards for biomedical devices and in vivo acute toxicity and biocompatibility was assessed by monitoring hematological, biochemical and immunological profile on Wistar rats. Wound closure and healing was studied on burn wound healing models in rats. Results The combination of chitosan with its TMC derivative into nanofibers enabled high swelling ability and fluid exchange, biodegradability rate controlled by the TMC content and pH of media, muco- and bioadhesive character, mechanical properties similar to skin tissue, strong antimicrobial activity against relevant pathogens and in vitro and in vivo biocompatibility. Moreover, their subcutaneous implantation in rats revealed in vivo biodegradation and lack of toxicity. As a proof of concept, the fiber mats application on burn wound healing models in rats showed wound closure and active healing, with fully restoration of epithelia. Conclusions The use of poly(ethylene glycol) with double role, electrospinning and sacrificial additive, is a straight pathway to the obtaining of chitosan/TMC nanofibers. The combination of chitosan with its N,N,N-trimethyl chitosan derivative into nanofiber mats provide a bioabsorbable bandage which favors rapid wound closure and fully restoration of the skin tissue.