Double layer thermoplastic polyurethane-gelatin electrospun wound dressings for biomedical applications

Abstract

Electrospinning is the technique to produce nano or micro scale fibers. Since this technique offers high surface area to volume ratio and porous structure, the dressing mimics the extracellular matrix (ECM). This technique gives the opportunity to use synthetic and natural polymers, active agents or essential oils, for that reasons it is a commonly preferred technique to produce wound dressings. Besides, to be able to add more features to the wound dressings double layer electrospun dressings have been made recently. Therefore, top layer which basicly includes synthetic polymers and active agents mimicks the epidermis layer, wheras sublayer with natural polymers and active agents mimicks the dermis layer of the skin. In this study, double layer nanofiber mats were produced by electrospinning technique. Each layer had a St. John's Wort oil (Hypericum perforatum oil) to provide a curative effect on the wound healing process. Top layer, which includes thermoplastic polyurethane (TPU) and Hypericum Perforatum Oil, was elastic, prevented water and pathogen transition and gave mechanical strength to the electrospun mat. On the other hand, the bottom layer which basically includes cold water fish gelatine and Hypericum Perforatum Oil firstly aimed to repair by being a source of collagen. With these properties the top layer and bottom layer mimic the epidermis and dermis layers of the skin, respectively. Besides, plasma treatment was applied as a surface activation technique for the TPU electrospun mat to have better adhesion to hydrophilic gelatin electrospun layer. By this way, better packing was obtained between the layers. Morphological and chemical characterization, water vapor transmission rate, absorption tests and antibacterial property test were done to the dressings. According to the result, a homogenous fiber structure was obtained. The Sample 2 showed antibacterial property and suggested for moderate to highly exudative wounds. On the other hand, Sample 3 which was a plasma treated sample also had homogenous, bead free fiber structure, showed antibacterial activity and suggested for moderately exudative wounds, but it had lower active agent release during the test period due to better packing between the layers with plasma treatment. Sample 3 had lower active agent release during the test period. Therefore the sample could be suggested for long term remedies. Overall results indicated that obtained nanofiber dressings can be a good candidate as a wound dressing material.