Improving Healing Performance of Wound Dressing: Electrospinning of Chitosan-based, Cellulose-based Fibers and their Blends

Abstract

The overall goal of this research is to respond to the need for conducting fundamental research to develop and evaluate highly absorbable inexpensive chitosan/cellulose based structures with high surface area for wound dressings. The goal is achieved by forming and evaluating composite structures. The structures consist mainly of two components. The first is cellulose based hydrogelled materials or nanofiber layer capable of absorbing at least 10 times of its weight of wound discharge liquids. The hydrogel fibrous structures are formed by grafting with a vinyl monomer to impart hydrophilic functional groups. The second is a nonwoven layer of nanofibers formed by electrospinning the nanofibers from chitosan-based solutions because chitosan is an excellent antimicrobial polymer. This research is focused on forming electrospun nonwoven layer from chitosan-based, cellulose-based polymer solution and their blends. Since chitosan cannot be electrospun, a chitosan derivative (iminochitosan) was synthesized and electrospinning trials of its solution were conducted. The correct blend of electrospinning parameters (polymer concentration in the solution, solution feed rate, and electrical field strength) that provide fiber formation was revealed and nanofibers webs were formed over woven gauze structures. Contact kill performance of the structures against range of microbes was carried out using the disc diffusion method. The results indicated that the developed nanofiber webs exhibited an excellent antimicrobial behavior. It was observed that the inhibition zone increases with increase in covering power of the iminochitosan layer and basis weight and decrease in fiber diameter. Also the fiber forming tendency increases with the decrease in the extrusion rate. Relationships describing the antimicrobial behavior of iminochitosan layer in terms of structural parameters (covering power, diameter, and basis weight) were developed. Additionally, structure parameters were related to electrospinning processing parameters (solution concentration, extrusion rate, and electrical field). To increase the absorbency of proposed wound dressing, a cellulose acetate liquid crystal fiberwebs were produced using electrospinning technology from high concentration solutions of cellulose acetate in Trifluoroacetic acid. The average absorbency of cellulose acetate fiberwebs was found to be 10-15 times compared to their original weight. To create antimicrobial high absorbent nanofiber layer, iminochitosan was blended with cellulose acetate. Different trials were carried out using electrospinning solutions from cellulose acetate and iminochitosan blend. The absorbency and antimicrobial properties of the structures were investigated. Electrospinning trials were conducted to form core/sheath fibers with iminochitosan as a sheath and cellulose acetate as a core. This was achieved by using two separate solutions and modified extrusion system. Core/sheath structure is believed to provide effective wound dressing in that iminochitosan acts as an antimicrobial while the cellulose acetate provides absorbency and strength.