Novel Atmospheric Plasma Enhanced Nanofiber/Gauze Composite Wound Dressings

Traditional textile-based wound dressings are cost effective and highly absorbent but used alone, fail to provide optimal wound healing conditions (hemostasis, non-adherence, maintenance of a moist wound bed, etc.). Recently, many advanced wound dressings have been developed to provide enhanced functionalities and help to maintain an appropriate healing environment around wounds, but also led to higher cost and difficulty in handling. Another disadvantage of using modern wound dressing is that these dressings can either act as primary or secondary wound dressing (e.g. hydrocolloids, hydrogels, calcium alginate, transparent films, foam, hydrofibers, etc.). Electrospun nanofiber dressings have demonstrated the potential to revolutionize wound care by providing significantly enhanced moisture management, barrier properties, and bioactivity. However, nanofiber webs are inherently weak and difficult to handle. Deposition of electrospun nanofiber coatings on a traditional textile bandages addresses the need for structural support, but faces challenges of delamination due to compliance mismatch or poor adhesion. The goal of this research is to create biopolymer based nanofiber/gauze composite bandages that combine the desirable properties of each component, and to characterize the physical and mechanical properties of these materials in order to predict the performance of these novel materials for wound care applications.;In this research work, following tasks have been carried out:;i) Selection of appropriate substrate and nanofiber combinations: Substrate material for the nanofiber coatings was chosen from existing commercially available 100% cotton gauze. Two bio-polymers, chitosan and silk fibroin (SF) were selected for electrospinning nanofiber web on to the cotton substrate in order to make composite wound dressing. Trifluoroacetic acid was selected as solvent to prepare electrospinning solution. In these composite bandages, chitosan/silk fibroin can act as primary wound dressing whereas cotton substrate can act as backing material and secondary wound dressing.;ii) Controlled deposition of nanofiber mat onto woven fabric substrate: Electrospinning of chitosan and SF were carried out on to 100% cotton substrate in order to prepare composite bandages. Polymer solution concentration, electrospinning voltage, and deposition areal density were varied to establish the relationship of processing-structure-filtration efficiency for electrospun fiber mats. Optimum concentration of polymer in solvent was finalized based on SEM images, sturdiness of nanofibers, and its production rate.;iii) Improving interfacial adhesion between nanofiber mat and cotton substrate by plasma pretreatment of substrate fabric and plasma-post treatment of composite bandage: Adhesion between nanofibers and substrate was studied using two test methods, quantitative and qualitative. The peel test which was quantitative test showed that plasma treatment of the substrate increased the adhesion between nanofiber layers and gauze substrate. This force was further increased when composite bandages were given plasma pre-treatment to substrate as well as post-treatment to composite bandages. To assess the improved adhesion between nanofiber layer and substrate, gelbo flex test was employed in which the composite bandages were subjected to 1000 cycles of twisting and flexing. Atmospheric plasma pretreatment of the gauze fabric prior to electrospinning and post treatment of composite bandages significantly reduced degradation of the nanofiber layer due to repetitive flexing. To understand the mechanism of improved adhesion between nanofiber layer and cotton substrate, surface elemental analysis of plasma treated/untreated cotton substrate and nanofiber layer were carried out.;iv) Characterization of nanofiber/cotton substrate composite bandage: Composite bandages were characterized for maintaining moist wound healing environment. These characterization techniques included moisture vapor transmission rate, air permeability, and absorbency. Antibacterial properties of chitosan based nanofiber/cotton substrate wound dressing were analyzed. To study the effect of atmospheric pressure plasma on storage modulus, crystallinity, glass transition temperature, and cell viability of chitosan and silk nanofiber, characterization techniques such as dynamic mechanical analysis, wide angle X-ray diffraction, and differential scanning calorimentry were carried out.