Development of polyurethane based foam dressing impregnated with silver nanoparticles and asiaticoside for dermal wound treatment

Abstract

This study was an innovation of polyurethane foam dressing containing silver nanoparticles and asiaticoside that aimed to treat dermal wounds. It consists of three essential properties; the natural polyols containing foam dressing could absorb exudate and maintain moisture in the wound bed, the silver could prevent and kill bacteria, the asiaticoside could accelerate wound healing. The foam dressing was produced and 2% of hydrophilic natural polyols of various types added. The characteristics were evaluated. Hydroxypropyl methylcellulose (HPMC), chitosan low MW (CLMW) and sodium alginate (Alg) were selected according to their high absorption capacity, low dehydration, good mechanical strength and low degradation. Then, the foams were varied in polymer concentrations of 2-12%, and the physical and compatible properties were evaluated. The small pore size might increase water absorption while the larger pore size might increase water dehydration. The higher concentration of natural polyols retained hydration and increased the absorption capacity and compressive strength; however, this decreased the strength and percentage of elongation. Foam without natural polyols (Bl), foam with natural polyols in 4 and 6 percent concentrations; HPMC (H4, H6), CLMW (C4, C6) and Alg (A4, A6) were selected to be impregnated with silver nanoparticles and evaluated for the releasing profiles. High concentrations of silver and natural polyols affected a greater silver release. Foam with 1.0 mg/cm2 of silver including Bl-1Ag, H6-1Ag, C6-1Ag, and A6-1Ag were chosen to add 5% of asiaticoside (AS), and then the asiaticoside releasing test was determined. Bl-1Ag-AS and A6-1Ag-AS showed a rapid release of this compound, respectively. The gamma radiation as well as storage at an accelerated condition including high temperature and humidity could degrade the asiaticoside, but not affecting the silver nanoparticles. All formulations showed comparable large clear inhibition zone and also showed non-cytotoxicity in the fibroblasts by MTT assay. In accordance with the high releasing of two active compounds, A6-1Ag-AS was selected to be used for the animal and clinical studies. The percentage of the wound closure and histological data supported that the A6-1Ag-AS could accelerate wound healing in deep partial thickness wound of a porcine model. They were also no undesirable effects in the rabbit model and in healthy volunteers. Data from trauma patients showed the number of days of the wound closure of the A6-1Ag-AS treated wounds was decreased compared with a standard commercial dressing. The percentage of the re-epithelialization of the study group was higher than the comparative group on Days 6 and 8. All patients did not experience any adverse skin reactions. From characterization in vitro studies to wound healing in vivo studies, the polyurethane foam dressing with silver nanoparticles and asiaticoside showed satisfactory results. It might become a good candidate for wound dressing in the future.