Novel Temperature Responsive Films Impregnated with Silver Nano Particles (Ag-NPs) as Potential Dressings for Wounds

Silver nanoparticles have attracted wide interest in medicine on account of their antibacterial activity. We report in this paper, the antibacterial activity and biocompatibility of a temperature responsive topical film fabricated from pullulan-g-pNIPAM and impregnated with two different concentrations (15 ppm and 30 ppm) of silver nanoparticles (Ag-NPs). The release of silver from the film under the influence of temperature above the LCST has been studied and the in vitro release profile of the films has been compared with a marketed silver nano formulation, 'Meganano gel'. The release of silver from the films has a distinctive profile characterized by a sustained release over a period of 48 hrs, which is comparable to the marketed formulation. The films exhibit excellent swelling properties, making them ideal materials for absorption of exudates from wounds. The antibacterial activity of the films has been established at physiological temperature against gram-positive S. aureus and gram-negative E. coli and compared with the marketed formulation. A cytotoxicity evaluation on HeK293 cells has demonstrated their biocompatibility. The nanocomposite films are thus a new therapeutic device for management of non-healing wounds being constructed from temperature responsive polymers that release Ag-NPs when the temperature of the wound exudate is slightly higher than normal.