"Smart" polymer enhances the efficacy of topical antimicrobial agents.

The delivery of antimicrobial agents to surface wounds has been shown to be of central importance to the wound healing process. In this work, we prepared film forming wound care formulations containing 3 polymers (FTP) that provide broad-spectrum antimicrobial protection for prolonged periods. FTP formulations comprises of a smart gel matrix comprising of pH-degradable and temperature responsive polyacetals (smart polymer) which allow for the FTP films to be hydrophobic at room temperature, preventing accidental rubbing off, and hydrophilic at lower temperatures, allowing for easy removal. Two FTP smart-antimicrobial films were evaluated in this work: FTP-AgSD (Silver sulfadiazine actives), and FTP-NP (Neosporin actives). The in vitro and ex vivo antimicrobial efficacy studies show that FTP-AgSD films are significantly more effective for longer durations against Staphylococcus aureus (3 days), Candida albicans (9 days) and Pseudomonas aeruginosa (4 days) when compared to the cream formulations containing antimicrobials. FTP-NP films showed significantly improved antimicrobial activity for a minimum of 3 days for all pathogens tested. Moreover, when tested ex vivo in porcine skin, FTP-AgSD and FTP-NP showed average improvements of 0.89 log and 1.66 log respectively over standard cream counterparts. Dermal toxicity studies were carried out in a rat skin excision model which showed a similar wound healing pattern to that in rats treated with standard cream formulations as represented by reduction in wound size, and increase in wound healing markers.