Investigation of lysine acrylate containing poly(N-isopropylacrylamide) hydrogels as wound dressings in normal and infected wounds.

The design of materials for cutaneous wound dressings has advanced from passive wound covers to bioactive materials that promote skin regeneration and prevent infection. Crosslinked poly(N-isopropylacrylamide) (PNIPAAm)-based hydrogels have been investigated for a number of biomedical applications. While these materials can be used for drug delivery, limited cell interactions restrict their biological activity. In this article, acryoyl-lysine (A-Lys) was incorporated into poly(ethylene glycol) crosslinked PNIPAAm to enhance biological activity. A-Lys could be incorporated into the hydrogels to improve cellular interaction in vitro, while maintaining swelling properties and thermoresponsive behavior. Polyhexamethylene biguanide, an antimicrobial agent, could be encapsulated and released from the hydrogels and resulted in decreased bacteria counts within 2 hours. Two in vivo animal wound models were used to evaluate the hydrogel wound dressing. First, application of the hydrogels to a rodent cutaneous wound healing model resulted in significant increase in healing rate when compared with controls. Moreover, the hydrogels were also able to decrease bacteria levels in an infected wound model. These results suggest that PNIPAAm hydrogels containing A-Lys are promising wound dressings due to their ability to promote healing and deliver active antimicrobial drugs to inhibit infection.