(360b) A Thermo-Responsive Antimicrobial Wound Dressing Hydrogel Based On a Cationic Betaine Ester

Serious wounding, typically incurred from armed conflicts as well as industrial accidents, can be a major contributor to the total loss of manpower and must be treated with specialized wound dressing materials. Despite its urgent demand, the state of art wound dressing technology today is still well behind, and the main challenge comes from the intrinsic complexity of wound healing process itself. Hydrogels have been studied and used as wound dressing materials for decades.This is largely due to the fact that the moist and occlusive environment provided by a hydrogel has been proven to significantly facilitate the wound healing process. An ideal hydrogel should combine multiple features including in situ gelation, antimicrobial activity, accelerating wound healing and long-term biocompatibility into one single design to address the different aspects of a dynamic wound healing process.

Herein, we report the synthesis and characterization of an ABA triblock copolymer as a thermo-responsive wound dressing hydrogel. The inner B block consists of a positively-charged betaine ester loaded with an antimicrobial drug, salicylate, as its counter ion (PCBAA-1-C2 SA). The B block is flanked by two outer A blocks of thermo-responsive PNIPAM. PNIPAM has a low critical solution temperature (LCST) close to human physiological temperature.Above its LCST, PNIPAM quickly turns from water soluble to insoluble in a very narrow temperature window, enabling the block copolymer solution to immediately form a hydrogel through physical crosslinking.The inner hydrophilic block PCBAA-1-C2 SA can release salicylate as a mild antimicrobial counter ion, while the cationic polymer backbone is designed to promote negatively charged fibronectin adsorption and thus, in turn, accelerate fibroblast cell adhesion and tissue regeneration. Furthermore, the PCBAA-1-C2 polymers used in this study have been experimentally shown to be able to hydrolyze to its ziwtterionic form in a well-controlled fashion.