Antibacterial and hemostatic composite gauze of N,O-carboxymethyl chitosan/oxidized regenerated cellulose

Viscose gauze was oxidized with NO2/CCl4 to prepare Oxidized Regenerated Cellulose (ORC). Then, ORC was modified by the water-soluble chitosan derivative N,O-carboxymethyl chitosan (N,O-CS). This was synthesized via the reaction of chitosan with chloroacetic acid as the etherification agent in the presence of alkaline. It was prepared by introducing carboxymethyl groups onto the N and O-positions of the chitosan and the substituting degree (DS) of N,O-CS reached 1.68. Composite gauzes with a 2-8 w/v% N,O-CS content were prepared in water solution. Composite gauzes could still maintain their original morphological form and have excellent water-solubility. The formation of an amide bond between the carboxyl group of ORC and the amino group of N,O-CS was confirmed by FT-IR and elemental analysis. To study the influence of carboxymethyl groups on chitosan, the thermal stability and crystallinity of N,O-CS were tested by XRD and TG. Based on SEM images, N,O-CS tended to be adsorbed on the surface of ORC fiber. The antibacterial performance of N,O-CS/ORC gauzes was enhanced with the increases of N,O-CS content. Moreover, N,O-CS/ORC gauzes showed excellent bactericidal activity against both Gram-positive and Gram-negative bacteria. The hemostatic evaluation indicated that the N,O-CS/ORC composite gauzes in rabbit livers had dramatic hemostatic efficacy. The prepared composite gauzes were anticipated to be an optimal material in preventing post-operative adhesion.