Preparation of silane-dispersed graphene crosslinked vinyl carboxymethyl chitosan temperature-responsive hydrogel with antibacterial properties

We synthesized a temperature-sensitive antibacterial hydrogel, defined as NIPAM-CG/GM hydrogel. First, vinyl carboxymethyl chitosan (CG) was synthesized as a crosslinking carrier and silane dispersed graphene (GM) was synthesized as a reinforcer. Then, the N-isopropylacrylamide (NIPAM) monomer was free-radical polymerized with the vinyl groups of CG and GM to form a NIPAM-CG/GM hydrogel without any crosslinking agent. The influences of different hydrogel compositions on the microstructure, compressive properties, swelling, drug loading, and drug release properties of the hydrogels were discussed, and its temperature sensitivity was also demonstrated. The results showed that the lower critical solution temperature (LCST) and mechanical properties of the hydrogel could be adjusted by controlling the amount of CG and GM. Next, its biocompatibility was characterized, and its antibacterial performance was tested against Escherichia coli and Staphylococcus aureus . The antibacterial mechanism was explained by measuring the difference in the ion concentration outside the membrane and changes in the morphology of live/dead bacteria. NIPAM-CG/GM had a high drug loading and nearly complete drug release at a physiological temperature of 37 °C. Its moderate mechanical properties, excellent biocompatibility, and antibacterial effects give NIPAM-CG/GM great potential applications as a wound dressing.