A pH-sensitive oxidized-dextran based double drug-loaded hydrogel with high antibacterial properties.

Delayed healing or non-healing of wounds caused by bacterial infection is still a difficult medical problem. Nowadays, the topical application of antibiotics is a common treatment for infections. However, subinhibitory concentrations or high dose of antibiotics leads to the antibacterial effect counterproductive. So it's necessary to put forward an on-demand drug delivery to solve this tough issue. In this paper, a pH-responsive hydrogel was prepared by oxidized dextran (Dex-CHO), sulfadiazine (SD) and tobramycin (TOB). The hydrogel was designed by the environment in the early immature stage of biofilm (pH 5.0). Schiff bases can release drugs in slightly acidic environment. The hydrogel showed injectable, pH-sensitive drug release, and great biocompatibility. Released SD and TOB exhibited a synergistic effect therefore the hydrogel showed high antibacterial activity. This study provides an easy and promising strategy to develop smart hydrogels that aim at topical administration of antibiotics and come up with a new treatment of local bacterial infections.