An injectable adhesive antibacterial hydrogel wound dressing for infected skin wounds.

It's an exigent need for the improvement of novel antibacterial wound dressings with the increasing threats of drug resistance caused by excessive use of the antibiotics. In this work, an injectable, adhesive, hemostatic, biocompatible and bactericidal hydrogel wound dressing was fabricated. An injectable hydrogel can fill the irregular wound due to the characteristic of reversible sol-gel transition, whereas conventional dressings don't possess this ability. Oxidized alginate (ADA) and catechol-modified gelatin (Gel-Cat) were selected as the polymer backbones and they can crosslink in situ through double dynamic bonds, which were Schiff base and catechol-Fe coordinate bond; polydopamine decorated silver nanoparticles (PDA@Ag NPs) were also introduced into the hydrogel network. The double dynamic bonds endowed the hydrogel with injectable ability, shorter gelation time and enhanced mechanical property. And the aldehyde and catechol groups on the chains of ADA and Gel-Cat gave the hydrogel excellent adhesiveness. In addition, the PDA@Ag NPs in this system play two roles: one is bactericidal agent which can release from the hydrogel to kill the bacteria; the other is photothermal agent to convert 808 nm near-infrared light into heat to realize sterilization. In vitro study, the hydrogel displayed bactericidal ability against S. aureus and E. coli whether in photothermal antimicrobial test or agar diffusion test. In vivo test also testified that the hydrogel had a prominent therapeutic effect on infected wound through reducing inflammatory response and accelerating angiogenesis. Thus, we anticipate that our double dynamic bonds crosslinked hydrogel with PDA@Ag NPs as the antimicrobial agent can be a novel therapeutic way for infected wounds.