Silver functionalized chitosan composite hydrogel with sustained silver release and enhanced antibacterial properties promotes healing of infected wounds.

Bacterial infections during wound healing often cause inflammation, which delays the healing process. Therefore, innovative wound dressings are urgently needed to inhibit bacterial infections and promote healing. This study proposes an Ag-functionalized chitosan hydrogel dressing, formed via a Schiff-base reaction between alkynyl Ag substituted chitosan (Ag-CS) and octafunctionalized polyhedral oligomeric silsesquioxane with benzaldehyde-terminated polyethylene glycol (POSS-PEG-CHO), to address the issue of bacterial infection in wounds. The hydrogel demonstrated excellent injectability and self-healing properties. AgNPs and alkynyl Ag, produced by the reducing effect of chitosan and the reversible reaction of alkynyl Ag, delay the release of Ag. Furthermore, the hydrogel exhibits a broad-spectrum antibacterial effect and effectively inhibits bacterial biofilm formation. The release of Ag lasts for 7 days, ensuring sustainable antibacterial properties. In a mouse infected wound model, the composite hydrogel significantly accelerated wound healing. By the eighth day, the wound healing rate reached 99 %, whereas the control group achieved only 91 %. Histological and immunofluorescence staining results indicated that hydrogel-treated wounds had faster re-epithelialization, collagen deposition, and angiogenesis, with reduced inflammation. In conclusion, the Ag-functionalized chitosan hydrogel, with sustained Ag release and enhanced antibacterial properties, shows great potential as a wound dressing for promoting the healing of infected wounds.