Chito-oligosaccharide-reinforced thermally cross-linked fish skin gelatin films with silver nanoparticles: Enhanced properties and accelerated wound healing

Fish skin gelatin (FG) has been widely used in medical dressings owing to its excellent biocompatibility. Nevertheless, conventional gelatin-based dressings usually rely on chemical cross-linking agents to enhance stability, which inevitably brings potential risks of toxic residues. To address this issue, a green thermal cross-linking strategy was employed to covalently stabilize FG films, providing a safer, more economical, and environmentally friendly route without chemical cross-linkers. Synergistic incorporation of chito-oligosaccharide (COS) and silver nanoparticles (AgNPs) significantly improved mechanical strength and antibacterial activity of the materials. Thermal cross-linking at 180 °C for 20 min endowed the FG film with optimal structural stability and mechanical properties. Notably, the thermally cross-linked FG/COS film with FG: COS mass ratio of 20:1 (FG/COS-5) achieved the best tensile performance. The final composite dressing (AgNPs@FG/COS-5) showed strong antibacterial activity against Escherichia coli and Staphylococcus aureus , while demonstrating low cytotoxicity and superior biocompatibility. In a rat wound healing model, AgNPs@FG/COS-5 significantly accelerated early-stage wound closure within 3 days, outperforming Tegaderm™ and FG dressings. These results demonstrate that the green thermal cross-linking strategy combined with rational component design endows composite dressing with enhanced stability, antibacterial activity, and rapid wound repair efficacy, suggesting its great promise for clinical tissue repair applications.