In Situ Formation of Silver Nanoparticles-Containing Gallic Acid-Conjugated Chitosan Hydrogels as Antimicrobial Tissue Adhesive Materials

Antimicrobial hydrogels have attracted considerable attention for wound treatment due to the major clinical challenges of bacterial infections, which lead to delayed tissue regeneration and chronic inflammation. In addition, the strong adhesion of antimicrobial hydrogels to tissue surfaces is essential because wounds are generally moist, topographically irregular, and continuously exposed to various biological molecules. In this study, we developed in situ formed silver nanoparticle (Ag NP)-incorporated gallic acid-conjugated chitosan (CHI-G) hydrogels as bio-inspired antimicrobial and tissue adhesive materials. Ag/CHI-G hydrogels were successfully formed by the simultaneous reduction in Ag⁺ ions with a stable dispersion of Ag NPs. No additional reduction agents or crosslinkers were required to prepare the Ag/CHI-G hydrogels. In addition, the elastic moduli of the Ag/CHI-G hydrogels increased significantly with increasing concentrations of both AgNO₃ and CHI-G. Furthermore, the hydrogels exhibited excellent adhesion to the porcine intestinal tissue surfaces. The adhesive Ag/CHI-G hydrogels showed an inhibition of both <i>Escherichia coli</i> and <i>Staphylococcus aureus</i> with no significant cytotoxicity against NIH3T3 and CCD-18Co fibroblasts. Thus, in situ formed Ag/CHI-G hydrogels with adhesive, biocompatible, and antimicrobial properties are expected to be useful for versatile biomedical applications, such as drug delivery depots, tissue engineering hydrogels, and wound dressing materials.