Tannic acid-based dual-network homogeneous hydrogel with antimicrobial and pro-healing properties for infected wound healing.

The clinical treatment of infected skin injuries caused by exogenous bacteria faces great challenges. Conventional therapeutic approaches are difficult to achieve synergistic effects of infection control and induction of skin regeneration. In this study, a novel tannic acid-based physically cross-linked double network hydrogel (PDH gel) was prepared on demand by covalent cross-linking of tannic acid (TA) with polyvinyl alcohol (PVA) and chelating ligand of TA with Fe. The homogeneity of the hydrogel was achieved by the action of glycol dispersant. With the anti-inflammatory and antioxidant properties of Fe and TA, this hydrogel exhibited excellent antibacterial properties by achieving 99.69% and 99.36% bacterial inhibition against E.coli and S. aureus, respectively. Moreover, the PDH gel exhibits good biocompatibility, stretchability (up to 200%) and skin-friendliness. After 14 days of PDH-1 gel implantation in a rat model infected by S. aureus, the wound healing rate was as high as 95.21%. PDH gel-1 showed more granulation tissue, more pronounced blood vessels, higher collagen fiber density and good collagen deposition, and its recovery effect was better than that of PSH gel and PDH gel-2 in vivo. Hence, this study provides a novel avenue for the design of future clinical infected wound healing dressings.