Metal polyphenol double-network hydrogels based on chitosan/hyaluronic acid loaded with rosmarinic acid promote the healing and repair of infected wounds.

Bacterial infection and chronic inflammation after skin injury impede wound healing. Conventional treatments are limited by issues such as drug resistance and insufficient penetration, prompting the need for novel multifunctional dressings. In this study, a dual-network hydrogel (CS-RA/Zn2+-OHA) that incorporates chitosan grafted with rosmarinic acid (CS-RA), oxidized hyaluronic acid (OHA), and zinc ions (Zn2+) was developed. The hydrogel exhibits good mechanical properties, rapid self-healing within 5 min, and injectability because of dynamic Schiff base reactions and metal-polyphenol coordination. It shows potent, broad-spectrum antibacterial efficacy, achieving >90.00 % inhibition against both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) within 12 h. Additionally, this hydrogel facilitated the sustained release of rosmarinic acid and scavenged reactive oxygen species (ROS); in vitro, the hydrogel effectively scavenged over 80 % of ROS. It also modulated the immune microenvironment by promoting polarization toward M2-type macrophages with tissue repair functions and significantly reducing levels of pro-inflammatory cytokines, thereby exerting a more robust regulatory effect on inflammation. In vivo experiments demonstrate that treatment significantly accelerated closure, achieving ∼95 % wound healing within 14 days. Histological analysis confirms that inflammation is reduced, collagen alignment is increased, and epidermal regeneration is enhanced. Overall, the CS-RA/Zn2+-OHA hydrogel demonstrates considerable potential in the treatment of bacterium-infected wounds owing to its robust antibacterial, anti-inflammatory, and antioxidant properties, thereby offering a highly effective and safe therapeutic strategy for wound management.