Hydrogels with TA/Cu2+ release and NIR-II photothermal synergistic antibacterial and antioxidant properties for healing of bacterial-infected wounds

Bacterial infections pose a significant threat to the healing of human skin wounds, as the reactive oxygen species (ROS) they produce can significantly delay the wound healing process, ultimately leading to the formation of chronic wounds and even endangering human life. Therefore, this study successfully constructed a dynamically reversible hydrogel network through dual crosslinking of Schiff base bonds and hydrogen bonds using oxidized hyaluronic acid (OHA), carboxymethyl chitosan (CMCS), and tannic acid (TA). By loading Cu@PDA, the OCTC2 hydrogel wound dressing was prepared, exhibiting synergistic antibacterial and antioxidant properties through TA/Cu²⁺ release and NIR-II photothermal effects. We used FTIR, XRD, SEM, and TEM to thoroughly analyse the specific composition and morphology of the Cu@PDA and hydrogel. We measured the injectability, adhesion, NIR-II photothermal, and antibacterial properties of each group of hydrogels. The results showed that TA and Cu@PDA endowed the hydrogel with excellent antioxidant properties, enabling effective scavenging of various free radicals. Additionally, OCTC2, which possesses sustained-release TA/Cu²⁺ capability, achieves antibacterial rates of over 94 % against S. aureus and E. coli. Under the combined effect of NIR-II photothermal therapy, it can achieve highly efficient bacterial killing (99.8 %), effectively promoting the healing of bacterial infection wounds. OCTC2 holds promise as a potential ideal hydrogel dressing for treating bacterial-infected wounds.