Mussel-inspired photothermal antibacterial multi-network hydrogel for cascade-enhanced infected wound healing

The clinical treatment of infected skin injuries caused by exogenous bacteria presents significant challenges, and traditional therapies struggle to achieve multiple therapeutic effects simultaneously. Herein, a mussel-inspired photothermal antibacterial self-repairing hydrogel (BA-PDZn-N) was designed for accelerating infected wound healing. Multi-network structures were constructed through free radical polymerization and dynamic borate bonding between acrylamide, 3-acrylamidophenylboronic acid, and polydopamine (PDA), as well as metal ligand chelation between PDA and Zn²⁺ for uniform porosity. Insertion of β-nicotinamide nucleotide (NMN) through hydrogen bonding as a bioactive substance enhances the antioxidant, cell migration, and vascular regeneration properties of the system. Inspired by the adhesion mechanism of mussels, the introduction of PDA endows the hydrogel with high adhesion, tensile properties (>1400 %), and rapid self-repair within 30 s. Based on the photothermal conversion properties of PDAZn²⁺ and the inherent antibacterial properties of Zn²⁺ and NMN, the hydrogel is synergistically endowed with strong antibacterial efficacy. The inhibition rate of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Methicillin-resistant Staphylococcus aureus (MRSA) under near infrared (NIR) irradiation is up to 99.11 %, 89.24 %, and 99.88 %, respectively. It also possesses excellent antioxidant, hemostatic, and cytocompatibility properties. In the wound model of S. aureus infection in SD rats, the BA-PDZn-N2 gel significantly reduced the inflammatory response while promoting the regeneration of epidermal structures, hair follicles, and vascular networks. These cascading therapeutic effects from immediate bacterial eradication and oxidative stress alleviation to sustained tissue reconstruction establish the hydrogel as a multifunctional platform for complex wound management.