Self-reporting alkalinity-responsive hydrogel for visual monitoring and microenvironment remodeling of seawater-immersed infected wounds

Seawater-associated infected wounds involve alkaline and hyperosmotic stress, polymicrobial contamination, biofilms, and persistent inflammation, collectively delaying healing. Herein, we developed QCB-Au@SPG, a pH-responsive hydrogel integrating fluorescent antibacterial QCB-Au, an alkali-sensitive SA-PBA network, and photocrosslinkable GelMA. QCB-Au@SPG exhibited a linear fluorescence response across pH 4–8 (R² = 0.998), enabling semi-quantitative visualization of pH variation, while alkaline conditions moderately enhanced QCB-Au release. The hydrogel reduced the survival rates of S. aureus , E. coli , and V. vulnificus to 0.55%, 7.46%, and 0.53%, respectively, and markedly inhibited biofilms. It also enhanced Nrf2/HO-1-associated antioxidant defense, alleviated mitochondrial oxidative injury, and restored ATP production, while ML385 partially reversed these protective effects. In a rat seawater-associated infected wound model, QCB-Au@SPG visually indicated temporal pH changes, reduced bacterial survival to below 11% on Day 3, and achieved 97.81% wound closure on Day 14. Histological analyses further showed reduced inflammation, organized collagen deposition, and enhanced neovascularization. Overall, QCB-Au@SPG integrates semi-quantitative pH sensing, alkaline-enhanced release, antibacterial activity, and microenvironmental regulation, providing a promising platform for seawater-associated wound management.