Oxidized alginate/carboxymethyl chitosan-based dynamic hydrogels via Schiff base reaction: BSA-stabilized Zn-doped Prussian blue nanozyme-embedded networks for pH-responsive antioxidant and antibacterial applications

Zn doping and BSA stabilization synergistically optimize Prussian blue nanozymes. • Zn doping narrows PB bandgap, boosting NIR photothermal conversion to 34.2%. • OSA/CMCS Schiff-base hydrogel shows self-healing and acid-triggered BPZ release. • OC@BPZ shows multi-enzyme-like ROS scavenging and > 92% antibacterial efficacy. Skin wounds are often complicated by bacterial infection, excessive oxidative stress, and mildly acidic microenvironments, which limit the efficacy of conventional single-function dressings. Here, we developed a pH-responsive dynamic composite hydrogel (OC@BPZ) by integrating bovine serum albumin-stabilized Zn-doped Prussian blue nanozymes (BPZ) into an oxidized sodium alginate/carboxymethyl chitosan Schiff base network. At the nanozyme level, BSA-mediated stabilization suppresses PB aggregation, whereas Zn doping modulates the electronic structure of the PB framework; at the matrix level, the dynamic imine network regulates the acidity-dependent release of the optimized nanozymes. The reversible imine bonds endow the hydrogel with self-healing ability, wound-conformal adaptability, and pH-responsive degradation, enabling enhanced nanozyme release under the mildly acidic wound microenvironment. The embedded BPZ nanozymes exhibit enhanced superoxide dismutase (SOD)-, catalase (CAT)-, and peroxidase (POD)-like activities, allowing efficient reactive oxygen species (ROS) scavenging and oxidative microenvironment regulation. Meanwhile, the optimized BPZ nanozymes exhibit enhanced NIR photothermal performance and antibacterial activity. Under 808 nm irradiation, OC@BPZ achieved antibacterial rates of 92.59%, 96.92%, and 97.53% against P. aeruginosa , E. coli , and S. aureus , respectively. In pH 5.5 medium, OC@BPZ released 82.4 ± 4% of BPZ over 12 days, confirming acid-responsive delivery. This cascade design combines structural responsiveness with catalytic and antibacterial functions, integrating pH-responsive release, ROS scavenging, and bacterial inhibition within a single hydrogel platform. Overall, these results demonstrate that OC@BPZ provides a promising multifunctional platform for responsive antibacterial and antioxidant wound-dressing applications. Download: Download high-res image (211KB) Download: Download full-size image An intelligent dynamic hydrogel integrating Zn-doped Prussian blue nanozymes is developed for multimodal antibacterial and antioxidant interventions. Benefiting from acid-responsive network dissociation and Zn-modulated electronic structures, it achieves on-demand nanozyme release, enabling robust multi-enzyme ROS scavenging coupled with highly efficient NIR-photothermal and ionic synergistic bactericidal capabilities.