Silk Fibroin Nanozyme Hydrogel with Self-Supplied H2O2 for Enhanced Antibacterial Therapy

Peroxidase-mimicking nanozyme therapy has emerged asa powerfultool in antibacterial therapy. Due to the critical role in reactiveoxygen species (ROS) generation, various in situ H2O2 supplying nanoagents have been developed toguarantee the therapeutic effect. However, the challenges in relianceon external stimulus, instability of the H2O2 donor, and risk of leakage limited their antibacterial efficiencyand actual application. In this work, we fabricated an injectablesilk fibroin/ZnO NP/mica-Fe3O4 (SFZM)composite nanozyme hydrogel with spontaneous H2O2 generation and peroxidase-mimicking nanozyme properties. The ZnONPs could produce H2O2 without light or otherexternal stimulus. Under a weak acid environment, the H2O2 produced from ZnO NPs could be in situ transformed to ROS by magnetic mica-Fe3O4 nanosheets, leading to nearly 50% enhancement in antibacterial activitycompared with a silk fibroin-ZnO hydrogel. Meanwhile, the SFZMnanozyme hydrogel displayed in vivo adhesion andhemostasis properties. As a result, the SFZM hydrogel could acceleratethe healing of bacteria-infected wounds in rats. More interestingly,the ZnO exhibited continued H2O2 generationduring at least 12 days, suggesting the long-term enhanced antibacterialeffect of the SFZM hydrogel. Also, the SFZM nanozyme hydrogel showedlow nanomaterial leakage and demonstrated biocompatibility both in vitro and in vivo.