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

Peroxidase-mimicking nanozyme therapy has emerged as a powerful tool in antibacterial therapy. Due to the critical role in reactive oxygen species (ROS) generation, various in situ H2O2 supplying nanoagents have been developed to guarantee the therapeutic effect. However, the challenges in reliance on external stimulus, instability of the H2O2 donor, and risk of leakage limited their antibacterial efficiency and actual application. In this work, we fabricated an injectable silk fibroin/ZnO NP/mica–Fe3O4 (SFZM) composite nanozyme hydrogel with spontaneous H2O2 generation and peroxidase-mimicking nanozyme properties. The ZnO NPs could produce H2O2 without light or other external 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 activity compared with a silk fibroin–ZnO hydrogel. Meanwhile, the SFZM nanozyme hydrogel displayed in vivo adhesion and hemostasis properties. As a result, the SFZM hydrogel could accelerate the healing of bacteria-infected wounds in rats. More interestingly, the ZnO exhibited continued H2O2 generation during at least 12 days, suggesting the long-term enhanced antibacterial effect of the SFZM hydrogel. Also, the SFZM nanozyme hydrogel showed low nanomaterial leakage and demonstrated biocompatibility both in vitro and in vivo.