Zinc Oxide-Copper Sulfide Nanozyme Hydrogels for Bone Defect Repair by Modulating the Bone Immune Microenvironment and Promoting Osteogenesis/Angiogenesis

Bone defects caused by trauma, tumors, or infections pose significant challenges to clinical treatment because of the complex pathological microenvironment they create. Elevated levels of inflammatory factors and reactive oxygen species (ROS) at the defect site disrupt the bone immune microenvironment, impeding bone regeneration. Concurrently, the vascular damage frequently associated with bone defects leads to hypoxia, further complicating therapeutic efforts. Although bone grafting remains a primary clinical approach, its efficacy is limited by these adverse conditions. In this study, a ZnO-CuS/F127 nanozyme hydrogel with multiple enzymatic activities was manufactured for bone defect repair via the modulation of the bone immune microenvironment and the promotion of osteo-/angiogenesis, which was accomplished via the encapsulation of ZnO-CuS nanoflowers synthesized via calcination into the F127 hydrogel matrix. ZnO-CuS bimetallic nanoenzymes exhibit robust catalase (CAT) and superoxide dismutase-like activities, enabling effective scavenging of diverse ROS species <i>in vitro</i>. In cellular assays, ZnO-CuS/F127 protected bone marrow mesenchymal stem cells [bone mesenchymal stem cells (BMSCs)] from ROS-induced cytotoxicity and promoted macrophage polarization toward the anti-inflammatory M2 phenotype, thus modulating the bone immune microenvironment. The ZnO-CuS/F127 hydrogel demonstrated potent proangiogenic and pro-osteogenic effects, attributed to its ability to upregulate the Wnt/β-catenin signaling pathway while inhibiting the NF-κB pathway in BMSCs, as confirmed by RNA sequencing. <i>In vivo</i>, the hydrogel exhibited exceptional hemostatic performance and facilitated bone defect repair in mouse hemorrhage and rat bone defect models while maintaining high biocompatibility and low cytotoxicity. This study highlights the use of the ZnO-CuS/F127 nanozyme hydrogel as a promising therapeutic strategy for bone defect repair. By modulating the immune microenvironment and promoting angiogenesis and osteogenesis, this multifunctional hydrogel offers innovative insights and a potential clinical solution for addressing the multifaceted challenges of bone regeneration.