Objective To develop a wound dressing that promotes diabetic wound healing by removing ROS and explore its mechanism. Methods Manganese tetraoxide nanozyme was prepared， and its structure and properties were characterized by materials science testing. The biocompatibility and anti-oxidative stress ability of nanozyme were tested by in vitro cell  experiments. The skin defect model of diabetic mice was used to verify the performance of the material in promoting wound healing by gross observation and histology. Results Manganese tetraoxide nanozyme is about 5 nanometers in size， with both Mn2+and Mn3+on the surface. It has good crystallinity， dispersibility and enzyme activity， and has no cytotoxicity at concentrations below 8 μg/mL. In in vitro experiments， the M1 marker increased significantly by 5.1-9.7 times after the addition of ROS. After the addition of manganese tetraoxide nanozyme， the M1 marker was significantly downregulated， with no difference from the control group （P＞0.05）. On the 14th day of the in vivo experiment， only 0.3% of the wound surface remained in the material group，8.5% in the control group， and 3.7% in the blank control group， with significant statistical differences （P<0.000 1）. Conclusion Manganese tetraoxide nanozymes were successfully prepared in this study， which

have good safety and efficacy. The combined in vivo and in vitro experimental results show that the material can effectively remove ROS， alleviate the effects of various adverse factors in the wound， and ultimately promote wound healing， providing a new choice for wound dressings in clinical practice.

Nanozymes, Reactive oxygen species, Oxidative stress, Macrophage polarization, Diabetic wound