Nanozymes with superoxide dismutase (SOD)-like activity have attracted increasing interest due to their ability to scavenge superoxide anion, the origin of most reactive oxygen species in vivo. However, SOD nanozymes reported thus far have yet to approach the activity of natural enzymes. Here, we report a carbon dot (C-dot) SOD nanozyme with a catalytic activity of over 10,000 U/mg, comparable to that of natural enzymes. Through selected chemical modifications and theoretical calculations, we show that the SOD-like activity of C-dots relies on the hydroxyl and carboxyl groups for binding superoxide anions and the carbonyl groups conjugated with the π-system for electron transfer. Moreover, C-dot SOD nanozymes exhibit intrinsic targeting ability to oxidation-damaged cells and effectively protect neuron cells in the ischemic stroke male mice model. Together, our study sheds light on the structure-activity relationship of C-dot SOD nanozymes, and demonstrates their potential for treating of oxidation stress related diseases.

具有超氧化物歧化酶（SOD）样活性的纳米酶因其清除超氧阴离子（体内大多数活性氧的来源）的能力而引起了越来越多的兴趣。然而，迄今为止报道的SOD纳米酶尚未达到天然酶的活性。在这里，我们报道了一种碳点（C-dot）SOD纳米酶，其催化活性超过10,000 U/mg，与天然酶相当。通过选定的化学修饰和理论计算，我们表明碳点的类 SOD 活性依赖于羟基和羧基来结合超氧阴离子，以及与 π 系统共轭的羰基进行电子转移。此外，C-dot SOD纳米酶表现出对氧化损伤细胞的内在靶向能力，并有效保护缺血性中风雄性小鼠模型中的神经元细胞。总之，我们的研究揭示了碳点 SOD 纳米酶的结构-活性关系，并证明了它们治疗氧化应激相关疾病的潜力。