Carbon-based single-atom catalysts (SACs) have been widely studied in the field of biomedicine due to their excellent catalytic performance. However, carbon-based SACs usually aggregate during pyrolysis, which leads to the reduction of catalytic activity. Here, we describe a method to improve the monodispersion of SACs using silicon dioxide as a protective layer. The decoration of silicon dioxide serves as a buffer layer for individual nanoparticles, which is not destroyed during the pyrolysis process, ensuring the single-particle dispersion of the nanoparticles after etching. This approach increased the hydroxyl groups on the surface of Fe-SAC (Fe-SAC-SE) and improved its water solubility, resulting in a four times enhancement of the peroxidase (POD)-like activity of Fe-SAC-SE (58.4 U/mg) than that of non-protected SACs (13.9 U/mg). The SiO₂-protection approach could also improve the catalytic activities of SACs with other metals such as Mn, Co, Ni, and Cu, indicating its generality for SACs preparation. Taking advantage of the high POD-like activity, photothermal properties, and large specific surface area of Fe-SAC-SE, we constructed a synergistic therapeutic system (Fe-SAC-SE@DOX@PEG) for combining the photothermal therapy, catalytic therapy, and chemotherapy. It was verified that the photothermal properties of Fe-SAC-SE@DOX@PEG could effectively improve its POD-like activity, exhibiting excellent tumor-killing performance at the cellular level. This work may provide a general approach to improve the performances of SACs for disease therapy and diagnosis.

碳基单原子催化剂（SAC）因其优异的催化性能在生物医学领域得到了广泛的研究。然而，碳基SAC在热解过程中通常会聚集，从而导致催化活性降低。在这里，我们描述了一种使用二氧化硅作为保护层来改善 SAC 单分散性的方法。二氧化硅的装饰作为单个纳米颗粒的缓冲层，在热解过程中不会被破坏，保证了蚀刻后纳米颗粒的单颗粒分散。这种方法增加了Fe-SAC（Fe-SAC-SE）表面的羟基并提高了其水溶性，导致Fe-SAC-SE（58.4 U）的过氧化物酶（POD）样活性增强了四倍。 /mg）高于未受保护的 SAC（13.9 U/mg）。 SiO ₂保护方法还可以提高SAC与其他金属（例如Mn、Co、Ni和Cu）的催化活性，表明其对于SAC制备的通用性。利用Fe-SAC-SE的高POD活性、光热特性和大比表面积，我们构建了一个结合光热疗法、催化疗法的协同治疗系统（Fe-SAC-SE@DOX@PEG）和化疗。验证了Fe-SAC-SE@DOX@PEG的光热特性可以有效提高其POD样活性，在细胞水平上表现出优异的肿瘤杀伤性能。这项工作可能为提高 SAC 在疾病治疗和诊断方面的性能提供一种通用方法。