Single-atom catalysts (SACs) are a type of atomically dispersed nanozymes with the highest atom utilization, which employ low-coordinated single atoms as the catalytically active sites. SACs not only inherit the merits of traditional nanozymes, but also hold high catalytic activity and superb catalytic selectivity, which ensure their tremendous application potential in environmental remediation, energy storage and conversion, chemical industry, nanomedicine, etc. Nevertheless, undesired aggregation effect of single atoms during preactivation and reaction processes is significantly enhanced owing to the high surface free energy of single atoms. In this case, appropriate substrates are requisite to prevent the aggregation event through the powerful interactions between the single atoms and the substrates, thereby stabilizing the high catalytic activity of the catalysts. In this review, the synthetic methods and characterization approaches of SACs are first described. Then the application cases of SACs in nanomedicine are summarized. Finally, the current challenges and future opportunities of the SACs in nanomedicine are outlined. It is hoped that this review may have implications for furthering the development of new SACs with improved biophysicochemical properties and broadened biomedical applications.

Fluorescent silicon nanoparticles (SiNPs), a type of ultrasmall zero‐dimensional metal‐free silicon‐containing nanomaterials, are featured by excellent biocompatibility, good photoluminescence stability, and easy surface modification property. SiNPs have been widely applied in bioimaging, photoelectric devices, sensing, cancer therapies, and anti‐counterfeiting. In this minireview, the recent advancements of SiNPs in imaging and killing microorganisms (i. e., bacteria, bacterial spores, and fungi) and bacterial biofilms are summarized. Moreover, the synthesis and modification of these SiNPs are mentioned. Finally, concise summary and outlook related to the review topic are provided, and the future challenges are briefly discussed.