Carbon dots based nanozymes: Synthesis, structure, catalytic mechanisms and applications

Nanozymes, a class of artificial enzymes combining nanomaterial properties and catalytic functions, have garnered significant interest across multidisciplinary fields since their discovery. Among them, carbon dots (CDs), a carbon-based nanozyme with a size less than 10 nm, emerged as a promising biomedical nanozyme due to their stable fluorescence, excellent biocompatibility, low toxicity, and versatile mimicry of natural enzyme activities. Recent advances of CDs with diverse enzyme-like activities in biomedical and biological detection fields has attracted widespread attention on their structure-property-application relationships. In this review, we first summarize the precursors and synthesis strategies of CDs, emphasizing the role of precursor selection in tailoring surface functional groups, and introducing the universality of hydrothermal methods. We conducted an in-depth analysis of the catalytic mechanism of CDs based-nanozymes, and discussed the relationship between their structural features (such as size, surface groups, doping, etc.) and different enzyme simulated activities. Furthermore, we systematically discuss the biomedical applications of CDs, including anti-inflammatory, antibacterial, and antitumor therapies, as well as their utility in biosensing and environmental detection. Finally, we address the current challenges and future prospects of CDs in nanomedicine, offering insights for the rational design and targeted applications of this emerging nanozyme.