The Recent Advances in the Development of Multifunctional Carbon Dot Nanozymes with Defined Catalytic Mechanisms for Biomedical Applications

Carbon dot (CD) nanozymes represent an emerging class of enzyme-mimicking nanomaterials, which recently received intensive attention due to their tunable catalytic properties, exceptional biocompatibility, and scalable fabrication. They have been widely applied in biomedical fields such as light-enhanced antibacterial agents, multimodal tumor imaging/therapy platforms, and sensitive pollutant biosensors. However, key challenges such as controllable synthesis, mechanistic elucidation, and validation of long-term in vivo biosafety remain to be resolved. In this review, we first delve into the fundamental catalytic mechanisms of CD nanozymes, highlighting the roles of surface functional groups, heteroatom doping, and electronic structure in determining enzyme-like activities (e.g., SOD, POD, CAT, oxidase). We then critically compare top-down and bottom-up synthesis strategies, with an emphasis on how synthesis parameters influence catalytic performance. Subsequently, we review their multifunctional biomedical applications, focusing on antimicrobial therapy, tumor detection, and synergistic photothermal-photodynamic-ferroptosis therapies, as well as environmental monitoring. Finally, we outline future priorities including AI-assisted design, strategic surface engineering, and green manufacturing to advance clinical and environmental translation. This comprehensive review integrates fundamental catalytic mechanisms, synthetic strategies, and cutting-edge applications, providing a critical roadmap to advance CD nanozyme research from mechanistic understanding to clinical translation, thereby guiding interdisciplinary innovation in the field.