Zekun Yan, Yupeng Liu, Jinyun Tan, Songnan Qu
Carbon dots (CDs) have emerged as a transformative class of luminescent nanomaterials for biomedical applications, offering superior biocompatibility, photostability, and tunability compared to conventional organic dyes and inorganic quantum dots. This review distinguishes itself by establishing a critical "Structure-Property-Application" feedback framework. We comprehensively summarize the rational design of CDs, specifically elucidating how core size, surface chemistry, and heteroatom doping can be precisely engineered to tailor optical emission into the near-infrared II window. Furthermore, the versatile roles of CDs in cancer theranostics are critically discussed, encompassing their utility in subcellular tracking, image-guided surgery, and multifunctional therapeutic platforms such as photothermal therapy (PTT), photodynamic therapy (PDT), and targeted drug delivery. Finally, we address the current challenges regarding scalability, reproducibility, and biosafety, providing a perspective on the future roadmap for the clinical translation of high-performance CD-based agents.