• Carbon quantum dots (CQDs) are synthesized via top-down (arc discharge, electrochemical, laser ablation) and bottom-up (hydrothermal, microwave, template) methods, with bottom-up offering environmental friendliness and high water solubility.
• CQDs serve as fluorescent probes for early tumor diagnosis and real-time monitoring, and their surface modification enables targeted photothermal therapy.
• CQDs act as drug carriers for targeted delivery, reducing adverse effects, and in immunotherapy they convert 'cold' tumors to 'hot' tumors by triggering immunogenic cell death and reversing immunosuppression.
• Multimodal therapy integrating chemotherapy, phototherapy, and immunotherapy using CQDs achieves high tumor inhibition rates, highlighting their potential for efficient and low-toxicity cancer nanoplatforms.