Carbon quantum dots for biological thermometry: Applications and advances

Carbon quantum dots (CQDs) have recently emerged as promising fluorescent nanothermometers for biological applications, due to their tunable photoluminescence, low cytotoxicity, and chemical versatility. The changes in their fluorescence properties with temperature have opened new ways for precise thermal mapping at the cellular and tissue levels. This review presents a comprehensive overview of the fundamental mechanisms underlying CQD-based thermometry, emphasizing advances in material design, surface passivation, and environmental resilience. Particular attention is given to strategies that improve their stability in complex biological environments, a critical requirement for reliable intracellular sensing. Recent applications, including live-cell and in vivo thermometry, are highlighted to illustrate the expanding scope of CQD-based thermal probes. Future developments, such as near-infrared emissive CQDs, long-term biostability, and integration with machine learning and hybrid nanomaterials to achieve dynamic, high-precision thermal sensing, are outlined. By summarizing both foundational principles and emerging innovations, this review aims to provide a way to advance CQDs as indispensable tools in biomedical diagnostics, therapeutic monitoring, and thermal biology research.