Research progress on radioactive quantum dots for biomedical applications

Quantum dots (QDs) have been widely applied in bioimaging and oncological therapeutics owing to their unique photophysical and photochemical properties. However, conventional QDs typically require excitation from an external light source, which limits their utility in the in vivo imaging and treatment of deep-seated tissues and metastatic tumours. Conversely, radionuclides can achieve deep tissue imaging and treatment without external light source, yet they often lack multifunctional applications. Radioactive quantum dots (RQDs) emerge as an integrative solution that overcomes the limitations of both constituent materials. By harnessing the decay energy of radionuclides for self-excitation, RQDs overcome the penetration barrier of conventional QDs. Simultaneously, they incorporate the rich photophysics of QDs to achieve high-resolution multimodal imaging and combination therapy, thereby circumventing the lack of multifunctionality in radionuclides. This review mainly summarises the properties of RQDs, their synthesis strategies and their applications in bioimaging and cancer therapeutics. Finally, we discuss the future potential of RQDs in the integration of tumour diagnosis and treatment, aiming to provide guidance for researchers in medicine and engineering.