Ultrasmall nanoclusters: Synthesis and applications as an emerging platform for imaging and therapy

Background: Ultrasmall nanoclusters (USNCs) have attracted tremendous attention owing to their unique properties that make them desirable for the development of personalized medicine, such as tunable emission, straightforward modification, and renal clearance. Hence, USNCs have emerged as potential materials for nanotheranostics. Objective: For decades, great efforts have been devoted to the bio-applications of USNCs, promising platforms to satisfy the increasing demand for precise diagnostic and targeted therapeutics. Herein, we summarize the most recent advances of USNCs in biomedical applications and provide our perspective on the future development of USNCs. Results: This review briefly summarized the synthetic methods of metallic USNCs and discussed their recent applications for cancer imaging and therapy. Conclusion: USNCs have shown their potential for accurate diagnosis and specific delivery of therapeutics in preclinical research.