Gold nanoclusters in cancer drug delivery: Advances and emerging applications

Gold nanoclusters (AuNCs), ultrasmall clusters of several to 100 gold atoms, have shown promise in cancer diagnosis and treatment over the past two decades. These clusters, protected by templates or ligands, catalytic activity, and strong luminescence, exhibit high chemical stability and biocompatibility. They are structurally engineered to modulate surface electronic states, particularly in the near-infrared region II (NIR-II) window, enhancing long-wavelength photoluminescence. This allows real-time imaging in living organisms to monitor disease progression and treatment responses. Advances in AuNCs have led to advancements in disease-related diagnostics and therapies. Proteins, peptides, or other biomolecules will serve as structural scaffolds or encapsulating ligands in the future development of functionalized AuNCs for theranostic applications. Moreover, AuNCs have also been used in fluorescent bioimaging, multimodal imaging, and as nanocarriers for chemotherapeutic drugs. Their significance in biomedical research is evident in their diverse applications in cancer imaging, therapy, and beyond. Furthermore, the present article extensively discusses the current applications of AuNCs in anticancer drug delivery to various other emerging applications.