Luminescent metal nanoclusters: Biosensing strategies and bioimaging applications

Metal nanoclusters (MNCs) are ultrasmall metal-organic aggregates, composed of a metal core less than 2 nm and a protecting shell of metal-organic ligand motifs. The controlled aggregation of metal atoms (in the cluster core) and metal-organic ligand motifs (around the cluster core) renders MNCs with numerous molecule-like properties, among which strong and bright luminescence has attracted extensive basic and applied interests. It has now known that aggregation-induced emission is a feasible mechanism for controlling luminescence of MNCs, which makes it particularly useful in biosensing and bioimaging applications. Although the luminescence fundamentals and design principles largely determine the practicality and effectiveness of MNCs in biosensing and bioimaging applications, a systematic summary of this topic is lacking in the current literature. In this review, we aim to provide a concise discussion of the latest developments in biosensing and bioimaging applications of luminescent MNCs, highlighting their luminescence mechanisms, biosensing principles, and bioimaging strategies. Specifically, we first introduce the recent advances in the synthetic chemistry of MNCs, and then briefly discuss the luminescence fundamentals of MNCs. Then the design strategy and practicality of luminescent MNCs in biosensing and bioimaging applications are exemplified. We conclude the review with our perspectives on the further development of MNC-based optical probes in biosensing and bioimaging applications. Our review is expected to provide guidance for the future practice of designing and synthesizing luminescent MNCs for biomedical and other applications.

Automated summary

Metal nanoclusters (MNCs) are small metal-organic aggregates with molecule-like properties, particularly strong and bright luminescence, making them useful in biosensing and bioimaging applications. Aggregation-induced emission is a feasible mechanism for controlling the luminescence of MNCs. Despite the lack of a systematic summary in current literature, research on the design and practicality of luminescent MNCs for biomedical applications is advancing.