Gold nanoclusters: synthetic strategies and recent advances in fluorescent sensing

Fluorescent gold nanoclusters (AuNCs) have emerged as ideal sensor probes in different research fields such as environmental, biological and clinical applications. AuNCs have acquired a paramount importance in sensing applications owing to their unique physicochemical and luminescence characteristics including excellent photostability and biocompatibility, high surface to volume ratio, besides size-dependent luminescence, large stokes shift, and high emission rates. In this review, we will pay special attention on the recent advances in the different synthetic strategies of AuNCs. Different parameters affecting photoluminescence properties of AuNCs and their quantum yield including AuNCs size, core composition, valence state of Au atoms, and ligand effect will be discussed in detail. This review will also provide a comprehensive and recent look on the various AuNCs-based sensing systems developed for the detection of heavy metal ions, inorganic anions, small biomolecules, protein tumor markers, enzymes, and nucleic acids. This review demonstrates the high sensitivity, selectivity, simplicity, and low cost of AuNCs as sensing probes for the various targeted analytes.