Fluorescent Au nanoclusters: recent progress and sensing applications

Recent progress in nanotechnology has given rise to a new class of fluorescent nanomaterials: fluorescent noble metal nanoclusters. The noble metal nanoclusters include Ag, Au, Cu and Pt and typically consist of a ligand shell and a metal core, which incorporates various numbers of atoms ranging from only a few to several hundred, with diameters <2 nm. Au nanoclusters are the most intensely studied of these materials because of their attractive features, including convenient synthesis, ultra-small size, fluorescent properties, excellent optical/colloidal stability and biocompatibility. This paper summarizes the common synthesis strategies for obtaining water-soluble, highly fluorescent Au nanoclusters using different capping agents, and highlights recent advances in their fluorescent sensing applications with an emphasis on the sensing mechanisms. We also consider the prospects, opportunities and challenges for the synthesis and application of Au nanoclusters.