Highly luminescent silver nanoclusters with tunable emissions: cyclic reduction-decomposition synthesis and antimicrobial properties

This paper reports a facile aqueous-based synthesis method for highly luminescent Ag nanoclusters (NCs) with tunable emissions. The key strategy was to use a reduction-decomposition-reduction cycle to modify the Ag NC intermediates that were further subjected to size/structure focusing. The as-modified Ag NC intermediates were more robust in water against the subsequent etching by thiol ligands, making a mild size-/structure-focusing environment possible, which produced highly luminescent Ag NCs with a well-defined size and structure. Ag NCs with intense red and green emission were successfully synthesized by this method. These Ag NCs possessed a well-defined size and structure (Ag-16(SG)(9) and Ag-9(SG)(6)), and exhibited excellent stability in the aqueous phase. Our highly luminescent Ag NCs also possessed superior antimicrobial properties against the multidrug-resistant bacteria Pseudomonas aeruginosa, via generating a high concentration of intracellular reactive oxygen species. NPG Asia Materials (2013) 5, e39; doi:10.1038/am.2013.3; published online 8 February 2013