Synthesis and Applications of Water-Soluble Fluorescent Silver Nanoclusters

Ag nanoclusters consisting of several AQ:1 to a hundred atoms with diameters less than 2 nm show molecule-like properties, including discrete electronic AQ:2 transitions and strong fluorescence. They have received considerable research interest due to their unique optical, electrical and chemical properties and potential applications in chemicaland biosensing. Ag nanoclusters exhibit excellent photostability, large Stokes shifts and high quantum yields, and therefore, they have become an important class of fluorophores for applications in imaging. Since most applications involve aqueous conditions, the synthesis of aqueous-stable and water-soluble Ag nanoclusters is critical. The synthesis of water-soluble Ag nanoclusters, however, is challenging because few-atom silver nanoclusters are highly reactive and will quickly aggregate to form large nanocrystals thus reducing their surface energy. Recently, many different synthetic approaches including radiolytic, chemical, sonochemical,