Formation and stabilization of fluorescent gold nanoclusters using small molecules

Biological molecular imaging and sensing requires fluorophores that are not only stable and bright, but also small enough to allow the unencumbered observation of the movement of proteins. Toward this goal, we have studied the formation of fluorescent metallic gold nanoclusters stabilized by small molecule ligands. The morpholine and piperazine backbones of Good's buffers were used to template fluorescent clusters, through a process of etching of nanoparticles first formed in the reaction. The clusters are found to be subnanometer sized, with nanosecond fluorescence lifetimes and as bright, or brighter, than the commercial dye norharmane.