Toggling Between Blue- and Red-Emitting Fluorescent Silver Nanoclusters

A very efficient protocol for synthesizing highly fluorescent, protein-templated silver nanoclusters (Ag/NCs) has been discussed. Two types of Ag/NCs (Ag-9/HSA and Ag-14/HSA), although showing significant differences in their photophysical properties, can be interconverted at will, which makes this study unique. The Ag/HSA NCs have been quantified by several spectroscopic techniques, and they find tremendous applications as photoluminescent markers. Besides their rather easy synthetic methodology, our Ag/HSA NCs show two-photon excitation properties that enable them to be used in bioimaging.