DNA-Stabilized Silver Nanoclusters with High Yield of Dark State

Abstract

Fluorophores with long-lived dark states have gained special attention in bioimaging microscopy. Such states in DNA-stabilized fluorescent clusters, a new class of bioprobes, have already been employed in optically modulated imaging scheme, though the formation efficiency of the dark state is estimated to be less than 1%. We measured quantum yield of the dark state for the calf thymus DNA-stabilized Ag nanocluster using nonlinear fluorescence saturation spectroscopy. The obtained value of the yield of 25% suggested very efficient formation of the nonemitting long-lived transient species of the studied silver cluster–DNA complex presumably of charge-transfer nature. This result seems to be promising in further creating polymer-stabilized Ag nanoclusters with specially designed structure providing high efficiency of the dark state formation.