Silver atom doping to glutathione-protected gold nanoclusters substantially increases the photoluminescence intensity, while preserving the microenvironment and the surface reactivity. The higher amount of gold atom on the surface of the nanoclusters promotes stronger metallophilic interactions, resulting in greater structural compactness and reduced nonradiative relaxation pathways, thereby improving emission efficiency.

Glutathione (GSH) is a widely used surface ligand for stabilizing metal nanoclusters owing to its biocompatibility, strong metal-chelating ability, antioxidant properties, and minimal affinity for endogenous cellular proteins. However, the low quantum yield of GSH-protected gold nanoclusters (GSH-Au NCs) limits its practical applications. In the present study, silver (Ag) doping is employed in GSH-Au NCs to significantly enhance the photoluminescence intensity as well as lifetime, while preserving the microenvironment and the surface reactivity essential for subsequent functionalization. The doped nanoclusters exhibit a remarkable sixfold increase in luminescence. This is attributed to the modulation of metal(I)-thiolate motifs and the amplification of aurophillic interactions, leading to more rigid structure which help to reduce non-radiative deexcitation pathways.