Green-emitting fluorescence Ag clusters: facile synthesis and sensors for Hg2+ detection

Abstract

Bovine serum albumin (BSA) has proven to be particularly effective for the synthesis of Ag clusters due to its free cysteine residue in an alkaline environment. However, the currently used BSA-directed synthesis method is still complicated and uses BSA only as a stabilizing agent. In this study, we developed a simpler method for the synthesis of new fluorescent Ag clusters using BSA as a reducing and stabilizing agent. The as-prepared Ag clusters exhibited high green fluorescence emission (∼548 nm). Different changes in the pH were used for the synthesis of Ag clusters with different sizes. The results indicated that higher pH led to a smaller size. Furthermore, the Ag clusters were successfully applied in Hg²⁺ detection. The lowest detectable concentration was estimated to be 4.0 nM with a large range from 4.0 nM to 400.0 nM. MTT assays showed that the biotoxicity of the as-prepared Ag clusters was significantly lower than that of NaBH₄-reduced nano-silver.