Tuning the photoluminescence of metal nanoclusters for selective detection of multiple heavy metal ions

In this work, we synthesized metal (Au, Ag or Cu)–based nanoclusters (NCs) with different photoluminescence (PL) properties and investigated their application for the specific detection of heavy metal ions in water samples. Bovine serum albumin (BSA) and thiosalicylic acid (TSA) acted as protecting ligands for the synthesis of metallic NCs (MNCs). The as–prepared TSA/BSA–Au NCs, TSA/BSA–Ag NCs and TSA/BSA–Cu NCs exhibit PL emission at 700, 624, and 430 nm, with average lifetimes of 1540, 30.9, and 11.7 ns, respectively, when excited at 350 nm. MNCs has a metal core and metal–thiolate shell, where shell species are Au₃₈–SR₂₄, Ag₉–SR₇ and Cu_3–14–SR_m in the TSA/BSA–Au NCs, TSA/BSA–Ag NCs, and TSA/BSA–Cu NCs, respectively. PL quenching of MNCs induced through metallophilic interaction, metal–thiol complexation and/or inner filter effect, which enables the quantitation of Hg²⁺, As³⁺, and Cr⁶⁺ ions, with linear ranges of 1–350, 1–20, and 50–400 nM, and with limits of detection of 0.25, 0.34 and 3.54 nM, respectively. The TSA/BSA–Au NCs, TSA/BSA–Ag NCs, and TSA/BSA–Cu NCs probe systems exhibit the advantages of simplicity, rapidity, selectivity, sensitivity, and practicality for the quantitation of metal ions in water samples.