Kinetically Controlled Direct Synthesis of Ag Nanoclusters as Precursor of Luminescent AgAu Alloy Nanoclusters for Aluminum Ions Detection

Direct preparation of silver nanoclusters is of great significance for their applications. In this work, by selecting sodium cyanoborohydride as a weak reducing agent to control the kinetics of the reduction reaction, we successfully prepared silver nanoclusters protected by thiol-containing ligands, including mercaptosuccinic acid, cysteine, and glutathione. Based on the silver nanoclusters protected by mercaptosuccinic acid, silver-gold alloy nanoclusters were obtained through a gold doping reaction. Spectroscopic and particle size analyses showed that the silver-gold alloy nanoclusters exhibited aggregation-induced emission enhancement (AIEE) properties. A fluorescent probe for aluminum ions was developed based on the silver-gold alloy nanoclusters. In the presence of methionine and mercaptoacetic acid, the probe demonstrated good selectivity for aluminum ion detection. The linear range of this detection method was 0 to 192 μM, with a detection limit of 1.6 μM. The working mechanism of this detection method was further investigated through spectroscopic analysis.