Etching triangular silver nanoparticles to initiate the fluorescent response of Ru@SiO2 for sensitive detection of glutathione

Abstract

Fluorescent probes usually face the issue of photobleaching and premature leakage when they are directly exposed to exterior environment, causing poor photostability and low sensitivity. In this paper, Ru(bpy)32+ encapsulated fluorescent SiO2 nanoparticles (Ru@SiO2 NPs) were synthesized and used as fluorescent probe. The SiO2 nanoparticles were used as carriers to prevent the leakage of the probe. Triangular Ag nanoparticles (T-Ag NPs) were prepared as quenchers to construct a quenching system (Ru@SiO2-T-Ag NPs) with Ru@SiO2 NPs through inner filter effect (IFE). In this quenching system, T-Ag NPs were also designed as recognize units for glutathione (GSH) detection. When GSH existed, the GSH bond with T-Ag NPs to form Ag-S bonds, making the T-Ag NPs etched. In this case, the fluorescent signal of Ru@SiO2 NPs quenched by T-Ag NPs restored. The fluorescence recovery of the Ru@SiO2 NPs depended on GSH concentrations and thus it could realize the quantitative analysis of GSH. Under optimized conditions, the proposed assay had good analytical performance for the detection of GSH in the concentration range of 0.01–1 µM with a limit of detection (LOD) as low as 2.8 nM. This assay was also used to measure GSH levels in human serum samples. This work provides a new way for the fluorescent analysis of thiol biomolecules.