Synergistic aggregating of Au(i)–glutathione complex for fluorescence “turn-on” detection of Pb(ii)

Abstract

In this paper, we report a new assay for the rapid detection of Pb²⁺ in aqueous solution based on aggregation induced emission of Au(I)–glutathione complex. Non-fluorescent oligomeric Au(I)–glutathione complex could aggregate to form Au(0)@Au(I)–thiolate nanoclusters with ultra-bright fluorescence in the presence of high concentrations of metal ions. However, if two metal ions (e.g. Zn²⁺ and Pb²⁺) were both used for aggregating Au(I)–glutathione, there is a synergistic aggregation effect on the complex. A very low concentration of Pb²⁺ could induce apparent fluorescence enhancement. Under the optimal experimental conditions, the relationship between fluorescence changes (ΔF) of the aggregation system and the addition of Pb²⁺ (c, μM) in the range from 0.50 to 40.0 μM was measured as ΔF = 2.8 + 5.2 c, with the correlation coefficient (R²) of 0.996. Moreover, we carried out a visual fluorescence detection of Pb²⁺ under violet-light irradiation. The increasing fluorescence can be easily distinguished by color pictures using the naked eye.