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

In this paper, we report a new assay for the rapid detection of Pb super(2+) 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)u(i)-thiolate nanoclusters with ultra-bright fluorescence in the presence of high concentrations of metal ions. However, if two metal ions (e.g. Zn super(2+) and Pb super(2+)) were both used for aggregating Au(i)-glutathione, there is a synergistic aggregation effect on the complex. A very low concentration of Pb super(2+) could induce apparent fluorescence enhancement. Under the optimal experimental conditions, the relationship between fluorescence changes ( Delta F) of the aggregation system and the addition of Pb super(2+) (c, mu M) in the range from 0.50 to 40.0 mu M was measured as Delta F= 2.8 + 5.2 c, with the correlation coefficient (R super(2)) of 0.996. Moreover, we carried out a visual fluorescence detection of Pb super(2+) under violet-light irradiation. The increasing fluorescence can be easily distinguished by color pictures using the naked eye.