Fluorescence enhancement induced by the interaction of silver nanoclusters with lead ions in water

We have synthesized fluorescent and stable silver nanoclusters (AgNCs) capped with poly (methacrylic acid), PMAA, by UV irradiation process. The NCs are well dispersed in aqueous solution and present a uniform distribution with an average dimension of 1.45 ± 0.26 nm. The fluorescence excited at 340 nm was found to be sensitive to the presence of heavy metal ions in solution. In particular, a peculiar fluorescence enhancement was detected upon interaction with lead(II) ions. A linear behavior of the fluorescence intensity as a function of the Pb2+ concentration was measured and a detection limit of 60 nM was estimated. A possible mechanism of the interaction between AgNCs and metal ions is discussed.