A fluorescent sensor array based on silver nanoclusters for identifying heavy metal ions

The rapid, simple and reliable identification of heavy metal ions has attracted increasing attention of researchers. This work constructed a fluorescent sensor array by using 4 kinds of polymer templated silver nanoclusters (Ag NCs) as the sensing elements. This sensor array can be used for identifying 7 kinds of heavy metal ions including Pb²⁺, Fe³⁺, Cu²⁺, Cd²⁺, Cr³⁺, Co²⁺ and Ni²⁺. The fluorescence intensity ratios of Ag NCs after and before adding metal ions were applied as the output signals. We used principal component analysis (PCA) to reduce the dimensions of data variables and obtained a PCA scatter plot that could clearly distinguish every kind of 7 metal ions. This sensor array had a good performance when the ions concentration was in the range of 15–800 μM at pH of 7. The sensor array could also clearly discriminate these 7 heavy metal ions spiked in tap water. The Ag NCs-based sensor array could also be used as a fluorescence lifetime sensor array for the discrimination of metal ions. Taken all together, the developed sensor array holds great promise for practical analysis in the environment.