Polyethyleneimine-capped silver nanoclusters as a fluorescence probe for sensitive detection of hydrogen peroxide and glucose.

In this work, we utilized polyethyleneimine-capped silver nanoclusters (PEI-Ag nanoclusters) to develop a new fluorometric method for the determination of hydrogen peroxide and glucose with high sensitivity. The PEI-Ag nanoclusters have an average size of 2 nm and show a blue emission at 455 nm. The photostable properties of the PEI-Ag nanoclusters were examined. The fluorescence of the PEI-Ag nanoclusters could be particularly quenched by H(2)O(2). The oxidization of glucose by glucose oxidase coupled with the fluorescence quenching of PEI-Ag nanoclusters by H(2)O(2) can be used to detect glucose. Under optimum conditions, the fluorescence intensity quenched linearly in the range of 500 nM-100 μM with high sensitivity. The detection limit for H(2)O(2) was 400 nM. And a linear correlation was established between fluorescence intensity (F(0)-F) and concentration of glucose in the range of 1.0×10(-6) to 1.0×10(-5) M and 1.0×10(-5) to 1.0×10(-3) M with a detection limit of 8.0×10(-7) M. The method was used for the detection of glucose in human serum samples with satisfactory results. Furthermore, the mechanism of sensitive fluorescence quenching response of Ag nanoclusters to glucose and H(2)O(2) has been discussed.