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 H2O2. The oxidization of glucose by glucose oxidase coupled with the fluorescence quenching of PEI-Ag nanoclusters by H2O2 can be used to detect glucose. Under optimum conditions, the fluorescence intensity quenched linearly in the range of 500 nM-100 mu M with high sensitivity. The detection limit for H2O2 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 x 10(-6) to 1.0 x 10(-5) M and 1.0 x 10(-5) to 1.0 x 10(-3) M with a detection limit of 8.0 x 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 H2O2 has been discussed. (C) 2012 Elsevier B.V. All rights reserved.