Fluorescent detection of hydrogen peroxide and glucose with polyethyleneimine-templated Cu nanoclusters.

An interesting, simple, and label-free strategy for the detection of hydrogen peroxide and glucose has been developed with polyethyleneimine (PEI)-capped copper nanoclusters as a fluorescence probe in aqueous solution. The PEI-templated Cu nanoclusters which we have synthesized have an average diameter of 1.8 nm and show a blue emission at 480 nm. In the presence of hydrogen peroxide, the fluorescence of the Cu nanoclusters is quenched. Similarly, glucose oxidase catalyzes the oxidation of glucose to gluconic acid and H2O2, so we can also use this probe to detect glucose. Because of the high zymolyte specificity of glucose oxidase, the detection of glucose has good selectivity. Under the optimized experimental conditions, the linear ranges for H2O2 and glucose are 0.5-10 μM and 10-100 μM, respectively. And the detection limits for H2O2 and glucose are 0.4 and 8 μM, respectively. Furthermore, we discussed the mechanism of fluorescence quenching which is caused by the interaction between H2O2 and Cu nanoclusters. This sensing system has been applied successfully to the detection of glucose in human serum samples.