Double-strand DNA-templated formation of Copper nanoparticles as fluorescent probe for label free nuclease enzyme detection

The double-strand DNA (dsDNA) can act as an efficient template for the formation of copper nanoparticles (Cu NPs) with high fluorescence, whereas the single-strand DNA (ssDNA) cannot support the formation of Cu NPs. This difference in fluorescent signal generation can be used for the detection of nuclease cleavage activity. Thus, a label-free strategy for sensitive detection of nuclease has been developed. The sensor contains a complete complementary dsDNA which acts as a template for the formation of Cu NPs and generation of fluorescence signal. The enzyme S1 nuclease was taken as the model analyte. Upon addition of S1 nuclease into the sensing system, the DNA was cleaved into fragments, preventing the formation of the Cu NPs and resulting in low fluorescence. In order to achieve the system's best sensing performance, a series of experimental conditions were optimized. Under the optimized experimental conditions, the sensor exhibits excellent performance (e.g., a detection limit of 0.3 U mL(-1) with high selectivity). This possibly makes it an attractive platform for the detection of Si nuclease and other biomolecules. (C) 2012 Elsevier B.V. All rights reserved.