Gold nanorods-based FRET assay for sensitive detection of Pb2+ using 8-17DNAzyme

In this paper, we have reported a sensitive assay for fluorescence turn-on detection of Pb2+ in aqueous solutions based on FRET between gold nanorods (GNRs) and the FAM-labeled substrate strand of 8-17DNAzyme. The fluorescence of the FAM-labeled substrate strand is quenched when 8-17DNAzyme is adsorbed on GNRs surface through electrostatic interaction. In the presence of lead ions, the fluorescence is restored due to the decrease of FRET efficiency caused by the specific cleavage of the FAM-labeled substrate strand by the enzyme, which weakens the electrostatic interaction between the GNRs and short FAM-labeled DNA fragment. The interference of eleven common metal ions has been tested, indicating that Pb2+ can be selectively detected. This method exhibits a high sensitivity for Pb2+ with a detection limit of 61.8 pM and a linear range from 0.1 nM to 100 nM. It is a simple, sensitive, and selective method for Pb2+ detection. Moreover, this sensing system obtained satisfying results for Pb2+ detection in tap water samples.