Highly sensitive recognition of Pb2+ using Pb2+ triggered exonuclease aided DNA recycling

Abstract

Here, we have demonstrated an ultra-high sensitive detection platform with the detection limit of 5pM for an environmental toxin—Pb2+. We designed a Pb2+ triggered exonuclease aided DNA recycling system to improve the detection sensitivity. In our system, a Pb2+ dependent 8–17 DNAzyme and its substrate were used to form hybridization duplex. In the presence of Pb2+, the substrate was cleaved and disassociated from the duplex. Then, the released 8–17 DNAzyme was used as a target of the exonuclease aided DNA recycling system which can amplify the fluorescence signal by recycling the 8–17 DNAzyme continuously. Then, the sensitive Pb2+ detection are accomplished and the detection limit of Pb2+ was down to 5pM which is about 1000 times lower than the traditional detection method based on the 8–17 DNAzyme.