Highly sensitive recognition of Pb(2+) using Pb(2+) triggered exonuclease aided DNA recycling.

Here, we have demonstrated an ultra-high sensitive detection platform with the detection limit of 5pM for an environmental toxin-Pb(2+). We designed a Pb(2+) triggered exonuclease aided DNA recycling system to improve the detection sensitivity. In our system, a Pb(2+) dependent 8-17 DNAzyme and its substrate were used to form hybridization duplex. In the presence of Pb(2+), 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 Pb(2+) detection are accomplished and the detection limit of Pb(2+) was down to 5pM which is about 1000 times lower than the traditional detection method based on the 8-17 DNAzyme.