title: Electrochemical DNA sensor for specific detection of picomolar Hg(II) based on exonuclease III-assisted recycling signal amplification.
abstract: An ultrasensitive methodology was successfully developed for the quantitative detection of picomolar Hg(2+) based on the combination of thymine-Hg(2+)-thymine (T-Hg(2+)-T) coordination chemistry and exonuclease III-aided recycling signal amplification. Single-strand probe DNA was immobilized on an Au electrode via an Au-S bond. In the presence of Hg(2+), the probe DNA hybridized with the target DNA containing four thymine-thymine (T-T) mismatches via the Hg(2+)-mediated coordination of T-Hg(2+)-T base pairs. Then the probe DNA in the DNA duplex was specifically recognized and selectively digested by exonuclease III; in contrast the target DNA was safely dissociated from the DNA duplexes to subsequently hybridize with a new signal probe, leading to target recycling and signal amplification. As a result, the peak current caused by the electrostatic interactions of [Ru(NH3)6](3+) cations with the backbone of the probe DNA decreased by different degrees, corresponding to the Hg(2+) concentrations. Under the optimum conditions, the proposed electrochemical DNA biosensor showed a robust detection limit as low as 1 pM (S/N = 3), with a wide linear range from 0.01 to 500 nM and good selectivity. In addition, the proposed method was successfully applied to assay Hg(2+) in real environmental samples.
authors: Dalian University of Technology, School of Environmental and Biological Science and Technology, Dalian, Liaoning, China. zhaohuim@dlut.edu.cn.
authors: Xiaorong
authors: X
authors: Gan
authors: Huimin
authors: H
authors: Zhao
authors: Shuo
authors: S
authors: Chen
authors: Xie
authors: X
authors: Quan
mesh_terms: D015374:Biosensing Techniques / Q000379:methods; D015342:DNA Probes / Q000737:chemistry / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000378:metabolism; D060766:Drinking Water / Q000032:analysis*; D055664:Electrochemical Techniques / Q000379:methods*; D004784:Environmental Monitoring / Q000379:methods*; D005090:Exodeoxyribonucleases / Q000378:metabolism; D006046:Gold / Q000737:chemistry; D061925:Immobilized Nucleic Acids / Q000737:chemistry* / Q000378:metabolism; D057230:Limit of Detection; D008628:Mercury / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D013941:Thymine / Q000737:chemistry / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D015342:DNA Probes; D004277:DNA, Single-Stranded; D060766:Drinking Water; D061925:Immobilized Nucleic Acids; D014874:Water Pollutants, Chemical; D006046:Gold; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III; D008628:Mercury; D013941:Thymine