title: Impedimetric immobilized DNA-based sensor for simultaneous detection of Pb2+, Ag+, and Hg2+.
abstract: An unlabeled immobilized DNA-based sensor was reported for simultaneous detection of Pb(2+), Ag(+), and Hg(2+) by electrochemical impedance spectroscopy (EIS) with [Fe(CN)(6)](4-/3-) as redox probe, which consisted of three interaction sections: Pb(2+) interaction with G-rich DNA strands to form G-quadruplex, Ag(+) interaction with C-C mismatch to form C-Ag(+)-C complex, and Hg(2+) interaction with T-T mismatch to form T-Hg(2+)-T complex. Circular dichroism (CD) and UV-vis spectra indicated that the interactions between DNA and Pb(2+), Ag(+), or Hg(2+) occurred. Upon DNA interaction with Pb(2+), Ag(+), and Hg(2+), respectively, a decreased charge transfer resistance (R(CT)) was obtained. Taking advantage of the R(CT) difference (ΔR(CT)), Pb(2+), Ag(+), and Hg(2+) were selectively detected with the detection limit of 10 pM, 10 nM, and 0.1 nM, respectively. To simultaneously (or parallel) detect the three metal ions coexisting in a sample, EDTA was applied to mask Pb(2+) and Hg(2+) for detecting Ag(+); cysteine was applied to mask Ag(+) and Hg(2+) for detecting Pb(2+), and the mixture of G-rich and C-rich DNA strands were applied to mask Pb(2+) and Ag(+) for detecting Hg(2+). Finally, the simple and cost-effective sensor could be successfully applied for simultaneously detecting Pb(2+), Ag(+), and Hg(2+) in calf serum and lake water.
authors.affiliation: Department of Chemistry, Beijing Normal University, Beijing, China, 100875.
authors.forename: Zhenzhen
authors.initials: Z
authors.lastname: Lin
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Li
authors.forename: Heinz-Bernhard
authors.initials: HB
authors.lastname: Kraatz
mesh_terms: D002412:Cations / Q000737:chemistry; D002942:Circular Dichroism; D003545:Cysteine / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D058266:Dielectric Spectroscopy / Q000379:methods*; D004492:Edetic Acid / Q000737:chemistry; D005295:Ferrocyanides / Q000737:chemistry; D054856:G-Quadruplexes; D007854:Lead / Q000032:analysis*; D008628:Mercury / Q000032:analysis*; D010084:Oxidation-Reduction; D012834:Silver / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D002412:Cations; D005295:Ferrocyanides; C116383:ferrocyn; D007854:Lead; D012834:Silver; D004247:DNA; D004492:Edetic Acid; D008628:Mercury; D003545:Cysteine