title: A novel graphene-DNA biosensor for selective detection of mercury ions.
abstract: A novel electrochemical biosensor for sensitive and selective detection of mercury (II) ions (Hg²⁺) based on a DNA grafted graphene is proposed. Graphene oxide (GO) was reduced by dopamine, and then the single-strand probe DNA modified at the 5'-end with an alkylamino modifier (NH₂-ssDNA) was grafted on the reduced graphene oxide (RGO) surface via Michael addition reaction. In the presence of Hg²⁺, the target DNA with four thymine-thymine (T-T) mismatches would hybridize with the probe DNA on the glassy carbon electrode (GCE) through T-Hg²⁺-T coordination chemistry. The hybridization of the two oligonucleotides leads to the increase in the peak currents of [Ru(NH₃)₆]³⁺, which could be used for electrochemical sensing of Hg²⁺. The difference in the value of the peak currents of [Ru(NH₃)₆]³⁺ before and after DNA hybridization was linear with the concentration of Hg²⁺ in the range from 8.0×10⁻⁹ to 1.0×10⁻⁷ M with a linear coefficiency of 0.996. The detection limit was 5.0×10⁻⁹ M (S/N=3). The proposed electrochemical biosensor is rapid, convenient and low-cost for effective sensing of Hg²⁺. Particularly, the proposed method was applied successfully to the determination of Hg²⁺ in real environmental samples.
authors.affiliation: School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, 19A YuQuan Road, 100049 Beijing, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Hong
authors.initials: H
authors.lastname: Zhao
authors.forename: Zhijiao
authors.initials: Z
authors.lastname: Wu
authors.forename: Ying
authors.initials: Y
authors.lastname: Xue
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Zhang
authors.forename: Yujian
authors.initials: Y
authors.lastname: He
authors.forename: Xiangjun
authors.initials: X
authors.lastname: Li
authors.forename: Zhuobin
authors.initials: Z
authors.lastname: Yuan
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D002413:Cations, Divalent / Q000032:analysis; D004247:DNA / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000379:methods; D006108:Graphite / Q000737:chemistry*; D057230:Limit of Detection; D008628:Mercury / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*
chemical_list: D002413:Cations, Divalent; D006108:Graphite; D004247:DNA; D008628:Mercury