title: A regenerative electrochemical sensor based on oligonucleotide for the selective determination of mercury(II).
abstract: We have developed a selective, sensitive, and re-usable electrochemical sensor for Hg2+ ion detection. This sensor is based on the Hg2+-induced conformational change of a single-stranded DNA (ssDNA) which involves an electroactive, ferrocene-labeled DNA hairpin structure and provides strategically the selective binding of a thymine-thymine mismatch for the Hg2+ ion. The ferrocene-labeled DNA is self-assembled through S-Au bonding on a polycrystalline gold electrode surface and the surface blocked with 3-mercapto-1-propanol to form a mixed monolayer. The modified electrode showed a voltammetric signal due to a one-step redox reaction of the surface-confined ferrocenyl moiety. The 'signal-on' upon mercury binding could be attributed to a change in the conformation of ferrocene-labeled DNA from an open structure to a restricted hairpin structure. The differential pulse voltammetry (DPV) of the modified electrode showed a linear response of the ferrocene oxidation signal with increase of Hg2+ concentration in the range between 0.1 and 2 microM with a detection limit of 0.1 microM. The molecular beacon mercury(II) ion sensor was amenable to regeneration by simply unfolding the ferrocene-labeled DNA in 10 microM cysteine, and could be regenerated with no loss in signal gain upon subsequent mercury(II) ion binding.
authors.affiliation: Department of Chemistry, Seoul National University, Seoul 151-747, South Korea.
authors.forename: Donghoon
authors.initials: D
authors.lastname: Han
authors.forename: Yang-Rae
authors.initials: YR
authors.lastname: Kim
authors.forename: Jeong-Wook
authors.initials: JW
authors.lastname: Oh
authors.forename: Tae Hyun
authors.initials: TH
authors.lastname: Kim
authors.forename: Rakesh Kumar
authors.initials: RK
authors.lastname: Mahajan
authors.forename: Jong Seung
authors.initials: JS
authors.lastname: Kim
authors.forename: Hasuck
authors.initials: H
authors.lastname: Kim
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation; D004277:DNA, Single-Stranded / Q000737:chemistry; D055664:Electrochemical Techniques / Q000295:instrumentation*; D004566:Electrodes; D017743:Equipment Reuse; D005296:Ferrous Compounds / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D008628:Mercury / Q000032:analysis* / Q000494:pharmacology; D000075163:Metallocenes; D009690:Nucleic Acid Conformation / Q000187:drug effects; D009841:Oligonucleotides / Q000737:chemistry*
chemical_list: D004277:DNA, Single-Stranded; D005296:Ferrous Compounds; D000075163:Metallocenes; D009841:Oligonucleotides; D006046:Gold; D008628:Mercury; C004998:ferrocene