title: Signal enhancement for gene detection based on a redox reaction of [Fe(CN)(6)](4-) mediated by ferrocene at the terminal of a peptide nucleic acid as a probe with hybridization-amenable conformational flexibility.
abstract: Electrochemically enhanced DNA detection was demonstrated by utilizing the couple of a synthesized ferrocene-terminated peptide nucleic acid (PNA) with a cysteine anchor and a sacrificial electron donor [Fe(CN)(6)](4-). DNA detection sensors were prepared by modifying a gold electrode surface with a mixed monolayer of the probe PNA and 11-hydroxy-1-undecanethiol (11-HUT), protecting [Fe(CN)(6)](4-) from any unexpected redox reaction. Before hybridization, the terminal ferrocene moiety of the probe was subject to a redox reaction due to the flexible probe structure and, in the presence of [Fe(CN)(6)](4-), the observed current was amplified based on regeneration of the ferrocene moiety. Hybridization decreased the redox current of the ferrocene. This occurred because hybridization rigidified the probe structure: the ferrocene moiety was then removed from the electrode surface, and the redox reaction of [Fe(CN)(6)](4-) was again prevented. The change in the anodic current before and after hybridization was enhanced 1.75-fold by using the electron donor [Fe(CN)(6)](4-). Sequence-specific detection of the complementary target DNA was also demonstrated.
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan. aoki-h@aist.go.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Aoki
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Tao
mesh_terms: D004247:DNA / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D015342:DNA Probes / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D004563:Electrochemistry; D004566:Electrodes; D005295:Ferrocyanides / Q000737:chemistry*; D005296:Ferrous Compounds / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D000075163:Metallocenes; D021141:Nucleic Acid Amplification Techniques / Q000295:instrumentation / Q000379:methods*; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization / Q000379:methods; D010084:Oxidation-Reduction; D020135:Peptide Nucleic Acids / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D015342:DNA Probes; D005295:Ferrocyanides; D005296:Ferrous Compounds; D000075163:Metallocenes; D020135:Peptide Nucleic Acids; D013438:Sulfhydryl Compounds; D006046:Gold; D004247:DNA; C000170:ferric ferrocyanide; C004998:ferrocene