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

• Published in: Analytical Sciences Vol. 24; no. 7; pp. 929 - 933
• Main Authors: AOKI, Hiroshi, TAO, Hiroaki
• Format: Journal Article
• Language: English
• Published: Singapore The Japan Society for Analytical Chemistry 01.07.2008; Springer Nature Singapore; Nature Publishing Group
• Subjects: Analytical Chemistry; Chemistry; Deoxyribonucleic acid; DNA; Electrodes; Hybridization; Nucleic acids; Redox reactions
• ISSN: 0910-6340; 1348-2246
• DOI: 10.2116/analsci.24.929

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.