Electrochemistry of methylene blue bound to a DNA-modified electrode

Shana O. Kelley, Jacqueline K. Barton*, Nicole M. Jackson, Michael G. Hill

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

469 Scopus citations

Abstract

Gold surfaces have been derivatized with 15-base-pair double-stranded DNA oligonucleotides containing a pendant 5' hexanethiol linker. The electrochemistry of intercalated methylene blue has been investigated at these modified electrodes. Chronocoulometry, cyclic voltammetry, ellipsometry, and quantitation via 32P labeling are all consistent with a surface coverage of ≤75% with the DNA helices stacked at an angle from the electrode surface. Cyclic voltammetry at low methylene blue/duplex stoichiometries yields well-behaved surface waves with E° = -0.25 V (vs SCE), a value 0.03 V negative of that in aqueous solution. A binding isotherm for methylene blue at an electrode derivatized with the double-stranded sequence 5' SH-(CH2)6-p-AGTACAGTCATCGCG 3' was obtained from coulometric titrations and gave an affinity constant equal to 3.8(5) x 106 M-1 with a saturation value of 1.4(2) methylene blue intercalators per DNA duplex. Taken together, these experiments support a model for the surface morphology in which DNA duplexes are densely packed; methylene blue therefore reversibly binds to sites in the DNA that are close to the bulk solution. Electrochemistry at DNA-derivatized electrodes provides a valuable methodology to examine DNA-bound redox reactions and may offer new insight into DNA-mediated electron transfers.

Original languageEnglish (US)
Pages (from-to)31-37
Number of pages7
JournalBioconjugate Chemistry
Volume8
Issue number1
DOIs
StatePublished - Jan 29 1997
Externally publishedYes

ASJC Scopus subject areas

  • Bioengineering
  • Biotechnology
  • Biomedical Engineering
  • Pharmacology
  • Pharmaceutical Science
  • Organic Chemistry

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