Electrochemistry of Methylene Blue Bound to a DNA-Modified Electrode
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 ^(32)P 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-(CH_2)_6-p-AGTACAGTCATCGCG 3' was obtained from coulometric titrations and gave an affinity constant equal to 3.8(5) × 10^6 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.
Additional Information
© 1997 American Chemical Society. Received August 1, 1996. Publication Date (Web): January 29, 1997. We are grateful to the NIH (GM49216 to J.K.B.), the Research Corporation (M.G.H.), the Camille and Henry Dreyfus Foundation (M.G.H.), and the NSF (DUE-9551647 to M.G.H.) for their financial support. In addition, we thank Ashish Bansal for assistance with the ellipsometry experiments and Professor F. C. Anson for helpful discussions.Attached Files
Supplemental Material - bc31.pdf
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Additional details
- Eprint ID
- 65929
- DOI
- 10.1021/bc960070o
- Resolver ID
- CaltechAUTHORS:20160405-110030531
- NIH
- GM49216
- Research Corporation
- Camille and Henry Dreyfus Foundation
- NSF
- DUE-9551647
- Created
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2016-04-06Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field