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Differential Ionic Permeation of DNA-Modified Electrodes

Ceres, Donato M. and Udit, Andrew K. and Hill, Haley D. and Hill, Michael G. and Barton, Jacqueline K. (2007) Differential Ionic Permeation of DNA-Modified Electrodes. Journal of Physical Chemistry B, 111 (3). pp. 663-668. ISSN 1520-6106. doi:10.1021/jp066324c.

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Ionic permselectivity of DNA films has been investigated by the analysis of the electrochemical response of methylene blue (MB) as a function of pH and ionic strength on DNA-modified electrodes in aqueous p-nitrophenol (p-NP) and phosphate buffers. We have observed a linear Pourbaix diagram in p-NP buffer indicating that the reduction of MB occurs with a two-electron plus one-proton reaction. Interestingly, in phosphate buffer the Pourbaix diagram is curved and this suggests that the thermodynamics of MB incorporated in the film depend also on the ratio of mono- versus divalent anions in the bulk. This result indicates that DNA films do not behave as pure ion-exclusion films, but instead there is a differential permselectivity that depends on the identity of the anions. Based on this consideration of the ionic distribution in the films, we provide a new method for the analysis of the DNA surface coverage based on AC impedance of an anionic species, ferricyanide. The methodology is of particular value in analyzing DNA hybridization and dehybridization. This approach presents an advantage compared to standard ruthenium hexammine assays since our methodology is insensitive to film morphology, and is highly sensitive to the amount of negative charge on the surface.

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Barton, Jacqueline K.0000-0001-9883-1600
Additional Information:© 2007 American Chemical Society. Received: September 26, 2006; In Final Form: November 10, 2006. Publication Date (Web): January 3, 2007. We are grateful to the National Institutes of Health (GM61077) for their financial support of this research.
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Official Citation:Differential Ionic Permeation of DNA-Modified Electrodes Donato M. Ceres, Andrew K. Udit, Haley D. Hill, Michael G. Hill, and Jacqueline K. Barton The Journal of Physical Chemistry B 2007 111 (3), 663-668 DOI: 10.1021/jp066324c
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64814
Deposited By: Ruth Sustaita
Deposited On:29 Feb 2016 18:40
Last Modified:10 Nov 2021 23:35

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