A New Model For DNA Charge Transfer: Variable Electronic Circuitry

The Electrochemical Society, Inc., Abs. 1377, 204th Meeting, 2003

Merrill Garnett and C.V. Krishnan Garnett McKeen Lab, Inc.

The variety of theories and experiments (1-6) in the literature on charge transfer or conduction by DNA should not be considered contradictory, but rather as contributions to an emerging equivalent circuitry of intricate and embedded nature.

In the phonon assisted polaron hopping model (3), it was proposed that the distance dependent long range electron transfer is controlled by transient structural distortions in DNA. We believe this dynamics is the key to developing electronic equivalent circuitry. We have developed a method for insight into DNA charge transfer, especially the "ion gated transport" mechanism (2). Our method uses non-steady-state impedance measurements (7-9). Unlike other systems where a dopant is introduced by high energy ionizing radiation, we use mildly positive potentials of the mercury electrode. We take advantage of the unique properties of the aqueous chemistry of the mercurous ion to inject a dopant in a narrow voltage band.

The basis for electronic device oscillation signals is in repetitive unit cells having capacitive or inductive behavior or both as occurs in crystals. We observe liquid crystal structures in DNA that are responsive to specific frequencies and dopants.

Figures 1,2 and 3 show Mott-Schottky, admittance, and complex plane plots for (A) DNA,1mg/mL in the presence of (B) 0.01M NaCl, (C) 0.01M NaCl and 10% CH3OH, and (D) 0.05M sodium acetate (NaAc), 1mg/mL hyaluronic acid (HA)(dielectric), and 0.3%H2O2 (dopant). These show how DNA can vary its electronic behavior depending on the ions, and molecules in the milieu. The charge transfer catalysis is shown in dynamic complex plane impedance plots. In special environments capacitance is followed by discharge. The dynamics is further visible in Mott-Schottky plots and admittance spectra.

We propose an open-ended model in terms of electronic circuits, to explain charge transfer in DNA (ct). The data suggest that DNA assumes different electronic circuit configurations depending on its interactions with available ions, molecules, and solvents. Impedance analysis shows that charge-discharge catalysis can occur in the hydration mantle. The hydration grooves are parallel to the known charge transfer path between gene bases. The parallel conduction geometries support a mutual inductance. The resultant energy reflections and propagations would produce the efficiency of a multi-stranded transmission cable.

References :
1. C. Wan, T. Fiebig, O. Schiemann, J. K.Barton, A. H. Zewail, Proc. Natl.Acad. Sci.USA., 97,14052(2000)
2. R. N. Barnett, C. L. Cleveland, A. Joy, U. Landman, G. B. Schuster, Science, 294, 567, 2001 and references therein.
3. G.B. Schuster, Acc. Chem. Res., 33, 253(2000)
4. B. Giese, Acc. Chem. Res., 33, 631(2000)
5. J. Jortner, 203rdMeeting of ECS, Paris 2003, Abstract 2488 .
6. V. May, E. Petrov, 203rdMeeting of ECS, Paris 2003, Abstract 2489
7. C.V.Krishnan, Merrill Garnett, 1stSpring Meeting of the International Society of Electrochemistry, Alicante, Spain, 2003, Abstract P06
8. C.V.Krishnan, Merrill Garnett, John L. Remo, 203rdMeeting of ECS, Paris 2003, Abstract 2703
9. C.V.Krishnan, Merrill Garnett, 226thMeeting of American Chemical Society, New York 2003, Abstract 670792 (submitted)