Eur. Phys. J. E (2014) 37: 82
https://doi.org/10.1140/epje/i2014-14082-5

Regular Article

Ionic mobility in DNA films studied by dielectric spectroscopy

¹ Grenoble Electrical Engineering Laboratory (G2ELab), Université Joseph Fourier, 25 rue des Martyrs, 38042, Grenoble cedex 9, France
² Institut Laue Langevin, BP 156, 6, rue Jules Horowitz, 38042, Grenoble Cedex 9, France
³ CNRS, Institut NEEL, F-38042, Grenoble, France
⁴ Université Grenoble Alpes, Institut NEEL, F-38000, Grenoble, France
⁵ Laboratoire de Physique, Ecole Normale Supérieure de Lyon, 46 allée d’Italie, 69364, Lyon Cedex 07, France

^* e-mail: michel.peyrard@ens-lyon.fr

Received: 3 June 2014
Revised: 14 July 2014
Accepted: 8 September 2014
Published online: 26 September 2014

Abstract

Double-helix DNA molecules can be found under different conformational structures driven by ionic and hydration surroundings. Usually, only the B-form of DNA, which is the only form stable in aqueous solution, can be studied by dielectric measurements. Here, the dielectric responses of DNA molecules in the A- and B-form, oriented co-linearly within fibres assembled in a film have been analyzed. The dielectric dispersion, permittivity and dissipation factor, have been measured as a function of frequency, strength voltage, time, temperature and nature of the counter-ions. Besides a high electrode polarization component, two relaxation peaks have been observed and fitted by two Cole-Cole relaxation terms. In the frequency range that we investigated (0.1 Hz to 5 10⁶ Hz) the dielectric properties are dominated by the mobility and diffusivity of the counter-ions and their interactions with the DNA molecules, which can therefore be characterized for the A- and B-forms of DNA.