title: Ionic mobility in DNA films studied by dielectric spectroscopy.
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 ·10(6) 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.
authors.affiliation: Grenoble Electrical Engineering Laboratory (G2ELab), Université Joseph Fourier, 25 rue des Martyrs, 38042, Grenoble cedex 9, France.
authors.forename: Abdelkader
authors.initials: A
authors.lastname: Kahouli
authors.forename: Jessica
authors.initials: J
authors.lastname: Valle-Orero
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Garden
authors.forename: Michel
authors.initials: M
authors.lastname: Peyrard
mesh_terms: D000818:Animals; D004247:DNA / Q000737:chemistry*; D044704:DNA, A-Form / Q000737:chemistry; D059371:DNA, B-Form / Q000737:chemistry; D058266:Dielectric Spectroscopy; D017097:Electric Impedance; D007477:Ions; D008094:Lithium; D046911:Macromolecular Substances / Q000737:chemistry; D012964:Sodium; D013696:Temperature
chemical_list: D044704:DNA, A-Form; D059371:DNA, B-Form; D007477:Ions; D046911:Macromolecular Substances; D004247:DNA; D008094:Lithium; D012964:Sodium