Dresden 2014 – scientific programme

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BP: Fachverband Biologische Physik

BP 13: Posters: DNA/RNA and related enzymes

BP 13.7: Poster

Tuesday, April 1, 2014, 09:30–12:30, P1

Dielectric spectroscopy of DNA up to 110 GHz — Elena Ermilova, Frank Bier, and •Ralph Hölzel — Fraunhofer Institute for Biomedical Engineering Am Mühlenberg 13, 14476 Potsdam-Golm, Germany

Dielectric studies of DNA aqueous solutions still contribute to a better understanding of the interaction mechanisms between biological molecules, solvent, their ionic environment and electromagnetic fields at upper GHz and lower THz frequencies. Reflection measurements using a vector network analyzer allow a fast and uncomplicated determination of permittivity spectra from the measured complex reflection coefficient. In the present study we report the experimental results on dielectric relaxation of Na-DNA at various concentrations. Permittivity measurements were performed in the broad frequency range between 25 MHz and 110 GHz in a single sweep by means of a vector network analyzer. The permittivity spectra of DNA solutions exhibit a complex behaviour with several dispersion regions attributed to different relaxation mechanisms. Resulting from fitting to the double Cole-Cole model we resolved two dispersion regions: around 100 MHz and 20 GHz, respectively, and analysed their relaxation strengths and relaxation times.The wide frequency range provides possibilities for better analysis of the relaxation process attributed to the water dipoles in the presence of DNA macromolecules. The small dimension of the coaxial sensor allows to reduce the sample volume, which opens new possibilities for dielectric spectroscopy of well defined highly concentrated DNA solutions, as well as biological and synthetic polymer solutions.