XX International Grassland Congress 2005

ICSM Conference 2006

Offered Abstract or Poster Submission Form

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Dielectric spectroscopy of DNA aqueous solutions Names of authors 1: Silvia Tomic 2: Sanja Dolanski Babic 3: Tomislav Vuletic 4: Sanja Krca others: Dusica Ivankovic, Lorena Griparic and Rudi Podgornik Author for correspondence Name: Silvia Tomic Address, Line 1: Institut za fiziku Address, Line 2: P.O.Box 304 Address, Line 3: HR-10001 Zagreb Address, Line 4: Croatia Address, Line 5: Phone (include intl access code): 385 1 4698820 Fax (include intl access code): 385 1 4698889 e-mail: [email protected] Preferred Session at Conference (refer to Conference Programme for correct title): Indicate title of most appropriate session:

Biomaterials and Bio-nanotechnology

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Non-standard poster displays Give a brief description of any additional aids you would like to use (e.g. video, computer) and likely space requirement. Note that it may not be possible to facilitate all such requests.

Type your abstract on the following page, using the Author Instructions for Offered Abstracts published on www.conferencepartners.ie/icsm. Save this Submission Form and your abstract as one file in Microsoft Word with the surname of the first author, followed by initials as the file name (e.g. ‘Smyth TS’). E-mail this to [email protected] Dielectric Spectroscopy of DNA Aqueous Solutions

S.Tomić1*, S.Dolanski Babić1,2, T.Vuletić1, S.Krča3, D.Ivanković3, L.Griparić4 and R.Podgornik5

1Institut za fiziku, Zagreb, Croatia 2Dept. of Physics and Biophysics, Medical School, University of Zagreb, Zagreb, Croatia 3Rudjer Bošković Institute, Zagreb, Croatia 4Dept. of Biological Chemistry, David Geffen School of Medicine, UCLA, Los Angeles, CA 5Dept.of Physics, University of Ljubljana and J .Stefan Institute, Ljubljana, Slovenia and Laboratory of Physical and Structural Biology NICHD, National Institute of Health, Bethesda, MD

We demonstrate the power of low-frequency dielectric spectroscopy (40 Hz – 110 MHz) as an highly-sensitive and non-destructive technique to detect dispersion of DNA aqueous solutions and give information on the fundamental length scales that determine the structure of these solutions composed of many DNA polymers1. Results for polydisperse genomic Na-DNA

(most of fragments with 20 kbp) reveal two broad relaxation modes of strength 20<LF<100 2 and 5<HF<20, centered at 0.5 kHz<LF<70 kHz and 0.1 MHz<HF<15 MHz . We discuss possible assignments for these relaxation modes inside the framework of the standard double layer model for polarization response of charged biopolymers in solution3. The results show that there are three fundamental length scales that determine the dielectric response of a semidilute DNA solution, each of them following the power law behavior with a distinct exponent. These are the average separation between the polyelectrolyte chains, or equivalently the screening length of DNA acting as its own salt, the salt-dependent persistence length of a single polyelectrolyte chain and the mesh size of the polyelectrolyte solution.

References: 1. F. Bordi, C. Cametti and R.H. Colby, J.Phys.: Condens. Matter 16, R1423 (2004). 2. S.Tomic et al., submitted to Phys.Rev.Lett. (February 2006). 3. A.V.Dobrynin and M.Rubinstein, Prog.Polym.Sci. 30, 1049 (2005) and A.V.Dobrynin, R.H.Colby and M.Rubinstein, Macromolecules 28, 1859 (1995).