Naslov
Dielectric relaxation of genomic deoxyribonucleic acid

Autori
Tomić, Silvia ; Dolanski Babić, Sanja ; Vuletić, Tomislav ; Vurnek, Damir ; Krča, Sanja ; Ivanković, Dušica ; Žaja, Roko ; Podgornik, Rudi ; Griparić, Lorena

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
4th Symposium of Science and Technology of Nanomaterials / Dragan Mihailovič - Ljubljana : Institut Jožef Stefan, 2005

Skup
4th Symposium of Science and Technology of Nanomaterials

Mjesto i datum
Ljubljana, Slovenija, 24.10.2005. - 25.10.2005

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Nije recenziran

Ključne riječi
DNA dielectric relaxation; characteristic length scales

Sažetak
We report a detailed characterization of complex dielectric response of genomic Na-DNA aqueous solutions by means of low-frequency dielectric spectroscopy (100 Hz &#8211; 100 MHz) (S.Tomić et al., to be submitted, Phys.Rev.E). The results have revealed two broad relaxation modes of strength 20<&#61508; &#61541; LF<100 and 5<&#61508; &#61541; HF<20, centered at 1 kHz<&#61550; LF<70 kHz and 0.1 MHz<&#61550; HF<15 MHz. We attribute these processes to oscillating monovalent counterions surrounding the Na-DNA at two different length scales. Dielectric strength ratio is &#61508; &#61541; LF/&#61508; &#61541; HF &#61627; 3 and 5 for DNA solutions with high and low added salt, respectively. These values are independent of sample preparation protocol and remain fixed for all DNA concentrations and added salt (NaCl) ionic strengths studied (0.01<cDNA<5mg, 0.01<Is<4mM). Assuming Manning condensation r=0.76 (G.S.Manning, J.Chem.Phys.51, 924 (1969)), the results for DNA solutions with high added salt identifiy condensed and diffuse counterions as relaxation entities of the low-frequency (LF) and the high-frequency (HF) mode, respectively. An increased dielectric strength ratio value for low added salt solutions, questions the Manning result in this limit. Characteristic length scale of LF process, 50<LHF<750nm, varies as cDNA-0.33 and depends on added salt as Is-1. Conversely, characteristic length scale of HF process, 4<LHF<45nm, varies as cDNA-0.5 and is independent on added salt ionic strength. These features suggest the persistence length (J.Skolnick and M.Fixman, Macromolecules 10, 944 (1977)) and mesh size (P.G.de Gennes, P.Pincus, R.M.Velasco and F.Brochard, J.Phys.(Paris) 37, 1461 (1976)) as characteristic length scales at which LF and HF process takes place, respectively. They also suggest the origin of dielectric relaxation as an intrinsic property of DNA conformational state in aqueous solutions.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Kemija, Biologija

POVEZANOST RADA