Dielectric relaxation of genomic deoxyribonucleic acid (CROSBI ID 517350)
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Podaci o odgovornosti
Tomić, Silvia ; Dolanski Babić, Sanja ; Vuletić, Tomislav ; Vurnek, Damir ; Krča, Sanja ; Ivanković, Dušica ; Žaja, Roko ; Podgornik, Rudi ; Griparić, Lorena
engleski
Dielectric relaxation of genomic deoxyribonucleic acid
We report a detailed characterization of complex dielectric response of genomic Na-DNA aqueous solutions by means of low-frequency dielectric spectroscopy (100 Hz – 100 MHz) (S.Tomić et al., to be submitted, Phys.Rev.E). The results have revealed two broad relaxation modes of strength 20<  LF<100 and 5<  HF<20, centered at 1 kHz< LF<70 kHz and 0.1 MHz< HF<15 MHz. We attribute these processes to oscillating monovalent counterions surrounding the Na-DNA at two different length scales. Dielectric strength ratio is   LF/  HF  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.
DNA dielectric relaxation; characteristic length scales
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Podaci o prilogu
33-x.
2005.
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objavljeno
Podaci o matičnoj publikaciji
4th Symposium of Science and Technology of Nanomaterials
Dragan Mihailovič
Ljubljana: Institut Jožef Stefan
Podaci o skupu
4th Symposium of Science and Technology of Nanomaterials
predavanje
24.10.2005-25.10.2005
Ljubljana, Slovenija