Concepts on charge transfer through naturally vibrating DNA molecule

Delocalization of charges thorough DNA occurs due to the natural and continuous movements of molecule which stimulates the charge transfer through the molecule. A model is presented showing that the mechanism of electrical conduction occurs mainly by thermally-activated drift motion of holes under control of the localized carriers: where electrons are localized in the conduction band. These localized (stationary-trapped) electrons control the movements of the positive charges and do not play an effective role in the electrical conduction itself. It is found that the localized charge-carriers in the bands have characteristic relaxation times at 5 x 10 boolean AND(-2) s, 1.94 x 10 boolean AND(-4) s, 5x 10 boolean AND(-7) s, and 2 x 10 boolean AND(-11) s respectively which are corresponding to four intrinsic thermal activation energies 0.56 eV, 0.33 eV, 0.24 eV, and 0.05 eV respectively. The ac-conductivity of some published data are well fitted with the presented model and the total charge density in DNA molecule is calculated to be n = 1.88 x 10 boolean AND(19) cm boolean AND(-3) at 300 K which is corresponding to a linear electron density n = 8.66 x 10 boolean AND(3) cm boolean AND(-1) at 300 K. The model shed light on the role of transfer and/or localization of charges through DNA which has multiple applications in medical, nano-technical, bio-sensing and different domains. So, repair DNA by adjusting the charge transport through the molecule is future challenges to new medical applications. (C) 2012 Elsevier B.V. All rights reserved.