Time domain reflectometry techniques used as an analytical tool to investigate water molecules bound to solid-state deoxyribonucleic acid (DNA)

Abstract

In this study, the dielectric properties of ion-reduced Na- and Mg-DNA have been investigated over a frequency range 10⁵–10¹⁰ Hz as a function of hydration and temperature, using time domain reflectometry techniques. Three distinct dispersions have been indentified, centred at frequencies of ca. 10⁷, 10⁸ and 10¹⁰ Hz, respectively. The lowest frequency dispersion has been attributed to localised relaxation of counter-ions associated with the phosphate groups of the DNA double helix (G. P. Archer, S. Bone and R. Pethig, J. Mol. Electron., 1990, 6, 199). The highest frequency dispersion is thought to be the result of the rotational relaxation of DNA-bound water molecules. The origin of the dispersion centred in the 10⁸ Hz region is discussed in terms of a number of possible relaxation processes.