EPL, 82 (2008) 46002
DOI: 10.1209/0295-5075/82/46002

Anomalous diffusion of ions at the surface of hydrated DNA molecule

A. Oleinikova¹, I. Brovchenko¹, A. Krukau¹ and A. K. Mazur<sup>2

1</sup>  Physical Chemistry, Dortmund University of Technology - Otto-Hahn-Str. 6, Dortmund, D-44227, Germany, EU
²  CNRS UPR9080, Institut de Biologie Physico-Chimique - 13, rue Pierre et Marie Curie, Paris, F-75005, France, EU

alla@pc2a.chemie.uni-dortmund.de
alexey@ibpc.fr

received 26 January 2008; accepted in final form 25 March 2008; published May 2008
published online 7 May 2008

Abstract
Diffusion of ions at the surface of the DNA molecule is found to be anomalous under various levels of hydration. The increase of the exponent of anomalous diffusion from 0.66 to 0.81 upon hydration correlates with the appearance and growth of the spanning network of hydration water. Water shows anomalous diffusion with exponent 0.84, independent of the hydration level. We argue that the anomalous diffusion of ions is governed by the spatial disorder of the surface of hydrated DNA that depends on water clustering and cannot be ignored even under full hydration. The effect of local confinement and temporal disorder on the translational motion is noticeable at small time scales only.

PACS
66.10.-x - Diffusion and ionic conduction in liquids.
61.20.Ja - Computer simulation of liquid structure.
87.14.gk - DNA.

© EPLA 2008