Dresden 2014 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 51: Charged Soft Matter II

CPP 51.5: Vortrag

Donnerstag, 3. April 2014, 16:00–16:15, ZEU 118

Ion friction causes current blockades in DNA translocation experiments — •Stefan Kesselheim and Christian Holm — Institute for Computational Physics, University of Stuttgart, Germany

We investigate the motion of potassium ions and water molecules parallel to the surface of a double stranded DNA molecule under an applied electric field by means of all-atom simulations. Overall we find, that it is described surprisingly well by a simple charged-cylinder model and the electrokinetic equations. The atomistic model, however, exhibits a significant reduction of the ion mobility close to the surface of the DNA, which we interpret as a microscopic friction effect, that is also mediated by the water.

In nanopore experiments the ion current is the main observable. Its modulation by the presence of macromolecules, such as DNA, can be used to infer information about the molecule. Our simulations indicate that the current reduction observed in most experiments is caused by the ion surface friction effect. Our model predicts the crossover electrolyte concentration between current reduction and current enhancement in agreement with experiments.