Volume 144, 2010
From the journal:

Faraday Discussions

Mesoscale modelling of polyelectrolyteelectrophoresis

Kai Grass*a  and  Christian Holm*abc  

* Corresponding authors

a Frankfurt Institute for Advanced Studies, Goethe University, Ruth-Moufang-Str. 1, Frankfurt/Main, Germany
E-mail: grass@fias.uni-frankfurt.de

b Max-Planck-Institut für Polymerforschung, Ackermannweg 10, Mainz, Germany

c Institute for Computational Physics, University of Stuttgart, Pfaffenwaldring 27, Stuttgart, Germany
E-mail: holm@icp.uni-stuttgart.de

Abstract

The electrophoretic behaviour of flexible polyelectrolyte chains ranging from single monomers up to long fragments of a hundred repeat units is studied by a mesoscopic simulation approach. Abstracting from the atomistic details of the polyelectrolyte and the fluid, a coarse-grained molecular dynamics model connected to a mesoscopic fluid described by the Lattice-Boltzmann approach is used to investigate free-solution electrophoresis. Our study demonstrates the importance of hydrodynamic interactions for the electrophoretic motion of polyelectrolytes and quantifies the influence of surrounding ions. The length-dependence of the electrophoretic mobility can be understood by evaluating the scaling behavior of the effective charge and the effective friction. The perfect agreement of our results with experimental measurements shows that all chemical details and fluid structure can be safely neglected, and a suitable coarse-grained approach can yield an accurate description of the physics of the problem, provided that electrostatic and hydrodynamic interactions between all entities in the system, i.e., the polyelectrolyte, dissociated counterions, additional salt and the solvent, are properly accounted for. Our model is able to bridge the single molecule regime of a few nm up to macromolecules with contour lengths of more than 100 nm, a length scale that is currently not accessible to atomistic simulations.

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Article information

DOI
https://doi.org/10.1039/B902011J
Article type
Paper
Submitted
30 Jan 2009
Accepted
20 Feb 2009
First published
10 Aug 2009

Faraday Discuss., 2010,144, 57-70

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Mesoscale modelling of polyelectrolyte electrophoresis

K. Grass and C. Holm, Faraday Discuss., 2010, 144, 57 DOI: 10.1039/B902011J

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