Dynamics of a driven confined polyelectrolyte solution

TL;DR

This study uses molecular dynamics simulations to explore how the mobility and separation efficiency of polyelectrolytes are affected by confinement surface charge density and dielectric mismatch, revealing optimal conditions for size-based separation.

Contribution

It introduces a detailed simulation approach that accounts for surface polarization effects, demonstrating how charge density and dielectric mismatch influence polyelectrolyte separation.

Findings

Mobility varies non-monotonically with surface charge density.

Optimal charge density enhances size-based separation.

Surface polarization effects can be exploited for improved separation.

Abstract

The transport of polyelectrolytes confined by oppositely charged surfaces and driven by a constant electric field is of interest in studies of DNA separation according to size. Using molecular dynamics simulations that include surface polarization effect, we find that the mobilities of the polyelectrolytes and their counterions change non-monotonically with the confinement surface charge density. For an optimum value of the confinement charge density, efficient separation of polyelectrolytes can be achieved over a wide range of polyelectrolyte charge due to the differential friction imparted by the oppositely charged confinement on the polyelectrolyte chains. Furthermore, by altering the placement of the charged confinement counterions, enhanced polyelectrolyte separation can be achieved by utilizing surface polarization effect due to dielectric mismatch between the media inside and outside the confinement.