Polyelectrolyte Electrophoresis in Nanochannels: A Dissipative Particle Dynamics Simulation

TL;DR

This study uses dissipative particle dynamics simulations to explore how electroosmotic flow affects polyelectrolyte mobility in nanochannels, revealing the importance of boundary slip conditions and electrostatic screening.

Contribution

It provides new analytic expressions for electroosmotic and total mobility in nanoconfined polyelectrolyte systems considering slip boundary conditions.

Findings

Polyelectrolyte mobility depends strongly on slip length and electric double layer width.

Analytic expressions match well with simulation results.

The dimensionless parameter κδ_B characterizes the effect of slippage.

Abstract

We present mesoscopic DPD-simulations of polyelectrolyte electrophoresis in confined nanogeometries, for varying salt concentration and surface slip conditions. Special attention is given to the influence of electroosmotic flow (EOF) on the migration of the polyelectrolyte. The effective polyelectrolyte mobility is found to depend strongly on the boundary properties, i.e., the slip length and the width of the electric double layer. Analytic expressions for the electroosmotic mobility and the total mobility are derived which are in good agreement with the numerical results. The relevant quantity characterizing the effect of slippage is found to be the dimensionless quantity $\kappa \: \delta_B$, where $\delta_B$ is the slip length, and $\kappa^{-1}$ an effective electrostatic screening length at the channel boundaries.