Polyelectrolyte Electrophoresis in Nanochannels: A Dissipative Particle Dynamics Simulation

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.