On the importance of hydrodynamic interactions in polyelectrolyte electrophoresis

TL;DR

This study uses molecular dynamics simulations to show that hydrodynamic interactions significantly influence polyelectrolyte electrophoresis, affecting mobility and effective charge estimations, and highlights their importance in modeling experimental behavior.

Contribution

The paper introduces a novel method to estimate effective charge and demonstrates the critical role of hydrodynamic interactions in polyelectrolyte electrophoresis modeling.

Findings

Hydrodynamic interactions are crucial for accurate electrophoresis modeling.

Effective friction differs from diffusion-based friction.

Hydrodynamic interactions explain constant mobility in long chains.

Abstract

The effect of hydrodynamic interactions on the free-solution electrophoresis of polyelectrolytes is investigated with coarse-grained molecular dynamics simulations. By comparing the results to simulations with switched-off hydrodynamic interactions, we demonstrate their importance in modelling the experimentally observed behaviour. In order to quantify the hydrodynamic interactions between the polyelectrolyte and the solution, we present a novel way to estimate its effective charge. We obtain an effective friction that is different from the hydrodynamic friction obtained from diffusion measurements. This effective friction is used to explain the constant electrophoretic mobility for longer chains. To further emphasize the importance of hydrodynamic interactions, we apply the model to end-labeled free-solution electrophoresis.