Mesoscale modelling of polyelectrolyte electrophoresis

Area of Science:

• Polymer Physics
• Computational Chemistry
• Physical Chemistry

Background:

• Electrophoresis is a key technique for analyzing charged polymers (polyelectrolytes).
• Understanding polyelectrolyte behavior in solution requires accounting for complex interactions.
• Atomistic simulations are computationally expensive for larger systems.

Purpose of the Study:

• To investigate the electrophoretic behavior of flexible polyelectrolyte chains using a mesoscopic simulation approach.
• To demonstrate the significance of hydrodynamic interactions and ion effects on polyelectrolyte motion.
• To validate a coarse-grained model against experimental data.

Main Methods:

• A coarse-grained molecular dynamics model was developed.
• The model was coupled with a mesoscopic fluid simulation using the Lattice-Boltzmann approach.
• Free-solution electrophoresis of polyelectrolytes was simulated.

Main Results:

• Hydrodynamic interactions significantly influence electrophoretic motion.
• The length-dependence of electrophoretic mobility was explained by scaling behavior of effective charge and friction.
• The model accurately reproduced experimental measurements across a wide range of polyelectrolyte lengths (nm to >100 nm).

Conclusions:

• A suitable coarse-grained approach can accurately describe polyelectrolyte electrophoresis.
• Chemical details and fluid structure can be neglected if electrostatic and hydrodynamic interactions are properly included.
• This mesoscopic model bridges the gap between single molecules and macromolecules, exceeding the reach of atomistic simulations.