Electric Field Driven Motion of Flexible Polyelectrolytes – A Molecular Dynamics Study
T.S. Lo, B. Khusid, A. Acrivos and J. Koplik
New Jersey Institute of Technology, US
multi-scale modeling, molecular dynamics, dipole moments, dielectrophoresis, nanoscopic channels
Our work aims to develop multi-scale computational procedures for simulating the dielectrophoretic behavior of biomolecules in micro- and nano-electrofluidics, which combine electrohydrodynamics with molecular theories for the macromolecule polarization caused by the distortion of the surrounding counterion cloud. Molecular dynamics (MD) simulations are used to model the transport of flexible polyelectrolytes suspended in a solvent, with or without added salt, under the action of electric fields. The major difference between our model and most available MD simulations of polyelectrolytes is that solvent atoms are explicitly represented, so that hydrodynamic interactions are included naturally with no ad hoc assumptions needed. The polyelectrolyte is modeled as a negatively charged freely-jointed bead-spring chain. The charges interact through a Coulomb interaction and other molecular interactions are included via Lennard-Jones potentials. We have benchmarked our model by computing the equilibrium single chain structure factor and various pair correlation functions, and comparing with simulation results available in the literature. MD data provide the positions and velocities of all particles needed to compute the dipole moments of the molecule and the surrounding double layer, which are required for the multi-scale simulation of dielectrophoretic phenomena in nanoscopic channels.
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Nanotech 2006 Conference Program Abstract