Electrophoresis of a rod macroion under polyelectrolyte salt: is mobility reversed forDNA?

Abstract

By molecular dynamics simulation, we study the charge inversion phenomenon of a rodmacroion in the presence of polyelectrolyte counterions. We simulate electrophoresis of themacroion under an applied electric field. When both counterions and coions arepolyelectrolytes, charge inversion occurs if the line charge density of the counterions islarger than that of the coions. For the macroion of surface charge density equal to that ofthe DNA, the reversed mobility is realized either with adsorption of the multivalentcounterion polyelectrolyte or the combination of electrostatics and other mechanismsincluding the short-range attraction potential or the mechanical twinning of polyelectrolytearound the rod axis.