Electrophoresis of a charge-inverted macroion complex: Molecular-dynamics study

Motohiko Tanaka, A. Yu Grosberg

    Research output: Contribution to journalArticle

    Abstract

    We have performed molecular-dynamics simulations to study the effect of an external electric field on a macroion in the solution of multivalent Z : 1 salt. To obtain plausible hydrodynamics of the medium, we explicitly make the simulation of many neutral particles along with ions. In a weak electric field, the macroion drifts together with the strongly adsorbed multivalent counterions along the electric field, in the direction proving inversion of the charge sign. The reversed mobility of the macroion is insensitive to the external field, and increases with salt ionic strength. The reversed mobility takes a maximal value at intermediate counterion valence. The motion of the macroion complex does not induce any flow of the neutral solvent away from the macroion, which reveals screening of hydrodynamic interactions at short distances in electrolyte solutions. A very large electric field, comparable to the macroion unscreened field, disrupts charge inversion by stripping the adsorbed counterions off the macroion.

    Original languageEnglish (US)
    Pages (from-to)371-379
    Number of pages9
    JournalEuropean Physical Journal E
    Volume7
    Issue number4
    DOIs
    StatePublished - Apr 2002

    ASJC Scopus subject areas

    • Biotechnology
    • Biophysics
    • Chemistry(all)
    • Materials Science(all)
    • Surfaces and Interfaces

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