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Critical polyelectrolyte adsorption under confinement: Planar slit, cylindrical pore, and spherical cavity

Authors

  • A. G. Cherstvy

    Corresponding author
    1. Institute of Complex Systems, ICS-2, Forschungszentrum Jülich, 52425 Jülich, Germany
    2. Institute for Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany
    3. MPI for Physics of Complex Systems, Nöthnitzerstr. 38, 01187 Dresden, Germany
    • Institute of Complex Systems, ICS-2, Forschungszentrum Jülich, 52425 Jülich, Germany
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  • This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley. com

Abstract

We explore the properties of adsorption of flexible polyelectrolyte chains in confined spaces between the oppositely charged surfaces in three basic geometries. A method of approximate uniformly valid solutions for the Green function equation for the eigenfunctions of polymer density distributions is developed to rationalize the critical adsorption conditions. The same approach was implemented in our recent study for the “inverse” problem of polyelectrolyte adsorption onto a planar surface, and on the outer surface of rod-like and spherical obstacles. For the three adsorption geometries investigated, the theory yields simple scaling relations for the minimal surface charge density that triggers the chain adsorption, as a function of the Debye screening length and surface curvature. The encapsulation of polyelectrolytes is governed by interplay of the electrostatic attraction energy toward the adsorbing surface and entropic repulsion of the chain squeezed into a thin slit or small cavities. Under the conditions of surface-mediated confinement, substantially larger polymer linear charge densities are required to adsorb a polyelectrolyte inside a charged spherical cavity, relative to a cylindrical pore and to a planar slit (at the same interfacial surface charge density). Possible biological implications are discussed briefly in the end. © 2012 Wiley Periodicals, Inc. Biopolymers 97: 311–317, 2012.

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