Titratable macroions in multivalent electrolyte solutions: Strong coupling dressed ion approach

Abstract

We present a theoretical description of the effect of polyvalent ions on the interaction between titratable macro-ions. The model system consists of two point-like macro-ions with dissociable sites, immersed in an asymmetric ionic mixture of monovalent and polyvalent salts. We formulate a dressed ion strong coupling theory, based on the decomposition of the asymmetric ionic mixture into a weakly electrostatically coupled monovalent salt, and into polyvalent ions that are strongly electrostatically coupled to the titratable macro-ions. The charge of the macroions is not considered as fixed, but is allowed to respond to local bathing solution parameters (electrostatic potential, pH of the solution, salt concentration) through a simple charge regulation model. The approach presented, yielding an effective polyvalent-ion mediated interaction between charge-regulated macro-ions at various solution conditions, describes the strong coupling equivalent of the Kirkwood-Schumaker interaction.

Effective Repulsion Between Oppositely Charged Particles in Symmetrical Multivalent Salt Solutions: Effect of Salt Valence

“…Our present work also involved some important simplifications. First, the model system with solvent and particles was modeled as uniform dielectric medium of high dielectric constant, and consequently, the dielectric boundary between particles and solvent was ignored [78][79][80]. Second, the charges of particles were placed at the centers of particle spheres, and the discreteness of charges on the particle surface was not involved in the work.…”

Competitive sorption of mono- versus di-valent ions by highly charged globular macromolecules

“…Interactions of multivalent ions with polyelectrolyte solutions have been theoretically studied in the past, in terms of their thermodynamic properties, 90 ionic and potential distributions, 91 accurate calculation of the effective charge, 92 and the effect on the interaction between polyelectrolyte macromolecules. [93][94][95][96] In this paper, the focus is to theoretically analyze the competitive sorption of mono-versus divalent counterions by highly charged spherical dPGS-like polyelectrolytes with the help of mean-field continuum and discrete binding site models, informed by coarse-grained computer simulations of dPGS of various generations. The theoretical models are generally formulated for globular charged macromolecules and include ion-specific effects in a parametric way and can thus be straightforwardly modified or adapted to other charged globules, where mono-/divalent ionexchange plays a role.…”