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The phenomena of charge inversion and effective attraction between the like - charged spherical macromolecules in electrolyte solvent has been studied by using Poisson - Boltzmann mean-field theory, alongside the assumption that counterions condense on the surface of macromolecules to form a strongly correlation liquid.
42 Ha Noi Metroplolitan University THE PHENOMENA OF CHARGE INVERSION AND EFFECTIVE ATTRACTION BETWEEN THE SPHERICAL MACROMOLECULES IN ELECTROLYTE SOLVENT Nguyen Vu Nhan1, Nguyen Viet Duc2, Toan T Nguyen2 Hanoi Metropolitan University Key Laboratory for Multiscale Simulation of Complex Systems, VNU University of Science, Vietnam National University Abstract: The phenomena of charge inversion and effective attraction between the like charged spherical macromolecules in electrolyte solvent has been studied by using Poisson - Boltzmann mean-field theory, alongside the assumption that counterions condense on the surface of macromolecules to form a strongly correlation liquid This oversimplified model is able to capture many important features of these phenomena, provide essential understanding of electrostatics in strong interaction regime in biological and soft matter systems Keywords: Charge inversion, like-charged attraction, polyelectrolyte solution, Poisson Boltzmann equation, biological macromolecule Email: nvnhan@hnmu.edu.vn Received 16 October 2019 Accepted for publication 15 November 2019 INTRODUCTION In recent years, the there are many researches on physical properties of biological and soft maters macro-molecules, such as colloidal particles, vesicles, micelles, proteins, DNA… Insightly knowledge about structure and also interaction of biological molecules is essential to understand biological processes [1] Most of these systems function in aqueous solution in the presence of many electrolytes such as NaCl, MgCl2… Standard theoretical and computational approaches to understand the electrostatics of these system has been mostly based on the Poisson-Boltzmann self-consistence mean field theory [2] Since this is a mean field theory, its validity is limited to electrolyte solution with weak electrostatic interaction When the counterion concentration in the solution is too large, or the solution contain highly valent ions, there are effects that the mean field theory cannot explain, such 43 Scientific Journal No35/2019 as the effect of the inversion of charges, the like - charge attraction between macromolecules [3] Strongly correlated liquid theory and similar theories have been employed to investigate electrostatics in these systems [3,4] In many cases, one can understand the essential physics by separating the mobile ions into two populations, a condensed counterion population on the surface of macroions which can be treated in the strong interaction limit, and a diffuse counterion population further away into the aqueous solution which can be treated using conventional weak interaction electrostatic theories [3] In this paper, we gave a brief overview of these approaches and applying it to calculate the attraction among spherical macroions in electrolyte solution Our results can contribute to understand electrostatics in microemulsion systems, protein solutions, or other soft matter and biological systems with charged macromolecules BRIEF REVIEW ON POISSON-BOLTZMANN MEAN FIELD THEORY Consider the Poisson equation of electrostatics: (1) in which, is the electric charge density, and is electric field, and are dielectric constant of air and relative dielectric constant of medium (water in our case) equivalently The latter is related to the electrostatic potential by the formula: (2) In electrolyte solution containing ions with valence Z+ and Z-, the electric charge density can be written in the following form: ... No35/2019 as the effect of the inversion of charges, the like - charge attraction between macromolecules [3] Strongly correlated liquid theory and similar theories have been employed to investigate... (water in our case) equivalently The latter is related to the electrostatic potential by the formula: (2) In electrolyte solution containing ions with valence Z+ and Z-, the electric charge density... treated in the strong interaction limit, and a diffuse counterion population further away into the aqueous solution which can be treated using conventional weak interaction electrostatic theories