Campus Units

Physics and Astronomy, Bioinformatics and Computational Biology

Document Type

Article

Publication Version

Published Version

Publication Date

2009

Journal or Book Title

Journal of Chemical Physics

Volume

131

Issue

18

First Page

185102

DOI

10.1063/1.3257735

Abstract

We introduce a minimal free energy describing the interaction of charged groups and counterions including both classical electrostatic and specific interactions. The predictions of the model are compared against the standard model for describing ions next to charged interfaces, consisting of Poisson–Boltzmann theory with additional constants describing ion binding, which are specific to the counterion and the interfacial charge (“chemical binding”). It is shown that the “chemical” model can be appropriately described by an underlying “physical” model over several decades in concentration, but the extracted binding constants are not uniquely defined, as they differ depending on the particular observable quantity being studied. It is also shown that electrostatic correlations for divalent (or higher valence) ions enhance the surface charge by increasing deprotonation, an effect not properly accounted within chemical models. The charged phospholipid phosphatidylserine is analyzed as a concrete example with good agreement with experimental results. We conclude with a detailed discussion on the limitations of chemical or physical models for describing the rich phenomenology of charged interfaces in aqueous media and its relevance to different systems with a particular emphasis on phospholipids.

Comments

The following article appeared in J. Chem. Phys. 131, 185102 (2009); and may be found at http://dx.doi.org/10.1063/1.3257735.

Rights

Copyright 2009 AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing.

Language

en

File Format

application/pdf

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