Electrostatics of phosphatidic acid monolayers: Insights from computer simulations

TitleElectrostatics of phosphatidic acid monolayers: Insights from computer simulations
Publication TypeJournal Article
Year of Publication2007
AuthorsFaraudo J, Travesset A
Journal TitleColloids and Surfaces a-Physicochemical and Engineering Aspects
Date PublishedJun
Type of ArticleProceedings Paper
ISBN Number0927-7757
Accession NumberISI:000246748500005
Keywordsamphiphilic monolayers, CHARGE, charged interfaces, dielectric overscreening, FORCE-FIELD, interfacial water, inversion, ion correlations, MEMBRANES, molecular dynamics simulations

In this paper, we argue that many of the fascinating electrostatic effects that take place in amphiphilic systems are strongly related to the particular organization of the oxygen atoms within each individual molecule. In particular, we focus on two effects: charge inversion and dielectric overscreening. For that Purpose, we present molecular dynamics simulations of phosphatidic acid (DMPA(2-)) in the presence of divalent counterions. Our results show that the many oxygens present in DMPA(2-) cooperatively create strong binding sites for counterions, which in some cases lead to charge inversion. We also present an analysis of the role of interfacial water and relate our analysis to the phenomenon of dielectric overscreening. Several experimental implications are discussed in the conclusions. (C) 2007 Elsevier B.V. All rights reserved.

Alternate JournalColloid Surf. A-Physicochem. Eng. Asp.