title: Analytic Model for the Dipole Potential of a Lipid Layer.
abstract: The larger permeability of anions than cations through a lipid bilayer can be rationalized by the positive sign of the bilayer's dipole potential. That is, upon crossing the lipid headgroups toward the hydrocarbon chain region, the electrostatic potential increases by several hundred millivolts. We derive an analytic expression for the dipole potential of a single lipid layer using an electrostatic model that is based on an extended version of the linearized Poisson-Boltzmann theory. The model highlights the ability of the lipid headgroups to render the dipole potential positive by inducing an orientational ordering of the solvent molecules. The positive contribution of the solvent overcompensates the negative dipole potential due to the bare lipids. Our theoretical prediction compares accurately with measurements of the dipole potential that we have conducted for mixed anionic-zwitterionic lipid monolayers at the air-water interface.
authors.affiliation: Faculty of Health Sciences, University of Ljubljana , Zdravstvena 5, SI-1000 Ljubljana, Slovenia.
authors.forename: Klemen
authors.initials: K
authors.lastname: Bohinc
authors.affiliation: BioNanoPlasmonics Lab, CIC biomaGUNE , 20009 Donostia - San Sebastian, Spain.|Department of Physical Chemistry and Applied Thermodynamics, University of Cordoba , Campus de Rabanales, Edificio Marie Curie, Cordoba E-14014, Spain.
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Giner-Casares
authors.affiliation: Department of Physics, North Dakota State University , Fargo, North Dakota 58108-6050, United States.
authors.forename: Sylvio
authors.initials: S
authors.lastname: May