Electroporation of curved lipid membranes in ionic strength gradients

A thermodynamic theory for the membrane electroporation of curved membranes such as those of lipid vesicles and cylindrical membrane tubes has been de veloped. The theory covers in particular the observation that electric pore formation and shape deformation of vesicles and cells are dependent on the salt concentration of the suspending solvent. It is shown that transmembra ne salt gradients can appreciably modify the electrostatic part of Helfrich 's spontaneous curvature, elastic bending rigidity and Gaussian curvature m odulus of charged membranes. The Gibbs reaction energy of membrane electrop oration can be explicitely expressed in terms of salt gradient-dependent co ntributions of bending, the ionic double layers and electric surface potent ials and dielectric polarisation of aqueous pores. In order to cover the va rious physical contribution to the chemical process of electroporation-rese aling, we have introduced a generalised chemophysical potential covering al l generalised forces and generalised displacements in terms of a transforme d Gibbs energy formalism. Comparison with, and analysis of, the data of ele ctrooptical relaxation kinetic studies show that the Gibbs reaction energy terms can be directly determined from turbidity dichroism (Planck's conserv ative dichroism). The approach also quantifies the electroporative cross-me mbrane material exchange such as electrolyte release, electrohaemolysis of red blood cells or uptake of drugs and dyes and finally gene DNA by membran e electroporation. (C) 2000 Elsevier Science B.V. All rights reserved.