Reduction in Tension and Stiffening of Lipid Membranes in an Electric Field Revealed by X-ray Scattering

TL;DR

This study reveals how AC electric fields significantly reduce tension and increase rigidity in lipid membranes, potentially affecting membrane stability and related biological processes.

Contribution

It provides a detailed microscopic analysis of electric field effects on lipid bilayer elasticity using advanced X-ray scattering and electrokinetic modeling.

Findings

Membrane tension decreases up to 1mN/m under electric fields.

Effective membrane rigidity increases up to 300kBT.

Electric double layer interactions destabilize bilayers.

Abstract

The effect of AC electric fields on the elasticity of supported lipid bilayers has been investigated at the microscopic level using grazing incidence synchrotron x-ray scattering. A strong decrease in the membrane tension up to 1mN/m and a dramatic increase of its effective rigidity up to 300kBT are observed for local electric potentials seen by the membrane < 1V. The experimental results were analyzed using detailed electrokinetic modeling and non-linear Poisson-Boltzmann theory. Based on a modeling of the electromagnetic stress which provides an accurate description of bilayer separation vs pressure curves, we show that the decrease in tension results from the amplification of charge fluctuations on the membrane surface whereas the increase in bending rigidity results from direct interaction between charges in the electric double layer. These effects eventually lead to a destabilization of the bilayer and vesicle formation. Similar effects are expected at the tens of nanometer lengthscale in cell membranes with lower tension, and could explain a number of electrically driven processes.