Reduction in Tension and Stiffening of Lipid Membranes in an Electric Field Revealed by X-Ray Scattering.
The effect of ac electric fields on the elasticity of supported lipid bilayers is investigated at the microscopic level using grazing incidence synchrotron x-ray scattering. A strong decrease in the membrane tension up to 1  mN/m and a dramatic increase of its effective rigidity up to 300  k_{B}T are observed for local electric potentials seen by the membrane ≲1  V. The experimental results are analyzed using detailed electrokinetic modeling and nonlinear Poisson-Boltzmann theory. Based on a modeling of the electromagnetic stress, which provides an accurate description of the bilayer separation versus 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 the 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 nanometers length scale in cell membranes with lower tension, and could explain a number of electrically driven processes.
UPR 22/CNRS, Institut Charles Sadron, Université de Strasbourg, 23 rue du Loess, BP 84047 67034 Strasbourg Cedex 2, France.
Arnaud
A
Hemmerle
Institut Laue-Langevin, 71 avenue des Martyrs, BP 156, 38042 Grenoble Cedex, France.
Giovanna
G
Fragneto
Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France.
Jean
J
Daillant
UPR 22/CNRS, Institut Charles Sadron, Université de Strasbourg, 23 rue du Loess, BP 84047 67034 Strasbourg Cedex 2, France.
Thierry
T
Charitat
D002462:Cell Membrane / Q000737:chemistry* / Q000502:physiology; D004548:Elasticity; D008051:Lipid Bilayers; D008563:Membrane Lipids; D011859:Radiography; D014965:X-Rays
D008051:Lipid Bilayers; D008563:Membrane Lipids