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Updated: Aug 16, 2026

Realistic Membrane Modeling Using Complex Lipid Mixtures in Simulation Studies
Published on: September 1, 2023
Structure and fluctuations of a single floating lipid bilayer
J Daillant1, E Bellet-Amalric, A Braslau
1Service de Chimie Moléculaire/LIONS, Commissariat à l'Energie Atomique Saclay, Bâtiment 125, F-91191 Gif-sur-Yvette Cedex, France. daillant@dsm-mail.saclay.cea.fr
Abstract:
A single lipid molecular bilayer of 17 or 18 carbon chain phosphocholines, floating in water near a flat wall, is prepared in the bilayer gel phase and then heated to the fluid phase. Its structure (electron density profile) and height fluctuations are determined by using x-ray reflectivity and non-specular scattering. By fitting the off-specular signal to that calculated for a two-dimensional membrane using a Helfrich Hamiltonian, we determine the three main physical quantities that govern the bilayer height fluctuations: The wall attraction potential is unexpectedly low; the surface tension, roughly independent on chain length and temperature, is moderate (approximately 5 x 10(-4) J.m(-2)) but large enough to dominate the intermediate range of the fluctuation spectrum; and the bending modulus abruptly decreases by an order-of-magnitude from 10(-18) J to 10(-19) J at the bilayer gel-to-fluid transition.
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