Structure and interaction potentials in solid-supported lipid membranes studied by X-ray reflectivity at varied osmotic pressure

TL;DR

This study investigates the structure and interactions of solid-supported lipid membranes under varying osmotic pressures using X-ray reflectivity, providing insights into bilayer fluctuations and inter-bilayer potentials.

Contribution

It introduces a detailed analysis of lipid membrane fluctuations and potentials using X-ray reflectivity and smectic Hamiltonian modeling under controlled osmotic conditions.

Findings

Quantitative characterization of bilayer fluctuations.

Pressure-distance relation for lipid stacks.

Insights into inter-bilayer potentials.

Abstract

Highly oriented solid-supported lipid membranes in stacks of controlled number $N \simeq 16$ (oligo-membranes) have been prepared by spin-coating using the uncharged lipid model system 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). The samples have been immersed in aqueous polymer solutions for control of osmotic pressure and have been studied by X-ray reflectivity. The bilayer structure and fluctuations have been determined by modelling the data over the full q-range. Thermal fluctuations are described using the continuous smectic Hamiltonian with the appropriate boundary conditions at the substrate and at the free surface of the stack. The resulting fluctuation amplitudes and the pressure-distance relation are discussed in view of the inter-bilayer potential.