Control of the structure of self-spreading lipid membrane by changing electrolyte concentration

We have controlled the structure of self-spreading lipid bilayer membranes prepared on surface-oxidized silicon substrates by changing electrolyte concentration. Analysis of the fluorescence intensity, considering the optical interference effect, clarified the stacking structure of the lipid membrane. By varying the electrolyte concentration, we can vary the number of single multilamellar lobes adsorbed on the underlying self-spreading bilayer. This dependence of the stacking ability on the electrolyte concentration was investigated on the basis of changes in the bilayer-lobe interaction energies, including van der Waals, electrostatic double layer, and hydration interaction energies. Theoretical estimation suggests that the observed electrolyte concentration dependence can be explained by the combination of the van der Waals attractive interaction energy and the repulsive double-layer interaction energy.