Controlled solvent-exchange deposition of phospholipid membranes onto solid surfaces.

Controlled deposition of lipid bilayers plays a key role in creating supported membranes for biosensing devices and biophysical cell studies. The authors adopt a solvent-exchange method in order to deposit a phospholipid bilayer on solid substrates. The basic concept of deposition is to dissolve phospholipids in isopropanol-water mixtures and to increase water content gradually. Shortly before the onset of the micelle-to-vesicle transition, a lipid bilayer nucleates at the solid surface. They investigate the bulk phase behavior and surface coverage using small angle x-ray scattering and attenuated total reflection-Fourier transform infrared spectroscopy. They find a sequence of transitions from inverted-monomeric-micellar and vesicle phases correlating with an increasing amount of lipid on the adsorption layer. Supported lipid bilayers, prepared using this approach, are homogeneous and fluid.