Membrane-substrate interface: phospholipid bilayers at chemically and topographically structured surfaces

The surface-assisted fusion, rupture, and spreading of vesicles and hydration-induced spreading of lipids onto chemically and topographically structured surfaces gives rise to lipid structures useful for modeling many physical-chemical properties of lipid bilayers. Chemically structured surfaces produce a lipid structure revealing template-induced assembly of coexisting lipid phases, which reflect the underlying pattern of surface energy, wettability, and chemistry. In a construct derived using photochemically patterned molecular monolayers, the author found a spontaneous separation of fluid bilayer regions from the fluid monolayer regions by a controllable transition region or moat. The coexisting bilayer/monolayer morphologies derived from single vesicular sources are particularly attractive for the study of a range of leaflet-dependent biophysical phenomena and offer a new self-assembly strategy for synthesizing large-scale arrays of functional bilayer specific substructures including ion-channels and membrane-proteins. The uses of topologically patterned surfaces similarly provide new models to design complex three-dimensional membrane topographies and curvatures. These platforms promise fundamental biophysical studies of curvature-dependent membrane processes as well as useful bioanalytical devices for molecular separations within fluid amphiphilic membrane environments. Some future directions enabled by lipid self-assembly at structured surfaces are also discussed.