Surface energy of phospholipid bilayers and the correlation to their hydration.

Supported lipid bilayers (SLBs) were prepared on glass and silicon slides grafted with polyethylene glycol (PEG) and covalently bound cholesteryl anchors to fix the lipid bilayer on the surface. Phospholipid bilayers and bilayers modified by addition of covalently bound PEG were investigated. Using contact angle measurements, the surface energy components of bilayer surfaces were analyzed using van Oss' and Owens-Wendt's methods.

Asymmetric or symmetric bilayer formation during oblique drop impact depends on rheological properties of saturated and unsaturated lipid monolayers.

Bilayer structures are formed by approaching two liquid surfaces with phospholipid monolayers, which are brought into contact by oblique drop impact on a liquid surface. Asymmetric bilayers can be produced by the coupling of drop and target monolayers. In contrast, symmetric bilayers or multilayers are formed by collapse of the compressed target monolayer.

Surface rheology and phase transitions of monolayers of phospholipid/cholesterol mixtures.

The dynamic surface elasticity and the surface dilational viscosity of three binary phospholipid/cholesterol mixtures were determined with axisymmetric drop shape analysis on a harmonically oscillating pendent drop. Dipalmitoylphosphatidylcholine, dimyristoylphosphatidylcholine, and dioleoylphosphatidylcholine were used to explore the rheological properties and phase transitions of mixtures of saturated and unsaturated phospholipids with cholesterol. The growth rates for surface dilational viscosity and dynamic elasticity are parallel for all film pressures studied.