Characterization of Floating Surface Layers of Lipids and Lipopolymers by Surface-Sensitive Scattering

Abstract

Nanotechnology and molecular (bio-)engineering are making ever deepening inroads into everybody's daily life. Physicochemical and biotechnological achievements in the design of physiologically active supramolecular assemblies have brought about the quest for their submolecular-level characterization. We employ surface-sensitive scattering techniques for the investigation of planar lipid membranes-floating monolayers on aqueous surfaces-to correlate structural, functional and dynamic aspects of biomembrane models. This chapter surveys recent work on the submolecular structure of floating phospholipid monolayers-where the advent of third-generation synchrotron X-ray sources has driven the development of realistic, submolecular-scale quasi-chemical models-as well as of more complex systems: cation binding to anionic lipid surfaces; conformational changes of lipopolymers undergoing phase transitions; the conformational organization of phosphatidylinositol and phosphatidylinositides, as examples of physiologically important lipids; and the adsorption of peptides (neuropeptide Y, NPY) or solvents (dimethylsulfoxide, DMSO) onto phospho-lipid surface layers.