(256a) Probing Nano-Domains in Single Bilayer Bio-Membranes Using Grazing Incidence X-Ray Diffraction

In this paper we report the first grazing incidence x-ray diffraction (GIXD) measurements of single phospholipid membranes, composed of two lipid monolayers, at the solid-liquid interface. Previously, GIXD of lipid membranes was confined to the study of amphiphilic monolayers at the liquid-air interface and multilayer membrane stacks in humid environments. Our results reveal that lipid composition has a significant effect on whether a membrane has domains that are coupled between lipid leaflets. Other structural details of single bilayers such as intermolecular spacing of lipid molecules, membrane thickness, and comparisons to related monolayer studies are reported. We believe that the method presented in this paper can be easily implemented to study more complicated and biologically relevant systems and can become a standard method in probing bio-membrane structure and its interaction with proteins.