Grazing incidence small angle neutron scattering as a tool to study curved biomembranes on nanostructured surfaces

Sammanfattning: Curvature in lipid-based biomembranes provides compartmentalization in cells and can act as regulator of biological activity in living systems. The study of these biomembranes require novel model systems and new methods. In this work I have used a supported phospholipid bilayer on a hexagonal array of silicon nanowires. The nanowires impose curvature on the supported lipid bilayer and the resulting structure has been investigated with a range of methods. Two main techniques have been used grazing incidence small angle neutron scattering (GISANS) and reflectometry. GISANS revealed the structure and coverage of the lipid bilayer on the nanowires, whereas reflectometry has been used to investigate the lipid bilayer on the flat areas between the nanowires. This makes the two techniques complementary, and the same bilayer has been studied on two different surfaces. In addition, confocal microscopy on fluorescently labeled lipids verified the formation of a lipid bilayer on the nanowire surface. Using fluorescence recovery after photobleaching (FRAP), I was able to verify that the formed lipid bilayer was continuous and mobile. To analyze the GISANS data a new method has been developed, which is based on the ratios of integrated peak intensities. These ratios were then compared with ratios of model-calculated form factors. This approach simplifies the analysis of the data, and allows for information on the lipid layer to be obtained directly.

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