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Theses

Dynamique des bicouches lipidiques supportées

Abstract : During this thesis, we have investigated the lateral mobility of pospholipids in supported lipid bilayers on solid substrates. Using the technique of Fluorescence Recovery After Patterned Photobleaching (FRAPP), we display different diffusive behaviors depending on the substrate nature (roughness, chemistry), the phospholipid type and the preparation method of the bilayer. Measuring the diffusion coefficient versus temperature allows us to establish a solid and repeteable set of data concerning the phase transition of such systems and understand the involved mecanisms. Depending of the nature of the substrate, we observe two different behaviors : on glass, both leaflets of the bilayer have the same dynamics indicating that the transition is coupled ; on mica, the proximal leaflet diffuses slowly than the distal one, the latter having almost no interaction with the substrate. The way of preparation is a crucial parameter which shows a greater dispersion of the diffusion measurements using bilayers from vesicles fusion with respect to Langmuir-Blodgett / Langmuir-Schaeffer techniques that engender more homogeneous samples. We also determine activation energies of the different phases and the transition enthalpies of both used phospholipids. This work represents a fundamental stage for the comprehension of diffusive mecanisms of more complex systems such as lipid mixture containing membrane proteins.
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Submitted on : Monday, January 7, 2008 - 4:22:36 PM
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Carole Scomparin. Dynamique des bicouches lipidiques supportées. Physique [physics]. Université de la Méditerranée - Aix-Marseille II, 2007. Français. ⟨tel-00202669⟩

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