Berlin 2012 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 26: Posters: Membranes and Vesicles
BP 26.21: Poster
Donnerstag, 29. März 2012, 17:30–19:30, Poster A
Influence of charge density on bilayer bending rigidity in lipid vesicles: a combined dynamic light scattering and neutron spin-echo study — •Beate-Annette Brüning1, Ralf Stehle1,2, Peter Falus3, and Bela Farago3 — 1Helmholtz Zentrum Berlin, Hahn-Meitner Platz 1, 14109 Berlin, Germany — 2Universität Bayreuth, Postfach 10 12 51, 95440 Bayreuth, Germany — 3Institut Laue-Langevin, B.P. 156, 6 rue Jules Horowitz, 38042 Grenoble, France
We report a combined dynamic light scattering and neutron spin-echo study on vesicles composed of the uncharged helper lipid DMPC and the cationic lipid DOTAP. Mechanical properties of a model membrane and the corresponding fluctuation dynamics can be tuned by changing composition. We compare the bilayer undulation dynamics in lipid vesicles composed of DMPC/DOTAP to vesicles composed of DMPC and the also uncharged reference lipid DOPC. We find, that on the local scale, lipid headgroup composition and charge change the vesicle fluctuations less than acyl chain packing inhomogenities between the composite lipids. We discuss this result on the basis of domain formation in the lipid mixtures containing charged (DMPC/DOTAP) and uncharged reference lipid (DMPC/DOPC). First, we investigate lipid vesicle size and mass diffusion using dynamic light scattering, then we study collective bilayer undulations and bulk diffusion on two distinct time scales around 25ns and 150ns, using neutron spin-echo spectroscopy. Finally, we estimate bilayer bending rigidities κB for the charged and uncharged lipid vesicles.