Regensburg 2016 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 57: Membranes and Vesicles I
BP 57.3: Vortrag
Donnerstag, 10. März 2016, 10:15–10:30, H43
Squeezing vesicles on a supported lipid bilayer using osmolyte polymer chains: a neutron reflectivity study — •Alexandros Koutsioumpas1 and Didier Lairez2 — 1Jülich Centre for Neutron Science (JCNS), Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstrasse 1, 85747 Garching, Germany — 2Laboratoire Léon Brillouin, CEA/CNRS UMR 12, CEA-Saclay, 91191 Gif-sur-Yvette, France
The approach of two lipid bilayer segments in close proximity is an event of special interest in biophysics, due to its relation with several biological functions such as membrane fusion. Using the neutron reflectometry technique we attempt to gather structural information related to the interaction of a planar supported DPPC bilayer with DPPC vesicles that are "forced" at the interface by the addition of high concentrations of polyethylene glycol chains in bulk solution. At the adopted experimental conditions the major effect that is observed is related to the initial approach of vesicles close to the supported bilayer at temperatures below the liquid/gel transition, followed by their "spreading" and flattening at temperatures above the transition that is attributed to the radical decrease of their bending modulus. The experimental observation is backed up by semi-analytic calculations based on the Helfrich Hamiltonian that describes membrane mechanics. In all cases, no indication of any pre-fusion structure is found. These observations are also discussed in the context of alternative potential approaches for the formation of floating bilayers on a planar surface.