Berlin 2012 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 26: Posters: Membranes and Vesicles

BP 26.22: Poster

Donnerstag, 29. März 2012, 17:30–19:30, Poster A

Simulation of vesicles at surfaces - rupture, fusion and spreading — •Marc Fuhrmans and Marcus Müller — Universität Göttingen, Institut für Theoretische Physik, Göttingen, Deutschland

Adsorption of unilamellar vesicles to an attractive surface is a frequently used way to form supported bilayers. Although this approach is known to produce continuous bilayers, the mechanism of their formation and its dependence on factors like surface roughness, membrane tension, lipid composition and vesicle size is poorly understood. Theoretical considerations based on elastic theory predict rupture of the vesicles caused by adsorption-induced deformation with an exposure of the inner membrane. While some experiments support this mechanism, others result in an exclusive exposure of the outer monolayer or an even exposure of both the inner and outer monolayers. In addition, in some experiments a critical vesicle concentration on the surface is required to initiate the condensation of a supported bilayer, suggesting an involvement of neighboring vesicles in the rupture process.

We have used dissipative particle dynamics simulations to assess the different mechanisms of vesicle spreading on attractive surfaces, placing special emphasis on the initial location and subsequent development of the rupture pore. In addition, we have studied fusion of neighboring adsorbed vesicles and the involvement of free bilayer edges in vesicle rupture and membrane condensation. Making use of the universality of lipid-associated phenomena, we employed a solvent-free coarse-grained model, enabling us to cover the relatively large system sizes and time scales necessary to observe these collective processes.