Dresden 2011 – scientific programme

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BP: Fachverband Biologische Physik

BP 13: Posters: Biological Membranes

BP 13.16: Poster

Monday, March 14, 2011, 17:15–20:00, P3

Phase separation and near-critical fluctuations in two-component lipid membranes: Monte Carlo simulations on experimentally relevant scales — •Jens Ehrig, Eugene P. Petrov, and Petra Schwille — Biophysics, BIOTEC, TU Dresden, Tatzberg 47/49, 01307 Dresden, Germany

By means of lattice-based Monte Carlo simulations, we address properties of two-component lipid membranes on the experimentally relevant spatial scales of order of a micrometer and time intervals of order of a second, using DMPC/DSPC lipid mixtures as a model system. We find that, within a certain range of lipid compositions, the phase transition from the fluid phase to the fluid-gel phase coexistence proceeds via near-critical fluctuations. The line tension characterizing lipid domains in the fluid-gel coexistence region is found to be ∼ 2 pN. When approaching the critical point, the line tension, the inverse correlation length of fluid-gel spatial fluctuations, and the corresponding inverse order parameter susceptibility of the membrane vanish. All these results are in agreement with recent experimental findings for model lipid membranes. We observe transient subdiffusive behavior of lipids in the presence of near-critical fluctuations, which is a new result important for understanding the origins of subdiffusion in cell membranes. The effects of the interaction of the membrane with the cytoskeleton will be discussed as well.

[1] J. Ehrig, E. P. Petrov, and P. Schwille, Biophys. J. 99 (2010), doi:10.1016/j.bpj.2010.11.002.

[2] J. Ehrig, E. P. Petrov, and P. Schwille, arXiv:1009.4860.