Regensburg 2013 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 18: Membranes and Vesicles I

BP 18.3: Vortrag

Mittwoch, 13. März 2013, 10:15–10:30, H44

Quantitative understanding of the nonspecific vesicle-substrate adhesion — •Daniel Schmidt¹, Udo Seifert¹, and Ana-Sunčana Smith² — ¹II. Institut für Theoretische Physik, Universität Stuttgart — ²Institut für Theoretische Physik and Excellence Cluster: Engineering of Advanced Materials, Universität Erlangen-Nürnberg

Phospholipid membranes in cellular and biomimetic systems exhibit significant thermal fluctuations. These fluctuations play an important role in the regulatory mechanisms of the cell recognition process, when a cell binds to another cell membrane or, as in biomimetic systems, to a rigid substrate. The presence of such a substrate is manifested by the emergence of a non-specific potential, the strength of which is coupled to the membrane tension. The latter in turn affects the fluctuations in a fashion that is not fully understood.

Here we develop a procedure for the accurate determination of the membrane tension and the strength of the non-specific potential from experimental data, independent of the choice of the measurable - the membrane shape, the spatial or the temporal correlation functions. We achieve this goal after overcoming the limitations of the typically used, harmonic approximation of the potential. Additionally, we extract the true fluctuations from the apparent ones, which are modified due to the finite temporal and spatial resolution in microscopy. As a result, we obtain the first coherent view of the behavior of the membrane in a vicinity of a substrate, in a system that is of a finite size and away from the unbinding transition.