Berlin 2012 – scientific programme

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BP: Fachverband Biologische Physik

BP 14: Membranes and Vesicles

BP 14.1: Topical Talk

Wednesday, March 28, 2012, 09:30–10:00, H 1028

Membrane transformations in vesicles enclosing aqueous two-phase polymer solutions — •Rumiana Dimova — Max Planck Institute of Colloids and Interfaces, Potsdam, Germany

The interior of living cells is crowded with macromolecules. In such a concentrated environment, local phase separation may occur, involving local composition differences and microcompartmentation. Recently, giant vesicles loaded with polymer solutions were reported to exhibit spatial compartments formed by phase separation within the vesicle. We employed these artificial cell systems to study various phenomena related to molecular crowding and microcompartmentation in cells. We demonstrate that similarly to the wetting behavior of liquid droplets in contact with surfaces, different polymer aqueous phases in contact with membranes as a substrate can undergo complete to partial wetting transition (J Am Chem Soc, 2008, 130:12252). We find that the degree of wetting is characterized by a hidden material parameter - the intrinsic contact angle, which can be determined from effective contact angles observed by optical microscopy (Phys Rev Lett, 2009, 103:238103). Upon osmotic deflation of vesicles enclosing two aqueous phases that partially wet the membrane, one can observe vesicle budding and/or tube formation (Proc Natl Acad Sci USA, 2011, 108:4731) depending on the competition between the spontaneous curvature of the membrane and the wetting properties of the aqueous phases. Phase separation of aqueous polymer solutions in vesicles can lead to stable and retractable membrane nanotubes, which is relevant for membrane area storing and regulation in cells.