Regensburg 2007 – scientific programme

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BP: Fachverband Biologische Physik

BP 26: Poster Session II

BP 26.36: Poster

Thursday, March 29, 2007, 17:00–19:30, Poster B

In-situ real-time observation of single giant unilamellar vesicle phase behavior under rapid variation of the medium — •Philipp Rauch, Florian Rückerl, Josef Käs, and Carsten Selle — Inst. f. experimentelle Physik, Physik der weichen Materie,Universität Leipzig, Germany

Giant unilamellar vesicles (GUVs) are frequently used as model systems for intracellular and plasma membranes. Phase inhomogeneity corresponding to the appearance of microdomains in biological membranes was postulated to play a key role in triggering and controlling of various intra- and intercellular events like signal processing and absorption or adhesion of foreign matter. The investigation of the phase behavior of lipid systems showing coexistence of two liquid phases at physiological temperatures has moved into the focus of membrane physics. Related temperature-induced phase transitions have been observed and well described since they are easy to follow by fluorescent microscopy (FM) and calorimetry methods. We built a microfluidic flow chamber setup that allows us to manipulate single GUVs via optical tweezers while exposing them to varied media. The dynamics of phase alterations induced by jump-like change of the aqueous medium can be recorded in real-time. We investigated changes induced by increasing pH or ion strength of the surrounding. Our setup provides a compact method to manipulate single GUVs while examining alterations in lipid phase behavior due to arbitrarily modified media. Potentially, data can be obtained allowing conclusions on the role of lipid membranes in the interplay of components in living cells.