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CP: Chemische Physik

CP 30: Poster: Biologische Systeme

CP 30.3: Poster

Monday, March 22, 1999, 18:00–20:00, R52/R72

Microrheology of Membranes — •L. Xu and H.-G. Döbereiner — Max-Planck-Institut für Kolloid- und Grenzflächenforschung,
Kantstrasse 55, 14513 Teltow-Seehof

We present a fully computer-controlled setup for micromanipulation of giant vesicles with opposing micropipettes under a phase contrast microscope. Control of pipette position and/or suction pressure is integrated with real-time image analysis of vesicle response to application of bilayer stress. Repeating a particular experiment on the same vesicle automatically a large number of times allows to measure membrane material parameters with a small statistical error. We study dynamical membrane behavior in the entropic tension regime with well-defined boundary conditions. Tubular vesicles hold at their poles respond to pushing and pulling stresses with a buckling and spindle instability, respectively. Observations of spindle movements along cone-like tethers provide information on microrheological properties of membranes. Various dissipative mechanism, including bulk water and bilayer lipid viscous flow, as well as inter-monolayer drag can be studied.