Dresden 2006 – scientific programme

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AKB: Biologische Physik

AKB 40: Poster Session II

AKB 40.50: Poster

Wednesday, March 29, 2006, 16:30–19:30, P3

Shear-dependency of von Willebrand factor measured in hydrodynamic flow and by micro-pipette aspiration technique — •J. Opfer, A. Wixforth, and M. F. Schneider — Universität Augsburg

Von Willebrand factor (vWf) is a biopolymer, which is known to play an important role in hemostasis. Dysfunction entails severe bleeding disorders. Recently it was shown that vWf reactivity is increased by shear stress, which is presumably caused by a coil-fiber transition. On the other hand, a shear-induced loss of efficiency has been found. Hence the correlation between shear forces and vWf effectivity is of great interest.

In order to study this correlation we mimic blood flow using novel designed bio-chips by means of surface acoustic waves (SAW), which are launched into the fluid containing vWf polymers and generate a laminar flow. The method allows sample volumes of only a few microliters, a wide spectrum of flow velocities and the imitation of any physiological relevant geometry.

Besides micro-pipette aspiration technique is applied for measuring homotypic interactions of vWf molecules, which have undergone different shearing forces. Mono-laminar phospholipid vesicles are coated with vWf and exposed to a vWf-covered wall. The vesicle’s deformation reflects the magnitude of adhesive forces mediated by the polymer and permits observing its self-association kinetics.