Mechanical Engineering Department Seminar
11:00 AM Friday, February 6, 2009 in room 245,
Refreshments served at 10:45
Dr. Matthias F. Schneider
Biological Physics, University of Augsburg
Imagine you rinse your dishes and everything keeps sticking harder. What looks like a drama for your kitchen is a prerequisite for us to survive. During blood clotting it was found that an increasing shear rate triggers an increase in adhesion of blood platelets? A phenomenon in clear contradiction to our daily experience, but crucial for life, since mechanical vessel damage by elevated shear rates is taking place at all times and almost everywhere in our body.
Using acoustic driven microfluidics we mimic our circulatory system and show that the protein von Willebrand factor goes through a reversible global-stretched transition which represents its haemostatic inactive-active state [1,2]. Thus understanding the nonlinear behaviour of this protein unravels the initial steps of blood clotting leaving the counterintuitive picture behind.
Another, well known, nonlinear transition in biological physics is the phase transition of lipid membranes. I will present a variety of experiments where material properties and therefore morphology, sound propagation and ion conduction are directly coupled to the thermodynamics of the system. The observed phenomena reveal an exceptional similarity with biological processes.
Considering the fact that the biological membrane is heterogeneous a state of coexistence (like the transition regime) seems to resemble the physical properties of biomembranes much more realistic then a pure fluid membrane, which failed to explain cellular membranes.