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AKB: Biologische Physik

AKB 25: Cell Mechanics I

AKB 25.5: Vortrag

Donnerstag, 30. März 2006, 16:00–16:15, ZEU 260

Active and passive one- and two-particle microrheology in cytosksletal networks — •Daisuke Mizuno, Frederick C. MacKintosh, and Christoph F. Schmidt — Dept. Physics, Vrije Universiteit, Amsterdam, NL

We have developed a microrheology (MR) technique that uses micron sized particles to probe the viscoelastic properties of soft samples on small length scales and with high bandwidth. This can be done passively, by observing the Brownian fluctuations of particles embedded in the medium to be tested, or actively by moving the particle with a known force. One can measure the frequency dependent response of one particle on a force on it, or the response of a second particle to a force on the first. The latter (2-particle MR) makes it possible to get around surface artefacts. One can also measure response by actively moving a particle (n our case with an aousto-optic modulator) and observing the corresponding response. Comparison of active and passive experiments provides a test of the fluctuation-disspation theorem. We demonstrate agreement between the techniques in various samples including actin gels as long as samples are in equilibrium.