Dresden 2006 – scientific programme

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AKB: Biologische Physik

AKB 25: Cell Mechanics I

AKB 25.3: Talk

Thursday, March 30, 2006, 15:30–15:45, ZEU 260

Nonlinear mechanical properties of entangled and cross linked actin networks — •Christine Semmrich, Rainer Tharmann, Bernd Wagner, and Andreas R. Bausch — Lehrstuhl für Biophysik E22, Physik-Department, Technische Universität München,D-85747 Garching, Deutschland

The mechanical response of cells is predominantly determined by the actin cytoskeleton. The nonlinear behaviour of crosslinked network show a pronounced dependence on the applied stresses spanning orders of magnitude in their elastic response. This can be related to the nonlinear mechanical behaviour of single filaments of this semiflexible polymer. In contrast, for purely entangled networks a tube model describes the mechanical response and thus no strain hardening is expected. By means of different rheological approaches we are able to investigate the nonlinear response of purely entangled actin networks. Interestingly, under standard conditions a strain hardening at temperatures below 23^∘C is observed. Highering the temperature, a strain softening occurs. The temperature dependence of the nonlinear behaviour is also highly dependent on the buffer salt concentration. This suggests that the interaction potential between filaments plays an important role for the observed behaviour. We discuss these results within theoretical predictions of entangled and crosslinked networks.