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AKB: Biologische Physik
AKB 10: Cytoskeleton and Polymer Networks
AKB 10.1: Hauptvortrag
Montag, 8. März 2004, 09:30–10:00, H40
Micromechanics of Biopolymer Networks and Shells — •Christoph F. Schmidt1, Maryam Atakhorrami1, Gijsberta H. Koenderink1, Pedro J. de Pablo2, Iwan A.T. Schaap1, Irena L. Ivanovska1, Gijs J.L. Wuite1, and Frederick C. MacKintosh1 — 1Vrije Universiteit Amsterdam, Dept. Physics, De Boelelaan 1081, — 2Universidad Autonoma de Madrid, Departamento de Fisica de la
Polymeric macromolecular assemblies play crucial roles in biology, from DNA to the cytoskeleton or the cell membrane. We are generally interested in the mechanical physical properties of such structures and in their interactions with force generating motor proteins. I will report here on measurements of the viscoelastic properties of model 3D actin networks by microrheology and on measurements of the elastic properties of two types of 2D-crystalline protein shells, microtubules and bacteriophage capsids, probed by indentation with a scanning force microscope. Actin networks are determining cell elastic response and we have probed their complex viscoelastic response over a large range of length and time scales, under a variety of conditions approaching those found in cells. Both, microtubules and viral capsids are 2D protein shells and we found linear elastic regimes that can be described by thin-shell theory and finite element methods. We also found non-linear regimes and catastrophic collapse under large loads. The mechanical response of these protein shells at the nanometer scale shows simultaneously aspects of continuum elasticity, as well as molecular graininess, particularly in their non-linear behavior.