Dresden 2003 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

CPP: Chemische Physik und Polymerphysik

CPP 21: POSTER B

CPP 21.1: Poster

Dienstag, 25. März 2003, 19:00–21:00, ZEU/250

Active Networks Studied by Magnetic Tweezers Microrheometry and Torsional Macrorheometry — •R. Tharmann, M. Keller, J. Uhde, and A. R. Bausch — Technische Universität München, James-Franck-Straße 1, Garching, 85747

Although the defining property of polymer networks is their viscoelastic behavior, a microscopic understanding of the underlying mechanisms is still lacking. In biological processes, e.g. the migration of cells, the temporal and spatial regulation of the activation of cross-linkers is very important, yet not understood. Even more importantly, biology uses a huge number of distinct cross-linkers which have different effects on the viscoelastic behavior of biological networks.

One class of cross-linkers are molecular motors such as myosins. Under ATP-rich conditions the molecular motors are active, while in the ATP depleted regime the motors act as passive cross-linkers (rigor mortis). Here we use both the technique of Magnetic Tweezers Microrheometry and Torsional Macrorheometry to study the local and the averaged viscoelastic properties of actin networks which are linked by myosin II and HMM fragments at different ATP concentrations. We show, that in the active state the viscoelastic moduli are reduced in the whole frequency regime compared to a uncross-linked network.