Dresden 2006 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
AKB: Biologische Physik
AKB 40: Poster Session II
AKB 40.23: Poster
Mittwoch, 29. März 2006, 16:30–19:30, P3
Cell rheology at high stress — •Philip Kollmannsberger, Johannes Pauli, Claudia Mierke, Carina Raupach, and Ben Fabry — Zentrum für Medizinische Physik und Technik, Henkestr. 91, 91054 Erlangen
Rheology measurements in many cell types have established that cells exhibit a power-law creep modulus, or equivalently, a weak frequency dependence of the storage and loss moduli according to a power-law. These findings indicate that cell rheology is governed by multiple processes that play out on vastly different time scales. Previous measurements, however, where carried out in the linear regime, where stress and strain are related by a simple linear relationship, and the superposition principle holds. Here we measured the displacement of CSK-bound superparamagnetic beads in a feedback-controlled magnetic field gradient at high forces up to > 10 nN for which linearity, superposition and time scale free behavior of responses have not been established. At all forces, bead displacement d during during the on-phase (creep) and off-phase (relaxation) was well described by a power law: d(t) = a·(t/t0)b. For forces less than 2 nN, power-law parameters during creep and recovery were identical. At higher forces, however, the recovery became progressively incomplete (a decreased) and faster (b increased). These results suggest that at higher forces, stable, long-lived stress-bearing structures within the cytoskeleton are disrupted. Subsequent structural rearrangements are then expected to contribute to a speed-up of relaxation processes.