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BP: Fachverband Biologische Physik
BP 8: Poster Session Ia
BP 8.35: Poster
Montag, 18. März 2024, 18:00–20:30, Poster C
Measuring viscoelastic properties in active, living systems through passive observations — •Till M. Muenker1, Gabriel Knotz2, Matthias Krüger2, and Timo Betz1 — 1Third Institute of Physics, Universität Göttingen, Göttingen, Germany — 2Institute of Theoretical Physics, Universität Göttingen, Göttingen, Germany
Accurately quantifying the viscoelastic material properties within active systems, such as cells, poses a challenging task. Due to the non-equilibrium nature of such systems, many powerful tools from statistical physics like the MSD fail to predict material properties from passive observation of a tracer particle. Instead, active methods such as optical- and magnetic tweezers are used where typically external forces are applied to measure the material response. Here, we introduce a new statistical method, termed mean back relaxation (MBR). By quantifying the mean displacement of a probe particle after having transitioned a specific distance in the immediate time history, this new quantity allows to detect breaking of detailed balance in confined systems. Firstly, we test this method in a well-controlled experimental model system where we are able to detect the level of non-equilibrium. Next, we turn to the most complex, but also highly relevant system, living cells. Strikingly, applying this novel approach not only allows us to measure the level of activity but also gives access to the viscoelastic material properties of a range of different cell types. This approach could drastically facilitate the quantification of intracellular mechanics, thus opening the door for many researchers who do not have access to elaborate experimental setups.
Keywords: Cell mechanics; Viscoelasticity; Rheology; Non-equilibrium