Dresden 2009 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 17: Poster II

BP 17.15: Poster

Mittwoch, 25. März 2009, 17:15–19:45, P3

Microscopic origins of anomalous diffusion - insights from studies on crowded solutions — •Jedrzej Szymanski and Matthias Weiss — Deutsches Krebsforschungszentrum, Heidelberg, Germany

Subdiffusive motion of macromolecules has been observed in many crowded environments, ranging from polymer and protein solutions to intracellular fluids. A clear understanding of the microscopic origin of the subdiffusive motion, however, has been lacking. To address this point, we have used fluorescence correlation spectroscopy (FCS) to study the diffusion of tracer molecules in crowded solutions with varying composition. We combined this approach with model simulations on percolation-like motion and continuous time random walks (CTRWs). Aiming at discriminating these two fundamentally different processes that may underlie the observed anomalous diffusion in FCS, we compared the experimentally determined distributions of the anomaly degree and the apparent mobility with the simulation data. As a result, the experimental data for crowding-induced subdiffusion are most consistent with a percolation-like motion but deviate strongly from the predictions of a CTRW. Hence, subdiffusion in crowded media, e.g. in the cytoplasm of living cells, most likely arises due to a stochastic process with a Gaussian-like propagator.