SKM 2023 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 56: Brownian Motion and Anomalous Diffusion

DY 56.11: Vortrag

Freitag, 31. März 2023, 12:30–12:45, ZEU 160

Bio-hybrid colloidal transport of beads on cell monolayers — Lara Bort, Setareh Sharifi Panah, •Robert Großmann, and Carsten Beta — Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany

The erratic motion of Brownian particles at the mesoscale, driven by collisions with the surrounding fluid particles, is the paradigm of random colloidal transport within a passive environment. In this work, we describe the transport of polystyrene micro-beads whose motion is driven by a monolayer of motile cells. We use cells of the social amoeba Dictyostelium discoideum, which is a widely used model organism for actin-driven motility of adherent eukaryotic cells, including neutrophils and cancer cells. Given the non-specific adhesion of our model organism, the binding of such micro-cargo to the cell membrane does not require any surface-functionalization – the physical link between cargo and carrier is established spontaneously. As a particle gets in contact with a cell, it adheres to the cell membrane and is then subjected to active forces exerted by cells. The dynamics of micro-beads reveals linear scaling of the ensemble-averaged mean-square displacement and, notably, non-Gaussian displacement distributions. We rationalize these findings by assuming that each colloidal particle effectively performs normal Brownian motion, but the diffusion coefficients vary within the ensemble due to cell-to-cell variability. This superstatistics allows to reproduce the statistical features of the long-time dynamics of colloids, subject to the active cellular forces. It serves as a first step to better understand the targeted transport of foreign objects in dense tissues.