Regensburg 2019 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 14: Cell mechanics I

BP 14.3: Vortrag

Mittwoch, 3. April 2019, 10:00–10:15, H10

Measuring cellular reactions upon particle approach on a broad bandwidth by photonic force microscopy — •Felix Jünger and Alexander Rohrbach — Department of Microsystems Engineering, Laboratory for Bio- and Nano-Photonics, University of Freiburg, Georges-Koehler-Allee 102, 79110 Freiburg, Germany

A particle diffusing in the vicinity of a living cell exerts broadband mechanical stimuli onto the cell membrane and influences the molecular processes of the cellular response. In this study, we demonstrate that molecular stimuli and the following cellular reorganization occur on different time scales.

We use photonic force microscopy (PFM) to approach optically trapped microbeads to the membrane of different biological cells and to track the bead’s temporal fluctuations with nanometer precision and on a broad spectral bandwidth up to 2 MHz. The autocorrelation of the bead motion reveals the friction coefficient γ(d), which changes significantly with the bead-membrane distance d. In addition, the frequency-resolved viscoelastic modulus G(ω,d) is obtained by analyzing the fluctuation data via the Kramers-Kronig relations.

Our results show that fluctuations of the incoming particle are slowed down and momentum transfer onto the cell is increased. Furthermore, we found evidence of a viscoelastic interaction of the bead with the cell coat, which is unique to HT29 cells and additionally regulates the momentum transfer to the cell surface and its mechanosensitive receptors.