Berlin 2024 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 8: Poster Session Ia

BP 8.34: Poster

Montag, 18. März 2024, 18:00–20:30, Poster C

Studying cell-particle-interactions using blinking holographic optical tweezers — •David Gitschier, Wolfgang Gross, Manuel Eisentraut, Konrad Berghoff, and Holger Kress — Department of Physics, University of Bayreuth, Bayreuth, Germany

The corona pandemic underlined the importance of a healthy immune system. An indispensable part thereof are the interactions with infected cells and bacteria as well as their subsequent uptake. However, a complete mechanical characterization of this dynamic process still lacks. Here we show how to measure mechanical properties of immune cells during interaction with particles using the versatile technique of blinking holographic optical tweezers. This method enables us to obtain the binding kinetics and viscoelastic parameters of the cellular response. The latter are consistent with power law rheology. Using this, we determine the temporal evolution of the contact radius between particle and cell leading to the timescale of the binding kinetics. Regarding the material softness, addition of cytochalasin D resulted in an increase of the cellular compliance and fluidization of the cortex. Moreover, we visualize the influence of the cortical actin structure by fluorescence microscopy with Lifeact-GFP-transfected cells. Therefore the actin dynamics after initial cell-particle-contact are accessible. Our approach helps elucidating the biomechanical processes underlying this important part of innate immunity. Additionally it allows us to address important, yet unanswered questions like how different microplastic particles interact with cells.

Keywords: cell-particle-interactions; optical tweezers; cell mechanics; phagocytosis; actin dynamics