Berlin 2012 – scientific programme

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BP: Fachverband Biologische Physik

BP 17: Posters: Physics of Cells

BP 17.15: Poster

Wednesday, March 28, 2012, 17:30–19:30, Poster A

Non-Equilibrium Cell Mechanics Studied with Optical Traps — •Florian Schlosser, Florian Rehfeldt, and Christoph F. Schmidt — Drittes Physikalisches Institut, Georg-August-Universität Göttingen

Tissue cells communicate with their surroundings biochemically, but at the same time also sense the mechanics of their micro-environment. Cells can "feel" mechanical stress by generating contractile forces through their acto-myosin cytoskeleton and use these forces to actively probe the mechanical response of their extra-cellular matrix.

With a dual optical trap setup we have performed force measurements on cells suspended between two fibronectin-coated beads to ensure focal-contacts. We analyzed the correlated fluctuations of the beads with high spatial and temporal resolution by laser interferometry. Using a combination of active probing and passive recording of fluctuations (microrheology), we can simultaneously determine the (non-thermal) forces generated by the cells and quantitate their visco-elastic response properties.

The amount of contractile force transmitted to the outside varied with the trap stiffness. To elucidate the contributions of different mechanical elements to active and passive mechanical properties of the cell we employ biochemical perturbations and fluorescence microscopy allows us to visualize the distribution of cytoskeletal proteins in the cell.