Regensburg 2013 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 24: Posters: Physics of Cells

BP 24.6: Poster

Mittwoch, 13. März 2013, 17:30–19:30, Poster C

Cell visco-elasticity measured with AFM and optical trap at sub-micron deformations — •Paula Sánchez, Weixing Li, Marie Zeiss, Carina Wollnik, Kai Bodensiek, Florian Rehfeldt, and Iwan Schaap — III. Physikalisches Institut, Faculty of Physics, Georg-August Universität Göttingen, Germany

The elastic properties of cells are widely used as an indicator for differentiation, response to drug treatment, or the effects of the supporting matrix on cell development. We use vertical optical trapping and AFM to measure the cell's visco-elastic response at deformations of 0.2 to 1.2 um. To perform the optical trapping experiments at different speeds we implemented an FPGA based fast force feedback to control the vertical movement of the piezo at speeds up to 50 um/s. We use this combined approach to quantify the visco-elasticity at small and large deformations on both stiff and soft substrates. Deformations up to 0.2 um showed a reversible, thus truly elastic response that was independent of the rate of deformation. At higher indentations, the apparent Young's modulus increased a multifold due to viscous effects that followed a weak power law. Both AFM and optical trapping indentation experiments give consistent results for the cell elasticity. Optical trapping has the benefit of a lower force noise, which allows a more accurate determination of the absolute indentation.