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BP: Fachverband Biologische Physik

BP 12: Poster II

BP 12.21: Poster

Dienstag, 2. April 2019, 14:00–16:00, Poster B2

Nanomechanical sub-surface mapping of cells by atomic force microscopy — •Lukas Stühn, Anna Fritschen, and Christian Dietz — Physik der Oberflächen, Materialwissenschaften, TU-Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt

We aim to visualize nanomechanical properties of the cell's interior with the atomic force microscope. Compared to optical methods, the atomic force microscope can sense the mechanical properties of cells with high spatial and depth precision. In combination with fluorescence microscopy methods cell processes can be specifically investigated. We demonstrate how the atomic force microscope can be utilized to produce nanomechanical maps of human breast cancer epithelial cells.

To this end, we exploit conventional force-distance techniques or dynamic approaches where we force the cantilever to oscillate in several cantilever eigenmodes (flexural/torsional) simultaneously and record the cantilever motion as function of the tip-sample indentation at each pixel. Thus, tip-sample interactions in different spatial directions can be reconstructed and mapped in various sample depths.

We can mechanically distinguish several components of the cell's interior. The nucleus and cytoskeleton are clearly visible. Within the nucleus, nucleoli appear as mechanically stiffer, small round objects. In cross-sections drawn through the three-dimensional maps, the stiff cytoskeleton that mechanically stabilizes the cell becomes apparent in the proximity of the membrane. Strikingly, the soft gel-like cytosol within the cell can be detected beneath this stiff enclosure.