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BP: Fachverband Biologische Physik

BP 12: Posters: New Technologies

BP 12.8: Poster

Montag, 14. März 2011, 17:15–20:00, P3

Using an ultrastable AFM to measure pN-forward forces of a growing neuronal Growth Cone — •Thomas Fuhs and Josef A. Käs — Universität Leipzig, Soft matter physics, Leipzig, Germany

We have already shown how to use an AFM to measure forward pushing protrusion forces of fast moving fish keratocytes on glass substrates at room temperature. But when trying this technique to measure slow moving neuronal growth cones at 37°C, one can no longer assume a drift-free system because of thermally induced artifacts. Therefore we incorporated an optical trap into our AFM-setup to measure, and correct for, the substrate's drift. Yet the scan head of the AFM does not allow using the forward scattered signal of the optical trap. To get position information nonetheless we use the backscattered light of our marker bead. With this we can still reduce the drift of the AFM scan head with respect to the substrate to less than 50 nm/h in all 3 dimensions. Using this stabilization we can realize the necessary observation times of 1h and even longer, while still being sensitive in the pN force range.