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Intracellular 3-D Interactive Nanomanipulator

A.J. Kulik, J. Lekki, M. Lekka, E. Bertseva, A.S.G. Singh, P. Thévenaz, S. Puttini, S. Jeney, W. Nowak, G. Dietler, M. Unser, L. Forró

Proceedings of the Eleventh Annual Linz Winter Workshop, Advances in Single-Molecule Research for Biology & Nanoscience (ALWW'09), Linz, Republic of Austria, February 6-9, 2008, pp. 14.



A weak and very stable optical trap with detection of its 3-D position is called a Photonic Force Microscope. A small, few hundreds nm in diameter, polystyrene bead is trapped in the focal point of the laser. The position of the bead is digitized with high spatial (1 nm) and high temporal (1 us) resolution. The acquired signals allow us to follow the Brownian motion of the trapped bead, while the position of the focal point can be interactively changed relative to the sample, either directly (by executing precise table movements) or by the use of a force-feedback (haptic) joystick. The use of an IR laser (1064 nm wavelength) minimizes water absorption and allows us to work inside a living cell. Sufficient, for PFM measurements, in vitro uptake of polystyrene microspheres by human bladder cells (lines: HCV29 and T24) has been obtained after 24 hours. The motion of the intracellular beads is strongly influenced by the environment inside the cell, in particular, by the cell cytoskeleton, as compared to fluctuations of free beads in water.

A real-time 3-D stiffness matrix has been extracted from the XYZ high-frequency motions of the trapped beads using an analog hardware processor and a good agreement between classical, slow off-line analysis and the proposed real-time method was obtained.

A comparison between stiffness measurements of two cell lines, from outside using AFM and from inside using our system, will be presented.


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        Singh, A.S.G. and Th{\'{e}}venaz, P. and Puttini, S. and Jeney, S.
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