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BP: Fachverband Biologische Physik
BP 26: Posters II
BP 26.31: Poster
Donnerstag, 28. Februar 2008, 17:00–19:30, Poster A
Coated particles as enhanced probes for optical tweezers — •Anita Jannasch1, Volker Bormuth1, Jonathon Howard1, and Erik Schäffer2 — 1MPI of Molecular Cell Biology and Genetics Dresden — 2BIOTEC Dresden
In an optical trap, micron-sized dielectric particles in aqueous solutions can be held by a tightly focused laser beam. The optical force on the particle is composed of an attractive gradient force in the direction of highest light intensity, and a scattering force in the light propagation direction, that pushes the particle away from the focus and thereby weakens the trap. To optimize the trapping potential, we reduce the scattering force by using coated microspheres. The shell of the particle is designed such that it acts as an anti-reflection coating. We characterized such particles and found in comparison with the same-sized uniform microspheres a more than two-fold strengthening of the trap. By improving the trapping potential higher overall forces can be achieved with the same laser power, or vice versa the same force can be reached by using less laser power. A higher maximal force increases the range of possible experiments, and a reduced laser intensity leads to less photo-toxic interactions relevant for biological applications, like in vivo cell measurements.