Berlin 2012 – scientific programme

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BP: Fachverband Biologische Physik

BP 24: Posters: DNA/RNA and Related Enzymes

BP 24.12: Poster

Thursday, March 29, 2012, 17:30–19:30, Poster A

Video-based axial force analysis for 3D quantitative optical tweezers — •Sebastian Knust, Andy Sischka, Andre Spiering, and Dario Anselmetti — Experimental Biophysics and Applied Nanoscience, Faculty of Physics, Bielefeld Institute for Biophysics and NanoScience (BINAS), Bielefeld University, 33615 Bielefeld, Germany

We developed and included video-based axial force analysis into our previously described optical tweezers setup [1]. By measuring the radius of a trapped microbead we achieve an overall force resolution along the z-axis in the range of 0.2pN with a bandwidth of 120Hz, only limited by our CCD camera. With this video-based method we overcome the remaining weak interference effects in backscattered light based force analysis when operating a microsphere in the vicinity of an interface.

We tested our setup by investigating the controlled threading and translocation of individual lambda-DNA molecules with and without attached DNA-binding ligands through solid-state nanopores and comparing these results with previous measurements realized with photodiode intensity detection [2, 3].

[1] A. Sischka et. al., Rev. Sci. Instrum. 79, 063702 (2008)

[2] A. Sischka et. al., J. Phys.: Condens. Matter 22, 454121 (2010)

[3] A. Spiering et. al., Nano Lett. 11, 2978 (2011)