Berlin 2005 – scientific programme

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AKB: Biologische Physik

AKB 100: Poster Session I

AKB 100.35: Poster

Saturday, March 5, 2005, 16:45–18:45, Poster TU D

Optical tweezers for force measurements during voltage-driven DNA-translocation through a nanopore — •U. F. Keyser, B. Koeleman, D. Krapf, R. Smeets, N. H. Dekker, and C. Dekker — Kavli Institute of Nanoscience, Delft University of Technology, The Netherlands

We aim to measure in situ the forces acting on a DNA molecule that is traversing through a nanopore. We recently developed a technique for the controlled fabrication of nanometer sizes holes in silicon oxide or nitride membranes. We have shown that DNA molecules are pulled through such a nanopore by applying a voltage.

We have built optical tweezers with reflected light position detection that allow us to directly measure the forces and ionic current during the translocation process. The reflected light from the bead is used to monitor its position in three dimensions. A custom-made flow cell with optical access allows mounting nanopores in the optical tweezers and measure ionic currents.

We show simultaneous current and force measurements where polystyrene and silica beads in the optical trap are used to block pores with various sizes. We will report on currently on-going experiments where we probe the force on a bead that is attached to a long DNA molecule inserted in the nanopore.