Dresden 2014 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 41: Biomaterials and Biopolymers II (joint CPP/BP)
BP 41.8: Vortrag
Donnerstag, 3. April 2014, 17:15–17:30, ZEU 222
DNA Interactions in Crowded Nanopores — Nadanai Laohakunakorn1, Sandip Ghosal2, Oliver Otto1, Karolis Misiunas1, and •Ulrich F. Keyser1 — 1Cavendish Laboratory, University of Cambridge, JJ Thomson Ave, CB3 0HE Cambridge, UK — 2Northwestern University, Evanston, IL 60208-3109, USA
The motion of DNA in crowded environments is a common theme in physics and biology. Examples include gel electrophoresis and the self-interaction of DNA within cells and viral capsids. Here we study the interaction of multiple DNA molecules within a nanopore by tethering the DNA to a bead held in a laser optical trap to produce a *molecular tug-of-war*. We measure this tether force as a function of the number of DNA molecules in the pore and show that the force per molecule decreases with the number of molecules [1]. A simple scaling argument based on a mean field theory of the hydrodynamic interactions between multiple DNA strands explains our observations. At high salt concentrations, when the Debye length approaches the size of the counterions, the force per molecule becomes essentially independent of the number of molecules. We attribute this to a sharp decrease in electroosmotic flow which makes the hydrodynamic interactions ineffective.
[1] N. Laohakunakorn, S. Ghosal, O. Otto, K. Misiunas, and U. F. Keyser. DNA Interactions in Crowded Nanopores. Nano Letters, 13(6):2798-2802, (2013).