Dresden 2017 – scientific programme

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BP: Fachverband Biologische Physik

BP 24: Posters - Protein Structure and Dynamics

BP 24.7: Poster

Tuesday, March 21, 2017, 14:00–16:00, P1A

Thermophoretic trapping of single molecules — Tobias Thalheim, Marco Braun, Andreas Bregulla, and •Frank Cichos — Molecular Nanophotonics Group, Institute of Experimental Physics I, University of Leipzig, Germany

We present a force-free trapping method with is capable of confining the Brownian motion of single molecules by applying the actual fuel of Brownian motion: temperature. A focused laser beam is used to optically heat a plasmonic structure generating dynamical temperature gradients. Single molecules migrate in these temperature gradients typically to colder regions due to an effect known as thermophoresis or Ludwig-Soret effect. An optical feedback algorithm utilizes this behavior to reposition the focused laser beam and, hence, restricts the Brownian motion of the single molecule. As a first biological model system, double-stranded lambda-DNA is investigated in the thermophoretic trap. The macromolecular conformational changes due to the inhomogeneous temperature gradients are evaluated with the help of a principal component analysis. Furthermore, the Soret coefficient of single 6-helix bundle DNA origami structures has been measured in the trap.