Regensburg 2019 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 1: Protein structure and dynamics

BP 1.5: Vortrag

Montag, 1. April 2019, 10:45–11:00, H4

Compression of Single DNA Molecules in a Thermophoretic Trap — •Tobias Thalheim and Frank Cichos — Peter Debye Institute for Soft Matter Physics, Leipzig University, 04103 Leipzig, Germany

The Brownian motion of single DNA molecules, which are suspended in liquid, can be counter-acted by inhomogeneous temperature gradients which are generated by an optically heated metal structure of a thermophoretic trap. The trap [1] relying on thermophoresis, also known as Soret effect, consists of a focused laser beam which rotates on the ring-like metal nano-structure in a continuous fashion thereby generating the inhomogeneous temperature profile which, in turn, induces thermophoretic drift velocities preventing the free fluctuations of the DNA strand. Drift velocities in outer regions of the trap are due to the inhomogeneity of the temperature landscape larger than those closer to the trapping center. An elongated soft molecule like DNA therefore experiences different drift velocities at different parts of the molecule in the trap leading to a compression of the DNA strand which is reflected in a decreased radius of gyration. The influence of the trap on the conformation dynamics of the DNA molecule will be studied with a model-free statistical tool which is called principal-components analysis applied as introduced by Cohen and Moerner [2].

References

[1] M. Braun, A. P. Bregulla, K. Günther, M. Mertig, and F. Cichos,

Nano Lett 15, 5499--5505 (2015)

[2] A. E. Cohen, and W. E. Moerner, PNAS 104, 12622--12627 (2007)