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Proceedings Paper

Nanocapillaries and optical tweezers for studies on DNA in confinement
Author(s): Oliver Otto; Lorenz J. Steinbock; Ulrich F. Keyser
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Paper Abstract

We present measurements on single and multiple DNA molecules inside a nanocapillary. Nanocapillaries are single molecule sensors with similar properties as standard solid-state nanopores made from silicon nitride. For stalling of DNA in the nanocapillaries, we apply optical fiber illumination in combination with video detection for real-time tracking of optically trapped colloids on a microsecond time scale. Using a cross-correlation based algorithm after image acquisition from a CMOS camera we are able to measure the position of a colloid at rates up to 40,000 frames per second over hours. A full understanding of electrokinetic transport of polyelectrolytes in strongly confined environments is still elusive. In order to shed new light on this process we perform electrophoretic force and ionic-current measurements on single and multiple DNA molecules inside nanocapillaries attached to an optically trapped colloid. The hydrodynamic interaction between single DNA molecules was investigated by capturing multiple strands inside the tip of a capillary. We find that the capture force depends linearly on the number of DNA molecules.

Paper Details

Date Published: 9 September 2011
PDF: 9 pages
Proc. SPIE 8097, Optical Trapping and Optical Micromanipulation VIII, 80970B (9 September 2011); doi: 10.1117/12.894703
Show Author Affiliations
Oliver Otto, Univ. of Cambridge (United Kingdom)
Lorenz J. Steinbock, Univ. of Cambridge (United Kingdom)
Ulrich F. Keyser, Univ. of Cambridge (United Kingdom)


Published in SPIE Proceedings Vol. 8097:
Optical Trapping and Optical Micromanipulation VIII
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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