Dresden 2009 – scientific programme

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BP: Fachverband Biologische Physik

BP 12: Single Molecules

BP 12.5: Talk

Wednesday, March 25, 2009, 11:00–11:15, HÜL 186

Dual-focus flow detection: Exposing biological heterogeneity one molecule at a time — •Tyler Arbour, Anastasia Loman, and Jörg Enderlein — III. Institut für Physik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen

The ability to distinguish between multiple fluorescent species or states in solution at the single-molecule level is an attractive concept. To realize this level of analysis in confocal detection, we must eliminate the uncertainty introduced by random diffusion of the molecule. In other words, we must know the path a molecule takes through the confocal detection volume. In a conventional detection scheme, this translates into directing the fluorescent species through the confocal volume's center using, for example, a microinjection sample capillary surrounded by a continuous sheath fluid flow. This has been successfully demonstrated in the past, first by Richard Keller et al in the sizing of individual dye-labeled DNA fragments.[1] However, such a setup is difficult to build, and the nanometer-scale components are very prone to clogging as well as unwanted fluorophore-capillary interactions; as a result, this idea has been largely abandoned. Here we present a much simpler setup that takes advantage of dual-focus detection in a net fluid flow to achieve precise knowledge of a molecule's path.

1. Goodwin, P.M., et al., Nucleic Acids Research, 1993. 21(4): p. 803-806