Zeroing In on Single Molecules

See allHide authors and affiliations

Science  31 Jan 2003:
Vol. 299, Issue 5607, pp. 621
DOI: 10.1126/science.299.5607.621e

The use of conventional fluorescence to detect single molecules normally requires dilute conditions (nanomolar to picomolar conditions). Levene et al. (p. 682, see the cover and the Perspective by Laurence and Weiss) introduce an optical waveguiding method that decreases the observation volume and thus allows the micromolar concentrations more typical of biological conditions to be used. Their zero-mode waveguides consist of pinholes in a metal film over a glass slide that form the wells for the solution. No propagating electromagnetic modes exist in this configuration, so only molecules at the glass surface can adsorb radiation. The activity of immobilized DNA polymerase with fluorescently tagged nucleotides was followed with microsecond resolution.

Navigate This Article