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February 2010 Volume 5 No 2

Single-molecule fluorescence spectroscopy has allowed many chemical and biological systems to be studied both in vitro and in vivo. However, it is difficult to perform such measurements at temperatures above 37°C because the index-matching fluids used to direct light from the sample to the lens can also conduct heat, and this heating can damage the lens. Now Jerrod Schwartz, Stavros Stavrakis and Stephen Quake have shown that a colloidal titanium dioxide particle can act as a microlens when placed next to an emitting molecule. This microlens focuses light from the molecule into a conventional lens that is separated from the sample by air, which allows single-molecule measurements to be performed on biological systems in real time at temperatures as high as 70°C. This image is based on a simulation showing how light from a point source is focused by the microlens.

Cover design by Karen Moore

Letter p127; News & Views p99

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