Issue Date: January 4, 2010
Colloidal Lenses Turn Up The Heat
Some biological systems are too hot for single-molecule-imaging studies: At temperatures higher than 50 °C, heat conduction from the sample to the immersion objective through a refractive-index-matching oil can cause the high-numerical-aperture lens to fail. Stephen R. Quake, Jerrod J. Schwartz, and Stavros Stavrakis of Stanford University now show that spherical colloidal particles can be used in combination with low-numerical-aperture air objectives as lenses for high-temperature single-molecule imaging (Nat. Nanotechnol., DOI: 10.1038/nnano.2009.452). Quake and colleagues attached 2-μm TiO2 colloids to a glass surface via fluorescently labeled molecules. The colloids act as lenses for the molecules they are attached to. This setup allows the researchers to heat samples without also heating the lens. They used the method to study individual thermophilic DNA polymerase enzymes operating at temperatures as high as 70 °C. Such colloidal lenses could make it possible to use high-temperature polymerase enzymes in single-molecule DNA sequencing-by-synthesis technologies, the researchers suggest.
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