STED Imaging Works With Quantum Dots | Chemical & Engineering News
Volume 93 Issue 22 | p. 27 | Concentrates
Issue Date: June 1, 2015

STED Imaging Works With Quantum Dots

Quantum dots survive more than 1,000 scan cycles, could be useful for time-lapse imaging
Department: Science & Technology
News Channels: Analytical SCENE, Materials SCENE, Nano SCENE
Keywords: superresolution, STED, fluorescence microscopy

Most classes of fluorescent labels have been successfully used in the superresolution microscopy method known as stimulated emission depletion, or STED. The glaring exception has been quantum dots. In STED, one laser beam excites fluorescence and a second laser beam turns off the fluorescence in all but a small defined region. Quantum dots haven’t worked because their broad excitation spectra overlap the emission band, making it hard to identify an appropriate wavelength for stimulated emission shutdown of the fluorescence. Stefan W. Hell of the German Cancer Research Center and the Max Planck Institute for Biophysical Chemistry and coworkers now report successful STED microscopy with commercially available red-emitting quantum dots (Nat. Commun. 2015, DOI: 10.1038/ncomms8127). The researchers excite ZnS-coated CdSe quantum dots with 628-nm light and shut down the fluorescence with 775-nm light. By repeating the process in different spots, they build up images with spatial resolution of about 100 nm. The quantum dots survive more than 1,000 scans, which suggests they would be suitable for time-lapse STED imaging, according to the researchers.

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Cellular fibers labeled with red-emitting quantum dots can be better resolved with STED imaging (left) than with confocal microscopy (right).
Credit: Nat. Commun.
STED (left) and confocal (right) images of cellular fibers labeled with red-emitting quantum dots.
 
Cellular fibers labeled with red-emitting quantum dots can be better resolved with STED imaging (left) than with confocal microscopy (right).
Credit: Nat. Commun.
 
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