title: STED nanoscopy with fluorescent quantum dots.
abstract: The widely popular class of quantum-dot molecular labels could so far not be utilized as standard fluorescent probes in STED (stimulated emission depletion) nanoscopy. This is because broad quantum-dot excitation spectra extend deeply into the spectral bands used for STED, thus compromising the transient fluorescence silencing required for attaining super-resolution. Here we report the discovery that STED nanoscopy of several red-emitting commercially available quantum dots is in fact successfully realized by the increasingly popular 775 nm STED laser light. A resolution of presently ∼ 50 nm is demonstrated for single quantum dots, and sub-diffraction resolution is further shown for imaging of quantum-dot-labelled vimentin filaments in fibroblasts. The high quantum-dot photostability enables repeated STED recordings with >1,000 frames. In addition, we have evidence that the tendency of quantum-dot labels to blink is largely suppressed by combined action of excitation and STED beams. Quantum-dot STED significantly expands the realm of application of STED nanoscopy, and, given the high stability of these probes, holds promise for extended time-lapse imaging.
authors.affiliation: German Cancer Research Center (DKFZ), Optical Nanoscopy Division, Im Neuenheimer Feld 280, Heidelberg 69120, Germany.
authors.forename: Janina
authors.initials: J
authors.lastname: Hanne
authors.affiliation: German Cancer Research Center (DKFZ), Optical Nanoscopy Division, Im Neuenheimer Feld 280, Heidelberg 69120, Germany.
authors.forename: Henning J
authors.identifier: 0000000331591416
authors.initials: HJ
authors.lastname: Falk
authors.affiliation: German Cancer Research Center (DKFZ), Optical Nanoscopy Division, Im Neuenheimer Feld 280, Heidelberg 69120, Germany.
authors.forename: Frederik
authors.initials: F
authors.lastname: Görlitz
authors.affiliation: German Cancer Research Center (DKFZ), Optical Nanoscopy Division, Im Neuenheimer Feld 280, Heidelberg 69120, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Hoyer
authors.affiliation: German Cancer Research Center (DKFZ), Optical Nanoscopy Division, Im Neuenheimer Feld 280, Heidelberg 69120, Germany.
authors.forename: Johann
authors.initials: J
authors.lastname: Engelhardt
authors.affiliation: Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany.
authors.forename: Steffen J
authors.initials: SJ
authors.lastname: Sahl
authors.affiliation: 1] German Cancer Research Center (DKFZ), Optical Nanoscopy Division, Im Neuenheimer Feld 280, Heidelberg 69120, Germany [2] Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany.
authors.forename: Stefan W
authors.initials: SW
authors.lastname: Hell