The world’s fastest nanoscopy method
Researchers led by Stefan Hell at the German Cancer Research Center (DKFZ) have tremendously increased the imaging speed of high-resolution optical STED nanoscopy. Their results, which they have now published in “Nature Methods”, show that imaging of up to 1,000 frames per second is possible. This facilitates taking high-resolution videos at millisecond temporal resolution, for example, of transport processes in living neurons or of viruses exploring the surface of a cell before entering it, the researchers reported in first application examples.
© Jale Schneider und Jasmin Zahn, Abteilung Optische Nanoskopie, Deutsches Krebsforschungszentrum
Light microscopy is one of the most important methods in modern biomedical research. Researchers use fluorescence to selectively label and then directly observe biomolecules, even in living cells and tissues. In recent years, the spectrum of possibilities of this technique has expanded rapidly, since new approaches have made it possible to overcome the so-called “diffraction limit” of resolution in conventional optical microscopy. Light can now also be used to obtain images of objects at nanometer scale, i.e., at a resolution that is getting increasingly close to that of electron microscopy.
After the 2014 Nobel Prize in Chemistry “for the development of super-resolved fluorescence microscopy” had honored Stefan.Hell as the pioneer of this development (Hell shares the prize with his American colleagues Eric Betzig and William E. Moerner), he next wanted to take temporal resolution – following spatial resolution – to the limits of what is possible.
High temporal resolution is important whenever processes happen at such speed that a whole series of images is necessary in order to be able to recognize the details of what is happening. If obtaining a single image takes too long, the movement gets blurred, just as it does when one takes a photograph of a fast moving car with a long exposure time. Ideally, one obtains a high number of images in direct sequence as rapidly as possible.
During her PhD thesis in Hell’s group, Jale Schneider, supervised by Johann Engelhardt, developed a novel, technically sophisticated technique by which the laser beams in the STED method can scan the sample at a previously unknown rate: In the experiments described, the laser focus moves 4,000 times faster than before. The ultrafast image build-up turns this STED approach into the fastest nanoscopy method that currently exists worldwide.
Using this method, the researchers were able to obtain high-resolution images of rapidly progressing dynamic processes such as vesicle motions in neurons of fly larvae (see picture) and of AIDS viral particles prior to and during cellular uptake. These application examples are based on many years of intensive collaboration of Hell’s Heidelberg working group with the laboratories of Hans-Georg Kräusslich (Heidelberg University Hospital) and Stephan Sigrist (Freie Universität Berlin).
Further development of STED and related technologies and their application in medical research is the main goal of the Division of Optical Nanoscopy at the DKFZ in Heidelberg. Stefan Hell also is a director of the Max-Planck Institute for Biophysical Chemistry in Göttingen.
J. Schneider, J. Zahn, M. Maglione, S.J. Sigrist, J. Marquard, J. Chojnacki, H.-G. Kräusslich, S.J. Sahl, J. Engelhardt, S.W. Hell: Ultrafast, temporally stochastic STED nanoscopy of millisecond dynamics. Nature Methods 2015, 10.1038/nmeth.3481
With more than 3,000 employees, the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) is Germany’s largest biomedical research institute. DKFZ scientists identify cancer risk factors, investigate how cancer progresses and develop new cancer prevention strategies. They are also developing new methods to diagnose tumors more precisely and treat cancer patients more successfully. The DKFZ's Cancer Information Service (KID) provides patients, interested citizens and experts with individual answers to questions relating to cancer.
To transfer promising approaches from cancer research to the clinic and thus improve the prognosis of cancer patients, the DKFZ cooperates with excellent research institutions and university hospitals throughout Germany:
The DKFZ is 90 percent financed by the Federal Ministry of Education and Research and 10 percent by the state of Baden-Württemberg. The DKFZ is a member of the Helmholtz Association of German Research Centers.
