Nobelpreis für Stefan Hell

Verleihungszeremonie in Stockholm

Bildquelle: Bernd Schuller/MPI für biophysikalische Chemie

Am 10. Dezember verlieh Schwedens König Carl XVI. die Nobelpreise für Medizin, Physik und Chemie. Der deutsche Physiker Stefan Hell teilt sich den Preis für Chemie mit Eric Betzig und William E. Moerner. Die drei Wissenschaftler erhalten die Auszeichnung für die bahnbrechende Entwicklung eines neuartigen optischen Mikroskops, mit dem Forscher zehnmal kleinere Strukturen als bisher erkennen können

Researchers wishing to heal diseases have to take a very close look. The processes determining whether a person is healthy or not take place inside cells, that is, on a molecular level. Until recently, researchers were unable to investigate these processes in living cells because conventional light microscopes did not provide the necessary resolution. A maximal resolution of 0.0002 millimetres was considered the limit of microscopy. Objects grouped closer together could not be differentiated from each other. Microscope images were blurred and unfit for scientific purposes. The reason is a physical law that was considered irrefutable until recently: the diffraction limit of light waves as stipulated by physicist Ernst Abbe in 1873.

Das linke Bild wurde mit einem herkömmlichen Lichtmikroskop (konfokal) aufgenommen. Gezeigt werden Strukturen im Zellkern (gelb). Die Verteilung der einzelnen Strukturen sind im rechten Bild viel deutlicher sichtbar. Diese Aufnahme wurde mit einem STED-Mikroskop gemacht. Damit können in biologischen Strukturen, Auflösungen von unter 30 Nanometern erreicht werden. Bildquelle: Deutsches Krebsforschungszentrum, in Kooperation mit der Abteilung Molekulare Genetik - Prof. Dr. Peter Lichter

Stefan W. Hell, however, has come up with the crucial idea of bypassing the diffraction limit of light. This has earned him the Nobel Prize in Chemistry together with US American researchers Eric Betzig and William Moerner. With his STED microscope (Stimulated Emission Depletion), he developed a technology enabling researchers to investigate individual molecules in living cells at up to ten times the previously possible resolution. The process uses the characteristics of fluorescence dyes. The STED method employs two laser beams; the first laser beam stimulates fluorescent markers within the cells to glow, the second cancels out all fluorescence except for that in those molecules that are of interest to the researchers. The second laser beam returns all other molecules to their original state, switching their fluorescence off. This enabled Hell to minimise the focal spot, that is, to reduce the number of light points under the microscope so that the glare does not obscure everything else. This renders finest structures visible. The sophisticated method enables the observation of processes in living cells on a scale of 20 to 50 nanometres. "At the start", Stefan Hell looks back, "nobody wanted to believe in it. But now it is clear: the vision of optical nanoscopy has become a reality."

The STED microscopes developed by Hell are used worldwide for researching biological processes and contribute to the rapid progress in medical basic research. In his capacity as head of the Division Optical Nanoscopy at the German Cancer Research Center (DKFZ) in Heidelberg, Hell and his team work on further developing STED microscopy in medical basic research. The huge advantage of the method is that also living cells can be investigated on a nanometre scale. "It is a great feeling to see STED microscopy giving such a huge boost to medical basic research", says Hell.

10.12.2014 Martin, Trinkaus, Silvia Zerbe und Sebastian Grote

Verleihungszeremonie in Stockholm

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