Körber Science Prize Awarded to STED Originator

Stefan Hell of Max Planck Institute for Biophysical Chemistry in Göttingen has been awarded the 2011 Körber European Science Prize for his pioneering discoveries in the field of optics.

Stimulated emission depletion, or STED, microscopy, which Hell invented and developed to application readiness, allows microscopists to gain insights into the nano world far beyond the Abbe limit. For example, neurophysiologists using the new resolution of only a few dozen nanometers provided by the technique succeeded in visualizing the movements of tiny synaptic components for the first time. In addition, the concept underlying STED microscopy opened up new prospects for the further development of optical storage media.

Hell overcame Abbe’s barrier in the imaging of fluorescent objects. In this process, which is used widely in biology and medical research, the specimens to be examined are marked with fluorescent molecules and illuminated, typically with a laser. The beam excites the molecules so that they emit fluorescent light, thereby making the marked cell components visible. Here, too, the fluorescent light emitted by the closely adjoining dots becomes an indistinct blur, but Hell found a simple trick to break through Abbe’s barrier. This ensures that the cell components illuminated by the excitation beam do not emit fluorescence simultaneously, but sequentially. To achieve this, Hell applies a second beam (STED beam), which temporarily prevents the fluorescent markers from emitting light – that is, it switches them off.

In his STED microscope, this second, ring-shaped "switch off" beam is superimposed with the ~200-nm circular focal area of the excitation beam, where it keeps all of the specimen’s features dark, except those at the very center of the ring. Only the molecules in this zone are registered. Scanning the two beams across the specimen also separates the cell components that are much closer together than 200 nm. The images are consequently yielded with fundamentally improved resolution.

Hell will receive €750,000 in prize money for his research project on new fluorescent dyes that can be switched on and off with much less light. This would further increase the attainable resolution. Moreover, potentially harmful effects of the light on the observed cells and tissue could be reduced, as the intensity of the laser radiation required would be lower.

Each year, the Körber Prize is awarded to an outstanding scientist working in Europe on particularly promising projects. The prizewinner is selected by an international trustee committee chaired by Peter Gruss, president of the Max Planck Society. The 2011 prize will be presented to Hell on Sept. 7, 2011, in the Great Festival Hall in Hamburg.

For more information, visit: www.koerber-prize.org