STED microscopy: Breakthrough with a donut
Source: Leica Microsystems
STED microscopy (Stimulated Emission Depletion) is based on the fundamental principles of laser technology and fluorescence microscopy. Here, reducing the (fluorescent) focus is the key to increasing the optical resolution. With fluorescence microscopy, a focused laser beam excites dye molecules contained in a test sample so that they emit light. The afterglow of the dye stuff is used to improve the resolution. With STED technology, a second laser beam hits the sample directly after it has been excited by the first. This allows for the excited dye molecules to come to rest once again before the fluorescent light is emitted. The second beam is placed around the first one in the shape of a ring – like a donut – to ensure that only a few molecules glow in the center of the laser spot.
This method allows for structures inside the focal point to be displayed much more sharply, in a more structured manner and even spatially. In laboratory constructions, resolutions of 10 nanometers were even possible. “The limits of STED have yet to be reached,” assures Prof. Stefan Hell. The Director at the Max Planck Institute for Biophysical Chemistry in Göttingen has received numerous awards for his development that allows for molecular structures to be observed and thus the dreams of cell biologists to come true. <|