STED microscopy creates high-resolution images far below the diffraction limit of visible light. However, the technique’s engineering aspects remain comparatively complex, which impedes its dissemination and use. A technology called EASYDOnut, developed by the Max Planck Institute for Biophysical Chemistry and the German Cancer Research Center, simplifies the optical system considerably and has now been licensed by spin-off Abberior GmbH. EASYDOnut precisely guides the laser beams of the STED microscope onto the sample being investigated by means of a single optical element. This innovation can encourage the spread of STED microscopy and benefit medical research. STED microscopy permits significant information to be obtained, even from living human cells.
Living cells can be investigated with modern fluorescence microscopy. In this process, suitable molecules within the cells are tagged with fluorescent dyes, which are then excited with light so they fluoresce. However, using conventional microscopy, no adjacent details closer than 200 nm to one another can be distinguished (due to diffraction limiting and resolution limited by the Abbe number). The reason for this lies in the wave nature of light and the inherent spatial expansion of a beam’s focal point.
With STED microscopy, this focal point illuminating the fluorescing sample is made smaller by preventing the region surrounding the spot of light from fluorescing. This is accomplished by projecting a ring-shaped, second beam of light co-axially with the main beam, but at a different wavelength, one which suppresses fluorescence of the excited dye molecules at the edge of the main beam through what is known as stimulated emission.
Thanks to EASYDOnut, both beams of light can originate from a single point source, so there is no need for time-consuming alignment of the beams with one another. That saves users the cost of frequent technical maintenance. The big advantage of the EASYDOnut system lies in its very simple operation. “As a leading manufacturer of commercially available fluorescent dyes for new techniques in microscopy, the EASYDOnut system we offer our customers is a carefully tuned pairing of optical components and dyes for STED microscopy,” according to Gerald Donnert, Managing Director of Abberior GmbH.
The new technique was developed jointly with the inventor of STED microscopy, Prof. Stefan Hell from the MPI for Biophysical Chemistry, together with Johann Engelhardt and Matthias Reuss from the Optical Nanoscopy Department of the German Cancer Research Center (DKFZ) as well as Volker Westphal and Lars Kastrup from the MPI for Biophysical Chemistry. The invention has been patented and licensed by Max Planck Innovation and the DKFZ Office of Technology Transfer.
“The innovation simplifies the use of STED microscopes considerably. Observing biological processes in the micro-world of cells is simplified as well as improved, and thus it opens up new paths in biological research and medical diagnostics,” explains Bernd Ctortecka, Patent and Licensing Manager of Max Planck Innovation. EASYDOnut can be manufactured in an almost unlimited variety of optical wavelength combinations
Source: Max Planck Institute