Posted: May 23, 2007

Max Planck licenses technology providing unlimited resolution in microscopy

(Nanowerk News) Max Planck Innovation GmbH, the technology transfer agency of the Max Planck Society, Germany’s leading basic research organization, has signed a co-exclusive license agreement with Leica Microsystems and Carl Zeiss MicroImaging GmbH for the RESOLFT (reversible saturable optical fluorescent transitions) technology, a method providing molecular scale resolution with visible light and regular lenses for use in microscopy.
The technology is breaking the century-old diffraction resolution barrier in conventional microscopy and allows for resolution of the size order of a dye molecule, i.e. a sharpness of one or two nanometers. While a number of technologies such as electron microscopy exist to visualize virus particles, subcellular structures and macromolecules, RESOLFT fluorescence microscopy for the first time enables researchers to observe these structures inside of living cells without destroying them.
Both licensees will now seek to develop novel microscopes and imaging technologies based on the RESOLFT technology. "We decided to offer the technology for co-exclusive licensing to strengthen the German industry base," said Jörn Erselius, Managing Director of Max Planck Innovation. "However we decided to limit the number of co-licensing opportunities to three, so a third licence is still available. In addition the technology is still available for licensing in the field of creating a permanent structure with high three-dimensional resolution."
"The Carl Zeiss MicroImaging GmbH has in the past continuously screened for methods, which can be used for a better understanding of biological processes on a molecular scale," said Dr. Ulrich Simon, President and CEO of Carl Zeiss MicroImaging GmbH. "Unlike other methods that quench the excited fluorescence state to increase the optical resolution, RESOLFT involves considerably lower powers to be imposed on the sample. This opens great potential to advance the acquisition speed by parallelization of sample measurements. Carl Zeiss MicroImaging GmbH believes that these characteristics will make the RESOLFT method compatible with live cell imaging applications and an indispensable tool in modern microscopic imaging."
"We are excited about the potential of RESOLFT as an important tool for biological research," stated Dr. Martin Haase, General Manager of Leica Microsystems’ Life Science Research Division. "Our collaboration with Prof. Hell and his team at the Max Planck Institute for Biophysical Chemistry has recently led to the development of the awarded high resolution STED microscopy which will soon be available for our customers as a commercial product. We are confident that the RESOLFT method will open new avenues for research experiments leading to groundbreaking new results in a similar way as STED."


Ever since the light microscope was invented in the 17th century, its resolution (i.e. the ability to discriminate between two adjacent small objects) has been physically limited. In 1873, Ernst Abbe recognized that the optical separation of two objects is limited by the diffraction of light, and concluded that the resolution of a light microscope cannot be more accurate than half of the wavelength of light entering the microscope (Abbe’s Law). As a result, physicists believed that it is impossible for a light microscope to resolve details that lie closer together than 200 nanometers, barring the observation of viruses, macromolecules and many other subcellular structures with the human eye.
However, a team of researchers at the Max Planck Institute for Biophysical Chemistry in Göttingen led by Prof Dr Stefan Hell invented a method to overcome this barrier. The trick is done by using fluorescence marker molecules and two different light sources.
Fluorescence markers can be excited by light to send out fluorescent light, but light also can be used to extinguish ("quench") the fluorescence. In RESOLFT (reversible saturable optical fluorescent transitions) microscopy this principle is applied by illuminating a spot and subsequently quenching the fluorescence sent out by this spot in a way that the fluorescing area is reduced. This can be accomplished by over-saturating the quenching intensity.
As an example, the principle is applied in STED (Stimulated Emission Depletion) microscopy: A spot exciting fluorescence markers in a probe is superimposed by a doughnut-shaped quenching beam. As a result, the fluorescence is quenched everywhere in the focal spot except in the doughnut hole. By increasing the intensity of the doughnut-shaped beam, the fluorescent spot can be progressively narrowed down, in theory, even to the size of a molecule. For imaging, a probe is scanned by the ultra-sharp spot and the fluorescence intensities are then assembled by software.
Source: Max Planck Innovation GmbH