Tiny nano machines called macromolecular complexes participate in the most fundamental biological processes. The high-resolution three-dimensional (3D) structure of these complexes and their dynamic behavior can be studied by cryo electron microscopy. The molecular movies that can be obtained for these nano machines contribute tremendously to our understanding of molecular processes at a structural level.
Light microscopy has continually played a key role in science, but diffraction has limited the imaging of details that are smaller than about half the wavelength of light. For the important contrast mode of fluorescence, which is crucial to modern cell and molecular biology, the diffraction barrier has now been broken. In spite of relying on focused visible light, stimulated emission depletion (STED) microscopy is not limited by diffraction. To date, current schemes of STED-microscopy have delivered 50 nm (1/12 of the wavelength) resolution on cell membranes.