Modern-day optical microscopists are breaking through the diffraction barrier, the long-held rule—imposed by the very nature of light waves—that limits how closely the cell’s inner workings can be scrutinized. Using clever tricks to sidestep the boundaries set by light’s innate tendency to spread, these scientists are zooming in to view the interior of organelles previously accessible only using labor-intensive electron microscopy. “It opens a new world,” says Stefan Hell, director of the Max Planck Institute for Biophysical Chemistry in Göttingen, Germany.
Conventional fluorescence microscopy cannot resolve a region smaller than some 200 nanometers across. That means that two objects closer than 200 nm will appear to be merged together. A single fluorescent macromolecule will also appear as a spread-out blur, so a 4-nanometer green fluorescent protein (GFP) will look like a 400-nanometer-wide smear, says Jennifer Lippincott-Schwartz, chief of the organelle biology section at the National Institute of Child Health and ...
