Max Planck Inst. for Biophysical Chemistry
By Richard Van Noorden
Ever since the seventeenth century, when the early microbiologist Antonie van Leeuwenhoek focused light through lenses and marvelled at the cells that swam before his eyes, microscopes have opened up new vistas of discovery. This year, the Nobel Prize in Chemistry went to three scientists who defied the limits of light microscopes to reveal sharp images of molecular-scale structures in living cells.
The advances made by Stefan Hell, William Moerner and Eric Betzig in the 1990s and 2000s mean that biologists can now see, in real time, how proteins are distributed and move inside cells — at the junctions between neurons, for example, or in fertilized eggs dividing into embryos.
“It is really a revolution for the life sciences, because we can see structures that we could never see before,” says Stefan Jakobs, who works with super-resolution techniques at the Max Planck Institute for Biophysical Chemistry in Göttingen. Or as the Nobel committee put it: “Microscopy has become nanoscopy.”
No matter how clean their lenses, optical microscopes inevitably provide a blurry view of the molecules inside cells, as German physicist Ernst Abbe realized in 1873. The laws of physics dictate that visible light cannot distinguish between objects closer to each other than around 200 nanometres (around half the wavelength of visible light) — they will appear as one blob. Such resolution, known as Abbe’s diffraction limit, is good enough to reveal the organelles inside cells but not to see their detailed structures. Microscopes that use beams of electrons, rather than light, have finer resolution, but they can be used only in a vacuum, limiting their use to dead tissue.
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