A super-high-resolution 3-D light microscope developed at the Max Planck Institute for Biophysical Chemistry will allow biologists to watch the workings of the tiniest organelles and even individual clusters of proteins in living cells at a resolution of 40 nanometers.

The Max Planck group developed a way to get around light’s fundamental wavelength limitations by using two beams instead of one. The first light beam plays the same role–and is the same spot size–as light in a conventional microscope. It moves through the cell under study, exciting fluorescently labeled molecules inside the cell to fluoresce. The second beam “sculpts” the first, says Hell, inhibiting fluorescence created by the edges of the first beam. That reduces the effective spot size to 40 to 45 nanometers in diameter.
Molecular-resolution microscopy is expected to improve patient care and play an important role in advancing personalized medicine in the future.