Three scientists were awarded the 2014 Nobel Prize in Chemistry for their contributions to developing super-resolved fluorescence microscopy, which allows biologists to study cells on a nanometer scale.
Three scientists from the United States and Germany were awarded the 2014 Nobel Prize in Chemistry for their contributions to developing super-resolved fluorescence microscopy, a giant step forward in biomedical imaging that has given biologists a window into the inner workings of cells on a nanometer scale.
For most of the 20th century, scientists believed that it was not possible to resolve images smaller than half the wavelength of light (approximately 0.2 μm), a principle known as Abbe's diffraction limit. Nobel Laureates Eric Betzig, PhD, of Howard Hughes Medical Institute in Ashburn, VA; Stefan Hell, PhD, of the Max Planck Institute for Biophysical Chemistry in Göttingen, Germany; and William E. Moerner, PhD, of Stanford University in Palo Alto, CA, circumvented that principle by using fluorescence to map the position of molecules within a cell.
“Because of the methods they developed, we can now use a microscope with 10 times more resolution than what we had in the past,” says Carlos J. Bustamante, PhD, professor of chemistry, physics, and molecular and cellular biology at the University of California, Berkeley. “Scientists can now visualize how things are organized and function within cells, which has had, and continues to have, a profound impact on all of biological research.”
The award recognizes two revolutionary approaches that underlie what has become known as “nanoscopy”: stimulated emission depletion (STED) microscopy and Photo-Activatable Light Microscopy (PALM).
In the STED microscope, developed by Hell, one light pulse excites all the fluorescent molecules while another deactivates fluorescence almost everywhere except in a nanometer-sized volume in the middle. By sweeping along a cell sample and continuously measuring light in those small volumes, researchers can create a complete image of a cell at a much higher resolution than with a regular optical microscope.
Moerner was the first to measure fluorescence in a single molecule. He discovered that one variant of green fluorescent protein could be turned on and off at will by varying the wavelength of light, enabling scientists to isolate specific molecules within a cell.
Building on Moerner's work, Betzig developed PALM, a technique that uses weak light pulses to activate small subgroups of fluorescent proteins at different times, with a new subgroup activated each time the fluorescence dies out. The positions of the glowing proteins can be registered with a regular microscope because they are almost always more than 0.2 μm apart. The process produces multiple images that are then superimposed to create one extremely high-resolution image.
“By finding a way to determine where all the molecules are located in a sample, they solved the problem of how to distinguish between individual molecules that are closer together than the wavelength of light,” says Bustamante. “They separated in time what could not be separated in space.”
The Laureates will share the $1.1 million prize, which will be awarded on December 10 in Stockholm, Sweden.
For more news on cancer research, visit Cancer Discovery online at http://CDnews.aacrjournals.org.