Back in the late 1800s, microscopist Ernst Abbe postulated that traditional light microscopy could never achieve a higher resolution than half the wavelength of light. This presumed physical limit, known as the Abbe limit, meant that for many years, scientists believed that resolution would never be better than 0.2 micrometers. But thanks to this year’s Nobel Laureates in Chemistry, we have surpassed this limit and can now peer into the nanoworld. By exploiting fluorescent molecules, these scientists have allowed us to visualize the movement of single molecules inside living cells, providing us with details of cellular processes on an unprecedented scale.
The winners are two US citizens, Eric Betzig from the Howard Hughes Medical Institute and William Moerner from Stanford University, and German citizen Stefan Hell from the Max Planck Institute. The prize was awarded “for the development of super-resolved fluorescence microscopy.”
Back in 2000, Hell developed a technique called “stimulated emission depletion microscopy.” His method involves using two different lasers; one stimulates the fluorescent dyes, whereas the other cancels out any fluorescence that is not in a nanometer-sized volume.
“I was wondering if there was still something profound that could be made with light microscopy, so I saw that the diffraction barrier was the only important problem that had been left over,” said Hell. “Eventually I realized there must be a way by playing with the molecules, trying to turn the molecules on and off allows you to see adjacent things you couldn’t see before.”
The other two scientists worked together but separately from Hell, pioneering a different method known as “single-molecule microscopy.” This involves taking multiple images of the same area, only exciting certain molecules each time, and then superimposing the images.
These techniques, which are known as “nanoscopy,” have allowed researchers to observe the activity of individual molecules in living cells in real-time, such as neurotransmitters whizzing around nerve terminals and proteins migrating in fertilized eggs as they divide to form embryos.
“On my level, the most impressive thing is to look at small molecules, to look at viruses in an atomic-resolved fashion,” Professor Thomas Barton, president of the American Chemical Society told BBC News. “It’s incredible what you can do now. On my timescale, if you had suggested being able to look at something on a one nanometer scale—an atomic scale—50 years ago, you’d have been laughed out of the room.”