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2014 Nobel prizes for Chemistry: Resolve to do better

By FnF Desk | PUBLISHED: 10, Oct 2014, 19:28 pm IST | UPDATED: 10, Oct 2014, 19:28 pm IST

2014 Nobel prizes for Chemistry: Resolve to do better In 1674 Antonie van Leeuwenhoek, a Dutch draper with a penchant for optics, discovered a new world. Peering through his pioneering home-made microscopes at a drop of pond water, he found it alive with tiny creatures swimming to and fro. That life could exist on such tiny scales was completely unexpected. His observations marked the first time anyone had seen what are in modern times known as bacteria, algae and the like.
 
Microscopes have come a long way since van Leeuwenhoek's time. But there is a fundamental limit to how good they can be. In 1873 a German physicist named Ernst Abbe proved that a microscope could not discern features smaller than about half the wavelength of the light used by the microscope. A high-quality visible-light microscope, then, would be capable of seeing some of the tiny structures within a living cell. But anything smaller—viruses, proteins and so on—would remain forever out of reach.
 
Or so it was thought. On October 8th, Sweden's Royal Academy of Science awarded the Nobel prize in chemistry to three scientists: Eric Betzig, Stefan Hell and William Moerner, for their work in inventing a creative way to circumvent Abbe's resolution limit.
 
Dr Hell, of the Max Planck Institute for Biophysical Chemistry, in Germany, relied on lasers to pull off the trick. By delivering precisely calibrated pulses of energy, lasers can be used to make certain molecules glow temporarily in a process called fluorescence. Such fluorescence can be quelled by light of another colour.

Dr Hell's system uses two combined beams, one designed to induce fluorescence and another designed to suppress it over the same area—but for a tiny part in the centre. By sweeping the paired beam across a sample and measuring the light emitted by the few remaining central molecules, features much smaller than the Abbe limit can be resolved.
 
Dr Betzig, of Howard Hughes Medical Institute, in Maryland, and Dr Moerner, of Stanford University, in California, also relied on fluorescence. In their techique, a biological sample is tagged with a bespoke fluorescent protein.

A weak light of the correct wavelength is shone on the sample, which persuades some small fraction of the fluorescent molecules within it to light up. An image is taken, the light is switched off, and the procedure is repeated.

Each exposure triggers a different subset of the fluorescent molecules to glow. As the approach is repeated, every tagged molecule is lit up, and a picture is built up that neatly cheats Abbe's limit.
 
The chief advantage of both techniques is that they can be used to study cellular processes as they happen. A technique called electron microscopy can resolve far smaller details than can optical microscopy, but it must take place in a vacuum; it is suitable only for samples that are dead, or that were never alive.

The approaches pioneered by Drs Hell, Betzig and Moerner, by contrast, allow scientists to watch proteins being shuttled around a cell, or to see individual neurons create and prune connections to other neurons—in other words, to watch life as it unfolds. #Source: The Economist