Fluorescent Microscopy

Nobel Prize in Chemistry Awarded to Chemists Who Developed Super-resolved Fluorescent Microscopy

Picture of three Chem guys.
Author: Madeleine Ielmini
Date: October 15, 2014

On October 8th, the Nobel Prize in Chemistry was jointly awarded to three chemists who developed super-resolved fluorescent microscopy. Dr. Eric Betzig of the Janelia Research Campus at Howard Hughes Medical Institute in Virginia, Dr. Stefan W. Hell of the Max Planck Institute for Biophysical Chemistry and German Cancer Research Center, and Dr. William E. Moerner of Stanford University were jointly awarded the prize for their groundbreaking work in the field of microscopy done in the early 2000s. Prior to the research of Drs. Betzig, Hell and Moerner, it was believed that the best resolution possible for a microscope was half the wavelength of light, which would prevent scientists from using light microscopy to study the minutest of details. The use of electron microscopy allowed for greater resolution because the wavelength is smaller than the wavelength of visible light. However, the use of electron microscopy on living cells presents many challenges. The work of Dr. Betzig, Hell and Moerner opened the door to a new world of research on the previously unobservable.

In the early 2000s, Dr. Hell created a Stimulated Emission Depletion (STED) microscope to test his theoretical calculations that resolution better than half the wavelength of light could be achieved. The STED used a low intensity laser beam and a high intensity, red-shifted STED beam that increased in intensity from the focal region. The low intensity beam and the STED beam, when pulsed at the correct intervals, functioned to turn off light emission in all but a small part of the diffraction limited focal region. As the maximum intensity of the STED beam is increased the resolution limit approaches zero.

While STED allows for an amazing improvement in the resolution of images, it can damage biological tissues. Further development led to what is known as Super-resolved Single Fluorophore Microscopy. This class of microscopy allows for a very high degree of resolution due to the ability to super-localize a point source of photons. The detection of the spread of photons from a single emission source allows for a much higher resolution that theorized by Abbe's limit.

In the late 1990s, while studying the light emission properties of green fluorescent protein (GFP), Moerner discovered that it was possible to cause proteins to fluoresce at different wavelengths using the inherent photochemistry of the proteins. This meant that different proteins could be caused to fluoresce temporarily or permanently by irradiating them with different wavelengths. Betzig later used this idea to activate GFP mutant fluorescence in different phases by using different wavelengths and obtaining a super-resolved image in what is referred to as Photoactivated Localization Microscopy.

The STED microscope and Single-flourophore based microscopy methods have allowed for major advances in research, especially in the areas of biological science. The development of STED and Single Fluorophore Microscopy has, and will continue to have, a massive impact on the study of the minute details of biological sciences, opening doors to novel types of research. It is no wonder that these brilliant men, who made such significant contributions to this impactful development, were awarded a Nobel Prize in Chemistry this year.

Bibliography

"The Nobel Prize in Chemistry 2014". Nobelprize.org. Nobel Media AB 2014. Web. 8 Oct 2014. http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2014/

"Scientific Background on the Nobel Prize in Chemistry 2014: Super- Resolved Fluorescence Microscopy." Royal Swedish Academy of Sciences. Web. 8 October 2014. http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2014/advanced-chemistryprize2014.pdf

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