How many of you have used a magnifying glass - perhaps to examine a blade of grass or a bug you caught in your backyard?
The desire to learn about the microscopic world has inspired people through centuries to invent powerful instruments. They experimented with lenses and light sources, and discovered that they could enlarge objects.
In the 17th century, Anton van Leeuwenhoek invented the first real microscope that could magnify 270 times. It opened a whole new world of bacteria, yeast, and other micro-organisms, as well as allowed him to see inside blood vessels. Advances in light microscopes continued. But, we were starting to hit a wall...
The Problem With Light Microscope
No matter how sharp lenses were made, or cleverly aligned to capture light, it would only allow viewing of objects that were larger than “half the wavelength” of light. So, with light’s wavelength being 550nm, we could see objects larger than 200nm clearly. This limitation was mathematically calculated by Ernst Abbe in 1878 and came to be known as Abbe’s Limit.
But there was a whole world out there that was still invisible - the sizes of proteins and molecules that control a cell’s operation are 50-100 times smaller. Electron microscopes were invented. But the fact that the beam of electrons were very powerful and required a vacuum to operate meant scientists could not study live cells.
The Nanoscopic World
Enter Stefan Hell of the Max Planck Institute, Eric Betzig of the Howard Hughes Medical Institute, and William E. Moerner of Stanford. These three scientists used the ability to make molecules fluoresce (or glow) against a dark background, to make them visible.
Hell developed a technique where two lasers were used – one to light up the cell being observed, and the other to dim the glow from all but one nanometer region of the cell. So by scanning nanometer by nanometer, we could construct an image of the inside of the cell.
Meanwhile, William Moerner Stefan had found another way of lighting up a single molecule. He stained a molecule with a green fluorescent dye, and by shining lights of different wavelength on this molecule, he could “turn on” and “turn off” the glow.
Eric Betzig built up on Moerner’s idea. He stained different molecules with different colors and using the on-off mechanism, captured the glow from different regions. By putting the pictures together, he could create an image of the molecules.
Thanks to Hell, Betzig and Moerner, we can now see live cells divide, learn about the structures of proteins, observe nerve cells transmit information, and so much more. Their Nobel-winning work has furthered our understanding of the human body, and is helping us find cures for previously untreatable diseases.
Courtesy Salon, Nobelprize.org, inventors.about.com