14 DAY TRIAL // Harvard University scientists announce the creation of a new type of laser, which is made out of living cells injected with a special protein. The cells can remain alive even as they produce the amplified light, the team reports.
Generally, laser light is produced when a light source is bounced back and forth between two mirrors. The signals is excited, and certain wavelengths are amplified, and then focused in a narrow beam of light, that is then ejected from the amplifier.
In other, non-laser light sources, atoms are simply excited by flash tubes or electrical discharges, releasing photons into the environment. The beams are not focused, such as for example in flashlights.
But Harvard experts Malte Gather and Seok-Hyun Yun were eager to take laser technology a step further, so they decided to test and see whether a single, living cell could be used as a light source.
They injected a cell with a marker called the green fluorescent protein (GFP), which was only a few years ago isolated from jellyfish. The molecule glows green when blue light is shone on it.
Martin Chalfie, Osamu Shimomura, and Roger Y. Tsien, the scientists who discovered and refined the GFP, were awarded the Nobel Prize in Chemistry on October 10, 2008, for their work,
By injecting a single mammalian cell with a loop of DNA coding for an enhanced form of GFP, Gather and Yun were able to create the perfect gain medium for their experiments. The augmented cell was then placed between two semi-transparent mirrors.
The next step was exposing the medium to fast and intense pulses of blue light, which made the GFP marker glow. As the light pulses intensified, certain wavelengths of the green light were amplified to such an extent that they eventually burst through the mirrors in the form of laser light.
Even after a few minutes of exposing the medium to intense blue light, the cell was still alive, and carrying out its vital functions as if nothing had happened. “We would like to have a laser inside the body of the animal, to generate laser light directly within the animal's tissue,” Yun explains.
The innovative work could also lead to the development of an advanced form of laser optical tomography, an investigations technique in which laser light can reveal the size, depth and volume of biological tissue samples.
At this time, the method uses external laser sources, but its resolution could be improved by using laser light produced by the target cells themselves, Daily Galaxy reports.
“Previously the laser was considered an engineering material, and now we are showing the concept of the laser can be integrated into biological systems,” Yun concludes.