Scientists turn living cell into laser

For the first time, scientists have created a laser using a living cell.

To make this biological marvel, the researchers used a single human kidney cell, a bit of jellyfish protein, a couple mirrors and blue light.

A typical laser has a “gain medium” — a material that amplifies light given off by another source — and an “optical cavity” — mirrors set up in a way that lines up the light waves.

When the outside source of light is trained on the gain medium its atoms become excited and release photons.

As the photons ricochet between the mirrors, passing through the gain medium over and over again, they stimulate other atoms to release more photons. While the photons would normally exit in random directions the way light comes out of a flashlight, the mirrors direct the wavelengths into one beam, forming a laser.

The experiment

In this case, the researchers made their gain medium out of the jellyfish protein — green fluorescent protein (GFP) — which is what makes jellyfish bioluminescent and is widely used in cell biology to label cells.

They then engineered human embryonic kidney cells to produce GFP, and placed one such cell between two mirrors. They trained an outside source of blue light on the cell, which then emitted a laser beam visible with the naked eye.

Quoting researcher Seok-Hyun Yun, an optical physicist at Harvard Medical School and Massachusetts General Hospital in Boston, this Nature News article reports,

The width of the laser beam is “tiny” and “fairly weak” in its brightness compared to traditional lasers … but “an order of magnitude” brighter than natural jellyfish fluorescence, with a “beautiful green” colour.

Surprisingly, the laser didn’t harm the cell in the process — quite a feat considering that even the earliest lasers could drill holes in razor blades.

The future of living lasers

A living laser could have numerous scientific applications, say Yun and co-author Malte Gather, who published their study in Nature Photonics.

Cell biologists could use living lasers to study the structure of cells. As seen in the photo, the cell produces light in an irregular pattern which scientists could study to determine the internal structure of the cell.

Living lasers could be useful in biotechnology and medicine, to create drugs that are activated by light or to treat disease by attacking cells deep within the body. But the main challenge to developing such internal applications is providing the initial outside source of light.

In a press release, Gather says,

“One of our long-term goals will be finding ways to bring optical communications and computing, currently done with inanimate electronic devices, into the realm of biotechnology. That could be particularly useful in projects requiring the interfacing of electronics with biological organisms. We also hope to be able to implant a structure equivalent to the mirrored chamber right into a cell, which would the next milestone in this research.”

Photo: Microscope image of a single-cell living laser in action. (Nature Photonics and Malte Gather, Wellman Center for Photomedicine, Mass. General Hospital.)