Through Genetic Engineering, a Single Cell Becomes a Laser Gun - PC Magazine

Scientists have created a "living laser," a single cell that emits laser light. Based on jellyfish DNA, the genetically engineered cell could someday lead to laser-armed cells that can treat themselves or other tissue in the body.

Created by Seok-Hyun Yun and Malte Gather from Harvard Medical School and Massachusetts General Hospital, the cellular laser was made possible via the same protein that gives jellyfish their glow, called green fluorescent protein (GFP). Taking mutant strain of GFP, called enhanced GFP (eGFP), that produces an even brighter glow, Yun and Gather genetically engineered it into an human kidney cell. They published their results in the journal Nature Photonics.

Regular lasers have two essential elements: a gain medium that amplifies the light and a optical system of mirrors to concentrate the light into a beam. With the eGFP-infused cell, the researchers had the first part, but for the second they had to put the cell in between two mirrors that were just 20 micrometers apart. For scale, a human hair is about 50 micrometers wide.

Now the cellular laser was ready. Yun and Gather stimulated it with pulses of blue light. At first, the cell emitted only ordinary fluorescence—until it crossed a threshold. Then the output suddenly changed, shooting out a beam of light that was "pure green" in color, higher in brightness, and in a directed manner (rather than diffuse).

"You can see it with the naked eye," Yun told Scientific American. "As soon as it reaches the threshold you can see it. It's a nice green."

Although the laser is weak compared to other lasers (like the laser weapons the Navy is building), a cellular-level laser opens up the possibility of operating lasers within a living organism. Yun suggests to Nature that his discovery could be used to build microscopic laser guns, which could be deployed in a patient to seek and destroy invaders or diseased cells. He says that cells that "self lase" could even be in the picture.

Such applications would face the problem of power and light generation as well as the development of practical nano-scale optical cavities, Yun says, so they're likely a long way off. Until then, the technique will likely be used to study cells themselves. When the light-happy cell emits a laser, the beam passes through the cell several times as it bounces between the mirrors, so if there are any abnormalities in the cell, it would affect the light.

"We are now trying to understand whether we can get any information about this cell through its optical properties," Yun says.

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