Scientists Engineer Cells That Act As Bio-Lasers

Scientists have genetically-engineered bio lasers: cells that express green fluorescent protein (GFP) and generate pulses of laser light.

AsianScientist (Jun. 12, 2011) – In a letter published today in Nature Photonics, researchers describe how a single cell genetically-engineered to express green fluorescent protein (GFP) can be used to amplify the light particles called photons into nanosecond-long pulses of laser light.

“Ours is the first report of a successful biological laser based on a single, living cell,” says Seok Hyun Yun, corresponding author of the report and Associate Professor of Dermatology at Harvard Medical School.

Malte Gather, the lead author on the paper, said the motivation of the project was a basic scientific curiosity as to why laser light does not occur in nature, and whether they could find a way to achieve lasing in biological substances or living organisms.

The investigators, both from the Wellman Center for Photomedicine at Massachusetts General Hospital, chose GFP for its well-established properties and techniques.

To determine the protein’s potential for generating laser light, they first assembled a device consisting of an inch-long cylinder, with mirrors at each end, filled with a solution of GFP in water. After first confirming that the GFP solution could amplify input energy into brief pulses of laser light, the researchers estimated the concentration of GFP required to produce the laser effect.

Next, they developed mammalian cells expressing GFP at the required levels. The cellular laser was assembled by placing a single GFP-expressing cell in a microcavity consisting of two highly reflective mirrors spaced 20 millionths of a meter apart.

Not only did the cell-based device produce pulses of laser light, the spherical shape of the cell itself acted as a lens, refocusing the light and inducing emission of laser light at lower energy levels than required for the solution-based device. The cells used in the device survived the lasing process and were able to continue producing hundreds of pulses of laser light.

The ability to generate laser light from a biocompatible source placed inside a patient may someday be useful for photodynamic therapies, in which drugs are activated by the application of light, or novel forms of imaging, said Yun.

As for their future directions, one of their 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.

They 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.

The article can be found at: Gather MC et al. (2011) Single-cell biological lasers.

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Source: Massachusetts General Hospital, Nature Publishing Group.
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