Researchers have made use of human kidney cell to create the first living laser. Malte Gather and Seok Hyun Yun of the Wellman Center for Photomedicine at Massachusetts General Hospital, have described 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.
"Since they were first developed some 50 years ago, lasers have used synthetic materials such as crystals, dyes and purified gases as optical gain media, within which photon pulses are amplified as they bounces back and forth between two mirrors," Yun said.
"Ours is the first report of a successful biological laser based on a single, living cell," Yun added.
They developed a line of mammalian cells expressing GFP at the required levels. The cellular laser was assembled by placing a single GFP-expressing cell - with a diameter of from 15 to 20 millionths of a meter - 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 as in the GFP solution experiment, the researchers also found that 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.
"While the individual laser pulses last for only a few nanoseconds, they are bright enough to be readily detected and appear to carry very useful information that may give us new ways to analyze the properties of large numbers of cells almost instantaneously," said Yun, who is an associate professor of Dermatology at Harvard Medical School.
"And the ability to generate laser light from a biocompatible source placed inside a patient could be useful for photodynamic therapies, in which drugs are activated by the application of light, or novel forms of imaging," added Yun.
The report will appear in the journal Nature Photonics.