Scientists turn human cells into lasers

Scientists in the US have for the first time induced a living human cell to emit a laser beam - a feat they accomplished with the help of jellyfish protein.

Lasers are a form of purified and intense light. Creating a laser beam requires some kind of 'gain medium' – a material that amplifies light – and an 'optical cavity' – a series of mirrors arranged in such a way as to concentrate the light and align it into a single beam.

Until now, gain media have consisted mostly of gas or plasma trapped in some kind of inorganic container. But for this new experiment, reported in Nature Photonics, scientists employed green fluorescent protein (GFP), a substance that creatures such as jellyfish use to glow in the dark.

Malte Gather and Seok Hyun Yun of the Massachusetts General Hospital in the United States genetically engineered human kidney cells to produce GFP. These cells were to act as the gain medium. To create a laser these cells were put, one at a time, in an optical cavity, which consisted of two tiny mirrors, 20 micrometres across.

The scientists then shone blue light onto the modified kidney cell, which induced it to emit a "beautiful green" laser beam. Amazingly, despite being turned into lasers, the cells were unharmed.  

"This is the first time that we have used biological materials to build a laser and generate light from something that is living," said Yun, an optical physicist.

Thoughts of the US military spawning a race of genetically engineered soldiers able to fire laser beams from their kidneys can for the moment be set aside. The scientists say that the green laser produced is "fairly weak" compared to traditional, inorganic, lasers.

More realistic applications, once the techniques have been perfected, could include turning individual human cells into lasers. The properties of the light they emit can then be used to determine what is happening in the cell. ·