What's the News: Scientists have developed the first biological laser, made from a single living cell. This "living laser," described in a new study in Nature Photonics, could one day lead to better medical imaging and light-based treatments for cancer or other diseases. How the Heck:
Lasers typically have several parts: a material called a gain medium, which amplifies light; an energy source to "pump" the gain medium, exciting its atoms and enabling it to emit more powerful light; and mirrors, which direct the light into a coherent beam.
To start, the researchers modified cells derived from a human kidney to manufacture green fluorescent protein, or GFP, a molecule that glows green when exposed to blue light. This glowing cell served as the laser's gain medium.
The researchers then nestled the cell between two mirrors, which were close enough together to form a cell-sized cavity, and shone pulses of blue light---the energy source---onto the cell through a microscope.
Blue light would simply make the cell glow, under normal conditions. In this mirrored cavity, however, the photons bounced around, exciting more GFP molecules. This meant the cell could amplify the light---eventually emitting a green laser beam more powerful than the blue light that pumped it. The cell was able to emit a few hundred laser pulses over several minutes before its GFP wore out.
The cell survived without any significant damage. Plus, as it kept producing GFP, it's likely it could repair its light-amplifying abilities and live to lase again.
What's the Context:
While this is the first cellular laser, it isn't the first unorthodox one. Other scientists have made lasers from gelatin and from ethyl alcohols--namely rum, vodka, and gin.
GFP, first found in jellyfish in the 1960s, is a ubiquitous research tool, used for everything from tracking cells' inner workings to making monkeys glow. Three researchers earned a Nobel Prize in 2008 for their work with GFP---though the researcher who discovered the gene for the protein did not.
The Future Holds:
Biological lasers have several potential applications. They could improve biological imaging, since it's often difficult for light to penetrate living tissue. They could enable new types of light-based therapeutics, which use light to fight disease by, for instance, triggering a cancer-fighting drug. They could even be used to make better brain-computer interfaces, letting laser-emitting neurons communicate more easily with neural prosthetics or other electrical implants.
The researchers also hope to integrate structures that take on the mirrors' role into the cell, making each cell a stand-alone laser.
Reference: Malte C. Gather & Seok Hyun Yun. "Single-cell biological lasers." Nature Photonics, June 12, 2011. DOI:10.1038/nphoton.2011.99Image: Malte Gather
