Two scientists at Harvard Medical School, Malte Gather andSeok-Hyun Yun, managed to genetically enhance human kidney cellsand arrange them in a way that they could emit laser light. Despiteits early stage of development, such technology might later onserve for light-based therapies, e.g. activating previouslyadministered drugs that specifically target cancer cells in thebody.
Biological lasers appear even more attractive as conventionallasers many times use a laser medium that degrades over time withfrequent use. In the future, “we might be able to make self-healinglasers” where cells regenerate the laser medium themselves, saysGather.
LASERs (Light Amplification by Stimulated Emission of Radiation)have been around for a little more than 50 years serving in a widerange of applications from medicine over communication to industryproduction. To create highly focused laser beams, atoms ormolecules (so called gain media) are pumped into a higher-energystate with the help of electricity, chemicals or another laser.
De sleutel: proteine uit kwallen
Once ‘excited’, the gain medium emits photons that bounce backand forth inside an optical cavity. This optical cavity usuallyconsists of two highly reflective mirrors of which one is slightlymore transparent than the other. Bouncing back and forth, thephotons leave the optical cavity through the more transparentmirror as a highly focused laser beam.
Malte Gather and Seok-Hyun Yun applied this approach togenetically enhanced kidney cells with the help of greenfluorescent proteins (GFP). GFP was found in the 1960’s in thejellyfish Aequorea victoria and subsequently proved to beeasily reproducible by adding adequate DNA sequences to bodycells.
The US scientists took GFP enhanced kidney cells and arrangedthem tightly between two mirrors. Subsequently, they pumped the GFPinto a higher-energy state with the help of a blue-light laseremitting a low energy beam of 1 nanojoule. As with a regular laser,the gain medium GFP decayed and emitted photons that jumped backand forth in the optical cavity leaving it through the moretransparent mirror.