Fireflies have mirrored photocells that reflect the light emitted by the luciferase reaction so that none of it is wasted and all of it leaves the firefly. Malte Gather and Seok-Hyun Yun of Harvard Medical School have one-upped the firefly, they have taken a single eGFP expressing kidney cell and placed it in a reflective optical cavity. When the GFP is excited by a low energy (~ 1 nanojoule) blue laser the emitted green fluorescence bounces around the reflective optical cavity, amplifying the fluorescence until it is released in a coherent beam of green light -the cell acts as a laser. Lasers were invented just over 50 years ago, this is the first living laser. Currently there are no uses for the biolaser, however there are many potential uses and I am sure it won’t be long before we will read about the first ones.
Illustration of the single-cell laser. (Nature Photonics 2011)