Lasers emit highly concentrated, amplified light. Usually it takes a complex array of crystals, gels or gases to amplify light particles, known as photons, as they bounce around between mirrors inside laser machines. But now scientists have found another way: using engineered living cells that can perform the feat.

The project took place at the Wellman Center for Photomedicine in Massachusetts. The key to this breakthrough involved the use of the widely studied protein known as green fluorescent protein (GFP). This protein, which was first discovered in jellyfish, has (as the name implies) the property of generating light.