Light from the dark

摘要

Fluorescence microscopy is the most popular way to image biomolecules, but it leaves many of them in the dark. Non-fluorescent, light-absorbing molecules can now be viewed by a method that turns them into mini-lasers. What happens when a molecule absorbs a photon from a beam of light? It moves from the ground state to an excited, higher-energy state and then quickly relaxes, giving off the absorbed energy as heat. There are, however, notable exceptions - molecules called fluoro-phores, which, after some 'wiggling', relax by emitting a lower-energy photon. Employed as molecular tags, fluorophores are invaluable in biomedical microscopy and diagnostics because they render dark molecules visible with high specificity.