Fireflies have recently proved beneficial to the medical world. The enzyme that makes them glow is paving the way for a long-sought new medical imaging agent to better monitor treatment with heparin, a blood thinner prescribed to millions of people for treating or preventing blood clots, scientists said. Researchers at Connecticut College described a need for new medical imaging agents that emit near-infrared light – the same light rays used in night-vision technology to allow soldiers to see in the dark. With the ability to penetrate deep into the body, those rays could provide doctors with a better way of detecting the proteins involved in blood clotting. Luciferase, the enzyme that makes lightning bugs glow, is already being used in laboratory research. The new study, however, makes advances toward using luciferase in medical imaging. The scientists combined a protein from the firefly luciferase with a special dye that allowed the protein to emit near-IR light. In laboratory experiments, the material detected trace amounts of a specific blood protein, called factor Xa, which is used to monitor the effectiveness of heparin treatment. The findings are promising for improved heparin therapy monitoring. The study appeared in the American Chemical Society’s monthly journal Bioconjugate Chemistry, Vol. 21, pp. 2023-2030 (2010). Research was funded by the US Air Force Office of Scientific Research, the National Science Foundation and the Hans & Ella McCollum ’21 Vahlteich Endowment.