It's become increasingly clear that the 21st century will be built with carbon nanotubes. EurekAlert lists yet another application for the plucky little singled-walled molecules: fluorescing biosensors:

"Carbon nanotubes naturally fluoresce in the near-infrared region of the spectrum where human tissue and biological fluids are particularly transparent," said Michael Strano, a professor of chemical and biomolecular engineering at [University of] Illinois [Urbana-Champaign]. "We have developed molecular sheaths around the nanotube that respond to a particular chemical and modulate the nanotube's optical properties."

The test setup was able to detect glucose levels, signaling changing concentration via changes in light when excited by a laser. Carbon nanotubes last longer in tissues than other fluorescing organic molecules, so they'll be more usable for extended monitoring. And the technique should work for a wide array of chemical types, allowing for extremely accurate health and environmental sensors.