It seems like carbon nanotubes are capable of doing just about anything we ask them to, from making space elevators a reality to ushering in the next generation of energy storage systems. They also have lots of biological applications, and researchers at Stanford are using fluorescent ones to see inside the bodies of living animals.
Carbon nanotubes have been used for a while to deliver drugs to treat things like cancer, but a group at Stanford thought that it would be extra helpful if it was somehow possible to watch where the nanotubes were going to make sure that they were hitting their targets. In the past, biocompatible organic fluorescent dyes have been used for this purpose, but the problem is that these dyes can get mixed up with biological tissues, making images come out blurry.
Nanotubes, however, fluoresce at an entirely different wavelength, so biological tissues don't get in the way at all. By feeding a mouse medication attached to nanotubes and then shining a laser on its skin, the researchers found that they could track the nanotubes in an impressive amount of detail. It's possible to resolve individual organs, and even organs that are behind other organs, like the pancreas, which I'm sure is somehow vital to our survival.
This technique can't get as much detail as something like a CT scan or an MRI, but it also doesn't involve potentially harmful radiation or super expensive equipment. All you really need are the nanotubes, a camera that can see into the near-infrared, and a laser, and there you go, living tissues are now effectively transparent.