According to Wired News, UC-Riverside scientists are working on repairing bones by using carbon nanotubes.
Human bones are both organic and inorganic. The organic part is made of collagen, the most abundant protein in mammals. The inorganic component is hydroxyapatite, a type of calcium crystal. The collagen forms a sort of natural scaffold over which the calcium crystals organize into bone. The idea in Haddon's research is to use the nanotubes as substitutes for the collagen to promote new bone growth when bones have been broken or worn down.
The appeal of nanotubes is their mechanical strength: they are intrinsically stronger than any other fiber in nature, and much lighter than most. The researchers have altered the chemistry of the ends of the nanotubes so that they attract hydroxyapatite.
My favorite quote:
Haddon hopes soon to test how the human body will respond to carbon nanotubes. Even though humans are carbon-based, that's not an iron-clad guarantee that the two will get along smoothly.