In this study, we have succeeded in synthesizing and characterizing a water-soluble multi-walled carbon nanotube. Carbon nanotubes have been functionalized with many hydrophilic carboxylic groups on the surface (3-10 wt%) by a poly-carboxylation reaction and the obtained products show stable aqueous dispersion. To examine the nanotubefs preliminary biocompatibility, we injected the functionalized carbon nanotube solution into mice through the tail vein. The time-profile of the subjectsf body weight had a similar tendency to that of mice in a control group during 4-week post-injection examination. The injected carbon nanotube derivatives were observed in specimens of the lung and liver using a transmission electron microscope. These results suggest that the in-jected carbon nanotubes reach some organs through blood circulation after injection but they did not cause serious acute toxicity in mice.
Key words: multi-walled carbon nanotube, poly-carboxylation reaction, water-soluble, biodistribution