Translocation and fate of multi-walled carbon nanotubes in vivo

Carbon nanotube (CNT) mediated delivery system of drugs etc. has currently aroused a large interest. Because the delivery system will be ultimately introduced into the human body, the information about the in vivo biological behavior and consequences of CNTs becomes very important. Here, using [14C-taurine]-multi-walled CNTs (MWCNTs) as tracers, we show the biodistribution and translocation pathways of MWCNTs in mice by three different routes. After mice were exposed by intravenous injection, MWCNTs predominately accumulated in liver and retained for long time. Transmission electron micrographs clearly show the remarkable entrapment of MWCNTs in hepatic macrophages (Kupffer cells). The biological index examinations indicate low liver acute toxicity of MWCNTs. Some favorable aspects of MWCNTs being used as a drug nanovehicle are also discussed.