"The aerosol pyrolysis technique was used to produce carbon based nanostructures. Monocrystalline FeCo nanowires encapsulated inside multi-walled carbon nanotubes (MWNTs), centimeter-long strands of wide single walled carbon nanotubes (SWNTs), undoped MWNTs and nitrogen doped multi walled carbon nanotubes (CNx MWNTs) were fabricated. Strong capillary forces driven by the interaction of MWNTs and CNx MWNTs with organic solvents produced self-assembled nanotube cellular foams. The toxicological effects of MWNTs and CNx MWNTs in biological systems (mice and amoebas) were tested. CNx MWNTs appeared to be more biocompatible than undoped MWNTs, which exhibited an amoebicidal condition. These results encourage further studies testing CNx MWNTs as drug deliveries and cell transporters. Other applications of the synthesized nanomaterials will be discussed, such as the usage of FeCo filled MWNTs in the fabrication of high density magnetic storage devices."