The behavior after intravenous injection in mice of multiwalled carbon nanotube / Fe3O4 hybrid MRI contrast agents

Fe3O4 nanoparticles were in situ loaded on the surface of multiwalled carbon nanotubes (MWCNTs) by a solvothermal method using diethylene glycol and diethanolamine as solvents and complexing agents. The as-prepared MWCNT/Fe3O4 hybrids exhibited excellent hydrophilicity, superparamagnetic property at room temperature, and a high T2 relaxivity of 175.5 mM−1 s−1 in aqueous solutions. In vitro experiments revealed that MWCNT/Fe3O4 had an excellent magnetic resonance imaging (MRI) enhancement effect on cancer cells, and importantly, they displayed low cytotoxicity and neglectable hemolytic activity. After intravenous administration, the T2-weighted MRI signal in the liver and spleen of mice decreased significantly, suggesting the potential application of the hybrids as MRI contrast agents. The organ biodistribution studies, histological analyses and elimination investigations showed that the hybrids were uptaken by the liver, lung and spleen after intravenous injection, and could be excreted from the liver and kidney.