An ultra-sensitive -weighted MR contrast agent based on Gd ion chelated FeO nanoparticles.

An ultra-sensitive -weighted MR imaging contrast agent was prepared based on FeO nanoparticles and Gd ions (FeO@Gd). Amino modified FeO nanoparticles were conjugated to diethylenetriamine pentaacetic acid, and finally coordinated with Gd ions. The nanoparticles had a uniform morphology with a size of 100 nm and a Gd/Fe mass ratio of 1/110. The (transverse relaxivity) of the FeO nanoparticles increased from 131.89 mM s to 202.06 mM s after coordination with Gd ions. MR measurements showed that the aqueous dispersion of FeO@Gd nanoparticles had an obvious concentration-dependent negative contrast enhancement. Hepatoma cells were selected to test the cytotoxicity and MR imaging effect. The application of FeO@Gd nanoparticles as contrast agents was also exploited for -weighted MR imaging of rat livers. All the results showed the effectiveness of the nanoparticles in MR diagnosis.