Facile synthesis of zinc ferrite nanoparticles as non-lanthanide T1 MRI contrast agents

Monodisperse ZnFe2O4 nanoparticles were synthesized using a simple and low-cost polyol process based on thermal decomposition of the precursors of Fe(acac)3 and Zn(acac)2 in triethylene glycol without any surfactant. The as-prepared ZnFe2O4 nanoparticles are highly crystalline, uniform in size, superparamagnetic and can be easily dispersed in aqueous media due to being coated by a layer of hydrophilic polyol ligands in situ. Magnetic study shown that the ZnFe2O4 nanoparticles had a low magnetic anisotropy and low magnetic moment compared to the conventional Fe3O4 nanoparticles. As a result, the as-prepared ZnFe2O4 nanoparticles provide an optimized r2/r1 ratio for T1-weighted magnetic resonance imaging (MRI) in the clinical field strength. A preliminary in vitro cytotoxicity test suggests that the zinc ferrite nanoparticles possess a good safety profile. Therefore, the as-prepared ZnFe2O4 nanoparticles have great potential to serve as a novel non-lanthanide T1 MRI contrast agent.