Controlled synthesis of water-dispersible and superparamagnetic Fe3O4 nanomaterials by a microwave-assisted solvothermal method: from nanocrystals to nanoclusters

摘要

Highly tunable Fe3O4 nanocrystals and nanoclusters with excellent water-dispersible and superp-aramagnetic properties were successfully synthesized in 3 h by a facile, effective microwave-assisted solvothermal method in ethylene glycol (EG). The effects of the main reaction conditions, including the weight ratio of FeCl3 center dot 6H(2)O to NaAc center dot 3H(2)O, the reaction temperature and time, on the size and morphology of the resulting products were systematically examined, and highly tunable superparamagnetic Fe3O4 nanocrystals (12-25 nm) and nanoclusters (40-90 nm) were selectively prepared. In addition, the morphology, structure, magnetic properties, and T-2 magnetic resonance (MR) contrast capability of these Fe3O4 nanomaterials were investigated. The optimized superparamagnetic iron oxide nanoparticle (SPION) crystals and SPION clusters exhibited remarkable saturation magnetization values of 78.4 and 75.2 emu g(-1) and excellent r(2) relaxivities of 101.05 and 100.68 mM(-1) s(-1), respectively. Therefore, the resulting Fe3O4 nanomaterials demonstrate immense potential as MR imaging (MRI) contrast agents. This simple, efficient approach can also be used to synthesize other water-dispersible nanomaterials with a tunable size and morphology, good reproducibility, and high product yield.