Synthesis of amine-stabilized aqueous colloidal iron oxide nanoparticles

We demonstrate a simple one-step process for the synthesis of iron oxide nanoparticle aqueous colloids using the multifunctional molecule dodecylamine (DDA), which electrostatically complexes with aqueous iron ions (one precursor Fe2+ from FeCl2), reduces them, and subsequently caps the nanoparticles. The iron oxide particles thus synthesized are of the face-centered cubic (FCC) phase with a high degree of monodispersity and an appropriate concentration of the amine-capping molecular layer. The aqueous magnetic nanocrystalline colloids were characterized by TEM, XRD, XPS, TGA/DTA, and FTIR spectroscopy techniques. The relaxivity, stability, and hydrodynamic size of the nanoparticles were investigated for potential application in magnetic resonance imaging (MRI). The magnetic properties were also studied by using a superconducting quantum interference device (SQUID) magnetometer at room temperature. We believe that such a simple one-step synthesis of biocompatible aqueous nanomagnetic colloids will have viable applications in biomedical imaging, diagnostics, and therapeutics.