Synthesis of Fe3O4/APTES/PEG diacid functionalized magnetic nanoparticles for MR imaging

The magnetite (Fe3O4) nanoparticles (MNPs) coated with PEG diacid via covalent bonds were prepared for magnetic resonance imaging (MRI). The surface of MNPs was first coated with (3-aminopropyl) triethoxysilane (APTES) by a silanization reaction and then linked with PEG diacid via the reaction between –NH2 and –COOH to form well-dispersed surface functionalized biocompatible MNPs. The obtained nanoparticles were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and thermogravimetry (TG). The MNPs had an average size of 20 nm and exhibited superparamagnetism and high saturation magnetization at room temperature. In addition, PEG-6000 diacid coated Fe3O4 nanoparticles were used to perform the MRI experiments on the living rabbits with VX2 malignant tumor, the results showed that these nanoparticles appear to be a promising vehicle for MR imaging.