Monodisperse water-soluble -Fe2O3/polyvinylpyrrolidone nanoparticles for a magnetic resonance imaging contrast agent

Water-soluble γ-Fe2O3/polyvinylpyrrolidone (PVP) nanoparticles were obtained by transferring oleic acid (OA) coated iron-oxide nanocrystals from hexane to water. The particle size of the γ-Fe2O3/PVP nanoparticles with excellent monodispersity is about 14 nm. Fourier transform-infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) results indicate that PVP anchors on the γ-Fe2O3 nanoparticles through its carbonyl group and provided sufficient hydrophilicity. The maghemite content in the γ-Fe2O3/PVP nanoparticles was about 81 wt-%. The saturation magnetisation of the superparamagnetic γ-Fe2O3/PVP nanoparticles is 57·7 emu g− 1 at 295 K. For in vivo magnetic resonance imaging (MRI) studies, the γ-Fe2O3/PVP nanoparticles can be guided to the target area by a permanent magnet and show negative contrast enhancement on the target area of laboratory mice.