Synthesis of PVP-coated ultra-small Fe3O4 nanoparticles as a MRI contrast agent.

Ultra-small Fe₃O₄ nanoparticles were prepared by using the coprecipitation method, in which the polyvinylpyrrolidone (PVP) serves as a stabilizer. The nanoparticles were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), infra spectrum (IR), X-ray photoelectron spectroscopy (XPS) and in vivo magnetic resonance imaging (MRI) test. The results showed that the particles’ size was determined by the dripping rate and that PVP molecules played the role of preventing the aggregation and restricting the size of Fe₃O₄ nanoparticles. The Fe₃O₄ nanoparticles with diameter from 6.5 to 1.9 nm obviously exhibited negative contrast enhancement and concentrated at the target area guided by a permanent magnet. [ABSTRACT FROM AUTHOR]