Synthesis and characterization of PVP-functionalized superparamagnetic Fe3O4 nanoparticles as an MRI contrast agent

Abstract

The magnetite (Fe3O4) nanoparticles (MNPs) coated with poly(N-vinyl pyrrolidone) (PVP) via covalent bonds were prepared as T2 contrast agent for magnetic resonance imaging (MRI). The surface of MNPs was first coated with 3- (trimethoxysilyl) propyl methacrylate (silan A) by a silanization reaction to introduce reactive vinyl groups onto the sur- face, then poly(N-vinyl pyrrolidone) was grafted onto the surface of modified-MNPs via surface-initiated radical polymerization. The obtained nanoparticles were characterized by FT-IR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), TEM (transmission electron microscopy), VSM (vibrating sample magnetometer), and TGA (thermo- gravimetric analysis). The MNPs had an average size of 14 nm and exhibited superparamagnetism and high saturation mag- netization at room temperature. T2-weighted MRI images of PVP-grafted MNPs showed that the magnetic resonance signal is enhanced significantly with increasing nanoparticle concentration in water. The r1 and r2 values per millimole Fe, and r2/r1 value of the PVP-grafted MNPs were calculated to be 2.6 , 72.1, and 28.1(mmol/l) -1 ·s -1 , respectively. These results indicate that the PVP-grafted MNPs have great potential for application in MRI as a T2 contrast agent.