Magnetic and relaxometric properties of polyethylenimine-coated superparamagnetic MRI contrast agents

• Published in: Journal of magnetism and magnetic materials 2008-07, Vol.320 (14), p.e316-e319
• Main Authors: Corti, M., Lascialfari, A., Marinone, M., Masotti, A., Micotti, E., Orsini, F., Ortaggi, G., Poletti, G., Innocenti, C., Sangregorio, C.
• Format: Article
• Language: English
• Subjects: Magnetic property and nuclear magnetic resonance; Nanoparticle; Organic compound; Polymer; Polymer surface
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2008.02.115

Novel systems to be employed as superparamagnetic contrast agents (CA) for magnetic resonance imaging (MRI) have been synthesized. These compounds are composed of an iron oxide magnetic core coated by polyethylenimine (PEI) or carboxylated polyethylenimine (PEI-COOH). The aim of the present work was to prepare and study new nanostructured systems (with better or at least comparable relaxivities, R 1 and R 2, with respect to the commercial ones) with controlled, almost monodisperse average dimensions and shape, as candidates for molecular targeting. By means of atomic force microscopy (AFM) measurements we determined the average diameter, of the order of 200 nm, and the shape of the particles. The superparamagnetic behavior was assessed by SQUID measurements. From X-ray data the estimated average diameters of the magnetic cores were found to be ∼5.8 nm for PEI-COOH60 and ∼20 nm for the compound named PEI25. By NMR-dispersion (NMRD), we found that PEI-COOH60 presents R 1 and R 2 relaxivities slightly lower than Endorem ®. The experimental results suggest that these novel compounds can be used as MRI CA.