Iron Oxide Nanoparticles as MRI Contrast Agents: a Physico-chemical Insight

SuperParamagnetic Iron Oxide Nanoparticles (SPIONs) are effective contrast agents for Magnetic Resonance Imaging. The modification of SPION surface has emerged as imperative to induce stability in aqueous media and biocompatibility. On the grounds of the published literature, we optimized a robust strategy for the preparation of SPION aqueous suspension suitable for biocompatible applications. The functionalization strategy was applied to SPIONs synthesized through thermal-decomposition method, but, in principle, it can also be extended to other inorganic nanoparticles. A detailed description of the preparation protocols adopted for the obtainment of functionalized SPIONs is reported together with a detailed characterization of their structure and composition. As a result, monodispersed functionalized SPIONs with high biocompatibility and effective activity as MRI contrast agents were obtained. Nevertheless, reliable information is often required about the behavior of nanoparticles in biological systems. For this purpose, the interaction between the functionalized SPIONs and lipid bilayers mimicking of the plasma cellular membrane was characterized. Finally, as a further step in the development of functionalized SPIONs for biomedical applications, the versatility of the optimized functionalization strategy was exploited to prepare prototypes of theranostic nanoparticles as well as dualmodal imaging contrast agents.