Study of 223Ra uptake mechanism by Fe3O4 nanoparticles: towards new prospective theranostic SPIONs

The use of superparamagnetic iron oxide nanoparticles (SPIONs) and radiolabelled nanoparticles (NPs) has grown considerably over the recent years, and the SPIONs labelled with medicinal radionuclides offer new opportunities in multimodal diagnostics and in the drug-delivery systems for targeted alpha-particle therapy (TAT) driven by magnetic field gradient or by biologically active moieties bound on NPs shell. However, the mechanisms of NPs radiolabelling are not studied substantially and still remain unclear, even though the way of label attachment directly implies the stability of the label-nanoparticle construct. Since the Ra-223 was the first clinically approved alpha-emitter, it is a promising nuclide for further development of its targeted carriers. We report here on the study of Ra-223 uptake by the Fe3O4 SPIONs, together with an attempt to propose the Ra-223 uptake mechanism by the Fe3O4 NPs in the presence of a phosphate buffer a typical formulation medium, under the pseudo-equilibrium conditions. Further, the in vitro stability tests of the prepared [Ra-223]Fe3O4 NPs were performed to estimate the Ra-223 label stability. The potential use of Ra-223-labelled SPIONs in theranostic applications is also discussed.