Synthesis of Radioiodinated Silica-Coated Magnetic Nanoparticles as SPECT/MR Dual-Modality Probe for Bone Imaging

Abstract Purpose A reliable imaging probe is essential for the accurate diagnosis of diseases and to support effective therapeutic decision-making. Different nanoparticles based multimodal probes have been studied for bone imaging. This work focuses on synthesizing of radiolabeled iron oxide magnetic nanoparticles as a promising dual modality bioprobe (SPECT/MR) for bone imaging. Methods In this work, silica coated magnetic nanoparticles (SiO 2 @MNPs) were synthesized. Radioiodination of SiO 2 @MNPs with iodine − 131 was performed via the Finkelstein reaction to produce a prospective radioiodinated MNPs for bone targeting. Results The radioiodinated NPs were obtained in high radiochemical purity (about 98.5 ± 0.5%) by magnet separation. The aqueous dispersion of the radioiodinated silica coated MNPs ( 131 I-SiO 2 @MNPs) exhibited adequate in-vitro stability and biocompatibility. Biodistribution study results after intravenous injection of ( 131 I-SiO 2 @MNPs) in normal mice revealed the high bone targeting efficiency of the radiolabeled NPs (C max = 6± 0.5% ID/g at t max = 2 h post injection). Magnetization properties measurements proved the preservation of the magnetic properties of SiO 2 @MNPs after the iodination process retaining its effectiveness as MRI contrast agent. Conclusion Based on to the results of this study, 131 I-SiO 2 @MNPs could be considered as a promising candidate for SPECT/MR dual bone imaging. Graphical Abstract