Hybrid Magnetite‐Gadolinium Nanostructures for Multimodal Diagnostics: Screening Possible Routes of Synthesis

The design of hybrid nanoparticles has received considerable attention in recent years, particularly for biomedical applications. For their design, iron oxide magnetic nanoparticles (MNPs) are of particular interest because of their distinctive properties, such as superparamagnetism. The combination of MNPs with gadolinium compounds would offer a nanoplatform suitable as theranostics: a nanosystem capable of transporting the diagnostic and therapeutic agent in the same nanostructure. The present work studied the modification of MNPs with gadolinium oxide and gadolinium borate. Polyethyleneimine‐stabilized MNPs were modified with the gadolinium compounds through a hydrothermal treatment. Two hybrid nanosystems were obtained: Mag@Gd ₂ O ₃ and Mag@GdBO ₃ . The complete characterization of these hybrids was analyzed by means of X‐ray diffraction, infrared spectroscopy, transmission electron microscopy, and scanning electron microscopy with an energy‐dispersive X‐ray microanalysis system. The stability of the nanohybrids was evaluated regarding the leaching of gadolinium ions in an aqueous medium. Moreover, the nanosystems were assayed for their performance in magnetic particle imaging (MPI), which is an emerging imaging technique. Hyperthermia capability was also assayed. The assays were performed with MNPs and hybrid nanoparticles, demonstrating that, despite the presence of the gadolinium, the MNPs maintain their properties.