Synthesis and Characterization of Tb‐Doped Nanoferrites

Abstract Tb³⁺‐substituted superparamagnetic iron‐oxide‐based nanoparticles (NPs) that can be promising for possible multimodal drug carrier and radiotherapy are presented. These NPs were obtained using a reverse micelle template method with controlled micelle size. The atomic ratio of Tb/Fe ions was found to be very close to that expected from the stoichiometry of the reagents used. Aqueous suspensions of Tb‐doped nanoferrites are emissive with emission peaks characteristic for the Tb³⁺ dopant. Time‐resolved fluorescence decay data revealed two populations occupying inequivalent matrix sites. Above 80 K the Tb‐doped nanoferrites were superparamagnetic, which is a prerequisite for their use as carriers in magnetic‐field‐driven targeted therapies. The incorporation of up to 15 at.% of Tb³⁺ in their core resulted in a decrease of magnetization. Nevertheless, this magnetization appears to be sufficient for their use as carriers in an external magnetic field, and, of equal importance, stable isotope ¹⁵⁹Tb³⁺ could be replaced by radioactive ¹⁶¹Tb³⁺, yielding multimodal NPs, suitable for conjugated therapies such as radiotherapy and magnetothermal therapy, as well as targeted drug delivery.