Improving magnetic properties of Mn- and Zn-doped core-shell iron oxide nanoparticles by tuning their size

Superparamagnetic iron oxide nanoparticles (SPIONs) offer promising applications in nanomedicine due to their appealing properties. Their magnetic and magnetic hyperthermia properties are considered as relevant tools for low invasive cancer therapeutic applications. In this work, we report on the synthesis of polyhedral core-shell SPIONs. Their size was tuned to improve their magnetic properties. Furthermore, by hybridizing into a core-shell inorganic/inorganic structure, the nanoparticles can achieve significantly improved magnetic-to-thermal energy conversion efficiency (at least tenfold). The designed core NPs are composed of a Zn_0.4Fe_2.6O₄ core and a MnFe₂O₄ shell. Their size and morphology were determined by transmission electron microscopy, Fourier-transform infrared spectroscopy was used to investigate their chemical composition. The iron oxide phase was confirmed by Mössbauer analysis, and the magnetic properties were studied to select the ideal size for magnetic hyperthermia application.