Synthesis, Characterization, and Evaluation of Superparamagnetic Doped Ferrites as Potential Therapeutic Nanotools

Magnetic nanoparticles (MNPs) are one of the most promising candidates for their use as theranostic agents in the biomedical field due to their potential as contrast agents in magnetic resonance imaging (MRI) and also as heat generators in magnetic hyperthermia treatments. However, despite the large number of publications about this topic, just some few systematic studies about the influence of MNPs composition on their theranostic capabilities have been carried out. In this work, we show a detailed methodology for the preparation of highly monodisperse iron oxide-based MNPs with different cobalt, zinc, and manganese doping extents in the superparamagnetic regime. We aim to provide the tools to control the composition of the particles, as well as for their functionalization to make them highly stable in biological-mimicking media. Procedures to measure the capability of the particles as magnetothermal and MRI negative contrast agents as well as to analyze the influence of doping on such properties are also reported. In all experiments, the applied alternating magnetic fields were within the maximum allowed amplitude, frequency, and amplitude.frequency product range for potential validation of the experimental data toward the potential translation of the present MNPs to the clinical practice.