Metal substituted ferrite nanoparticles (MexFe3-xO4, Me = Mn, Co, Ni, and Zn, etc.) have been utilized in a variety of biomedical applications, including magnetic hyperthermia, drug delivery, and magnetic resonance imaging (MRI) contrast agents. Additional applications include magnetic induction for selective reduction of CO2, high frequency inductors for energy conversion, and environmental remediation tools. In most these applications the likelihood of success is dependent upon the magnetic properties of these composite materials. The most significant magnetic properties include magnetic saturation and magnetic anisotropy. For these materials, those properties are most depended on the composition of the ferrite core. Therefore, by manipulating the atomic composition, materials can be intelligently designed to have the appropriate magnetic properties for a given application. Normally, to produce such materials is a rather Edistonian where multiple samples synthesized and characterized seeking the optimal composition. For this work we have utilized Density Functional Theory (DFT) to learn the relationship between composition and magnetic performance of substituted ferrites. Magnetic saturations and anisotropies are calculated for ~1,000 substituted ferrite bulk structures (with x ranging from 0.0625 to 1) using DFT. Substitutions are made at the octahedrally coordinated Fe2+ sites. To produce multi-dopant ferrite nanoparticles, the 'Extended LaMer' and seed-mediated growth techniques were combined by first utilizing traditional thermal decomposition of metal acetylacetonates to produce seed particles, followed by a continuous injection of metal oleate precursors to increase the volume of the seed particles. With the choice of precursors for the seeding and dripping stage. Combining transmission electron microscopy, energy-dispersive x-ray spectroscopy, x-ray diffraction, and vibrating sample magnetometry, we conclude that the seed-mediated drip method is a viable method to produce multi-dopant ferrite nanoparticles. Finally, the effect of stabilizing polymer brushes on the surface of the nanocomposites will be discussed. Specially, calculations of the energetics between the particles accounting for the magnetic interactions are applied to determine the molecular weight of the stabilizing polymer brush. In addition, surface moieties for additional imaging, therapy, and targeting will be covered as avenues of investigation.

Synthesis of polymer modified substituted ferrite nanomaterials guided by density functional theory.

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