Mn-Zn ferrite nanoparticles with silica and titania coatings: Synthesis, transverse relaxivity, and cytotoxicity

The 11nm Mn-Zn ferrite nanoparticles are synthesized under hydrothermal conditions and and small clusters of crystallites are subsequently encapsulated into silica and titania. XRD, combined with hydrothermal treatment of the titania-coated product, demonstrates that the coating is amorphous but can be easily transformed into anatase. The colloidal behaviour and stability of nanoparticles in water is evidenced by DLS and the measurements of zeta potential, whose negative values lead to strong Coulombic repulsion among coated particles. Magnetic measurements show high magnetization of cores and superparamagnetic state at 300 K. The relaxometric study on aqueous suspensions in 0.5 and 11.75 T magnetic fields reveals high transverse relaxivity and two distinct forms of its temperature dependence. In the studied range of concentrations, the viability and proliferation of A549 suspension cells are not affected, and only negligible effects are detected in the cell index of adherent cells.