New electric double-layered magnetic fluids based on copper, nickel, and zinc ferrite nanostructures

We report on stable colloidal aqueous suspensions of magnetic nanostructure s made of copper, nickel, and zinc ferrites. These magnetic fluids could re present a new alternative for biological applications. The basic steps of t he nanoparticles synthesis, their chemical surface treatment, and their pep tization in a stable colloidal sol are given. Their chemical composition is carefully checked, and X-ray diffraction patterns provide both their mean size and a structural characterization. Magnetization results obtained at 3 00 K are presented and discussed.