Preparation of composite with silica-coated nanoparticles of iron oxide spinels for applications based on magnetically induced hyperthermia.

It is reported a novel method to prepare magnetic core (iron oxide spinels)?shell (silica) composites containing well-dispersed magnetic nanoparticles in aqueous solution. The synthetic process consists of two steps. In a first step, iron oxide nanoparticles obtained through co-precipitation are dispersed in an aqueous solution containing tetramethylammonium hydroxide; in a second step, particles of this sample are coated with silica, through hydrolyzation of tetraethyl orthosilicate. The intrinsic atomic structure and essential properties of the core?shell system were assessed with powder X-ray diffraction, Fourier transform infrared spectrometry, M?ssbauer spectroscopy and transmission electron microscopy. The heat released by this ferrofluid under an AC-generated magnetic field was evaluated by following the temperature evolution under increasingmagnetic field strengths.Results strongly indicate that this ferrofluid based on silica-coated iron oxide spinels is technologically a very promising material to be used in medical practices, in oncology