Magnetic SiO2 - Mn1-xCoxFe2O4 nanocomposites decorated with Au@Fe3O4 nanoparticles for hyperthermia

The design of multicore magnetic nanocomposites for hyperthermia therapy is still far from being optimized due to the variable performance found in many iron oxide nanostructure systems. Herein, we present a reproducible synthesis of magnetic mixed manganese-cobalt ferrite nanoparticles Mn1-xCoxFe2O4 (0 <= x <= 1) coated with silica (SiO2) and decorated with Au@Fe3O4 nanoparticles as magnetic fluid hyperthermia heat mediators, employing a hydrogel as a tissue-equivalent. Mn1-xCoxFe2O4 NPs were synthesized using the thermal decomposition method, then coated with SiO2 following the Stober method and decorated with Au@Fe3O4 nanoparticles. Structural characterization was carried out applying X-ray diffraction (XRD), infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). Magnetic properties as a function of the Mn+2 content were studied using a vibrating sample magnetometer (VSM) at room temperature. Hyperthermia investigations were performed at 454 +/- 20 kHz with a magnetic field amplitude of up to 5.5 mT. The specific absorption rate (SAR) values of the nanocomposites were found to have increased with the Au@Fe3O4 decoration in water. The advantage of the designed nanocomposite system lies in the fact that versatile combinations of magnetic NPs, SiO2 and Au@Fe3O4 can change the magnetic properties to optimize the Specific Absorption Rate (SAR).