Silica/Ormosil SPIONs for Biomedical Applications

In the present work, magnetic nanoparticles coated with silica or ORMOSIL are prepared in a two step process. In the first step, SPIONs with 6 nm average diameter are produced by a reduction-precipitation process conducted in air and in the second one, SPIONs were used as seeds for silica/ORMOSIL growth (below 30 nm), in situ by a modified Stober sol-gel method. SPIONs and silica/ ORMOSIL magnetic core-shell nanostructures were characterized by X-Ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), Mossbauer spectroscopy and SQUID magnetometry. TEM observations of SPIONs and silica/ORMOSIL SPIONs allow determining size and shape. FTIR allows determining silica/ORMOSIL structural fingerprints. X-ray and Mossbauer spectroscopy allow determining the magnetite/maghemite ratio, discussed as a nanosized constrained. SPIONs and silica/ORMOSIL SPIONs show superparamagnetic properties making them appropriated to biomedical applications.