Iron oxide-silica nanocomposites yielded by chemical route and sol–gel method

Magnetic nanoparticles yielded by chemical route were surface modified with stabilizing agents being further coated by sol–gel method with silica shell to be used for various applications. Iron oxide magnetic cores were dispersed in water by single citrate layer and, respectively, by double oleate hydrophilic coating. Sol–gel reaction with tetraethylorthosilicate provided further coating with silica that confers increased reactivity for ligand coupling. Microstructural and magnetic properties were investigated by standard methods evidencing nanometric size, good crystallinity, and superparamagnetic behavior. Comparative analysis evidenced similar crystallite size for both citrate- and oleate-coated magnetic nanoparticles, while granularity was changed after silica adding. Saturation magnetization diminished less for oleate-stabilized nanoparticles than for citrate-stabilized ones after silica coating and moderate thermal treatment. Such prepared magnetic nanocomposites could have possible utilization as magnetic vectors for targeted biomolecules. Graphical Abstract