Synthesis of magnetic mesoporous nanocomposites: A promising candidate for diagnostic and therapeutic biomedical applications

Abstract

In the present research, iron oxide nanoparticles were synthesized through the hydrothermal method, and the influence of processing parameters such as pH of the initial coprecipitation reaction, time and temperature of hydrothermal treatment was studied. The magnetic iron oxide nanoparticles were coated with a negatively charged, thin layer of silica. The product is then coated with a layer of mesoporous silica. As a result of the electrostatic attraction between the cationic CTAB and the primary silica coating, the formation of mesoporous silica would be mainly localized on the surface of nanoparticles. Calcination was performed in an argon atmosphere tube furnace at 550 °C, through which CTAB was decomposed and eliminated thoroughly from the structure, thereby leaving the oriented pore structure behind. The effects of synthesis parameters such as the ethanol/water volume ratio, the amount of catalyst needed for the sol–gel reaction, and the molar ratio of TEOS/CTAB on the synthesized nanocomposite were investigated. FESEM observations were used to define the morphology and approximate particle size of the product. The FTIR analysis confirmed the formation of Si–O–Fe bonds as a proof for the core/shell morphology of the nanocomposite particles. The nitrogen adsorption behavior through the BET method proved the presence of mesopores in the magnetic nanocomposite. The specific surface area of the nanocomposite varied with the amount of CTAB in the range of 212–295 m2/g. The magnetic mesoporous nanocomposite possessed a considerable magnetic saturation of 30 emu/g, while the final mean diameter of the nanoparticles was about 42 nm.