An Efficient Route to Rattle-Type Fe₃O₄@SiO₂ Hollow Mesoporous Spheres Using Colloidal Carbon Spheres Templates

Rattle-type Fe 3 O 4 @SiO 2 hollow mesoporous spheres with large cavities have been successfully prepared by using the colloidal carbon spheres as the templates. The spheres are well monodisperse and nearly uniform in dimension with particle size of ca. 900 nm. The thickness of the mesoporous silica shell is about 100 nm, and only one Fe 3 O 4 particle of ca. 100 nm in diameter is encapsulated in each hollow mesoporous silica sphere. The magnetic measurement indicated that the Fe 3 O 4 @SiO 2 hollow mesoporous spheres exhibited ferromagnetic behavior with the magnetization saturation of 1.6 emu/g. Using aspirin as a model drug, the Fe 3 O 4 @SiO 2 hollow mesoporous spheres showed high drug loading capacity and sustained release property. Therefore, this kind of magnetic hollow mesoporous spheres provides a very promising candidate for application in a targeted drug delivery system.