Superparamagnetic high-magnetization composite spheres with highly aminated ordered mesoporous silica shell for biomedical applications.

Control of the morphology, mesostructure, and surface chemistry of multifunctional materials is important for their applications. We report here the fabrication of multifunctional spheres which possess a silica-coated magnetite core and a highly aminated mesoporous silica shell with radially aligned ordered pore channels. The well-designed core-shell structured spheres have superparamagnetism, high magnetization (32 emu g), large surface area (133 m g), uniform accessible mesopores (3.4 nm), and abundant amino groups on the mesoporous shell. Owing to the presence of the amino groups, the composite spheres exhibit high capacity for convenient connection of fluorescent dyes, which make them promising candidates for applications in various biomedical fields, such as cell imaging and cell sorting. Furthermore, a fibrin-specific magnetic resonance imaging (MRI) contrast agent was successfully prepared by connecting the composite spheres with pentapeptide Gly-Pro-Arg-Pro-Pro, which can significantly increase the MRI signal of thrombus.