Fabrication of magnetic hollow silica nanospheres for bioapplications

Different kinds of nanospheres are used in magnetic nanosphere fabrication for bioapplications. In this paper, we report a successful synthesis of magnetic hollow silica nanospheres (MHSNS). The MHSNS were fabricated with a one step coating of Fe 3 O 4 magnetic nanoparticles (NPs) ( ∼ 10 nm ) and silica on nanosized ( 20 - 100 nm ) spherical calcium carbonate ( Ca C O 3 ) surface under alkaline conditions, in which the nanosized Ca C O 3 were used as nanotemplates and tetraethoxysilane and magnetic NPs were used as precursors. The as-synthesized nanoshperes were immersed in an acidic solution to remove nanosized Ca C O 3 , forming MHSNS. The MHSNS were characterized by SEM, TEM, and SQUID. SEM and TEM results showed that a smooth surface of MHSNS and a thin layer of silica ( ∼ 10 nm ) embedded with the magnetic NPs was successfully formed. No nanosized Ca C O 3 nanotemplates were observed. SQUID measurement demonstrated that magnetization of MHSNS was dependent on temperature, exhibiting superparamagnetism. The MHSNS have potential applications in biomedicine and bioseparation.