Controllable in Situ Synthesis of Magnetite Coated Silica-Core Water-Dispersible Hybrid Nanomaterials

Magnetite nanoparticle coated silica (Fe3O4@SiO2) hybrid nanomaterials hold an important position in the fields of cell imaging and drug delivery. Here we report a large scale synthetic procedure that allows attachment of magnetite nanoparticles onto a silica surface in situ. Many different silica nanomaterials such as Stober silica nanospheres, mesoporous silica nanoparticles, and hollow silica nanotubes have been coated with a high density layer of water-dispersible magnetite nanoparticles. The size and attachment efficiency of the magnetite nanopartide can be well tuned by adjusting the precursor concentration and reflux time. The functionalization of Fe3O4@SiO2 nanoparticles with dye molecules and biocompatible polymers impart optical imaging modality and good colloidal stability in either buffer solution or serum. The functionalized materials also exhibited strong potential as negative contrast agents in T-2 weighted magnetic resonance imaging.