Synthesis and characterization of silica-encapsulated iron oxide nanoparticles

The properties of magnetic core-shell nanoparticles greatly depend on their core sizes and shell materials. Silica shell can prevent the magnetic nanoparticles from corrosion and agglomeration. In addition, the hydrolyzed silica can provide silanol groups to facilitate surface biofunctionalization. In this paper, superparamagnetic Fe₃O₄ nanoparticles coated with SiO₂ shell were prepared by a one-pot water-in-oil microemulsion method. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM) were utilized to characterize the morphology and magnetic properties of the synthesized nanoparticles. The results indicated that by tuning the water/surfactant molar ratio (Wo) of the microemulsion system, core size of the resulting Fe₃O₄ nanoparticles can be altered. The size-controllable silica-encapsulated Fe ₃O₄ superparamagnetic nanoparticles have great potential to be applied as multifunctional tracer materials for magnetic particle imaging (MPI).