Monodisperse Fe₃O₄/SiO₂ and Fe₃O₄/SiO₂/PPy Core-Shell Composite Nanospheres for IBU Loading and Release.

The magnetic targeting drug delivery system is an effective way of targeting therapy. In this study, the monodisperse Fe₃O₄ nanoparticles with a particles size of about 180 nm were first prepared via a solvothermal method. Subsequently, the core-shell structure Fe₃O₄/SiO₂ and Fe₃O₄/SiO₂/polypyrrole (PPy) composite nanospheres were successfully synthesized by coating Fe₃O₄ nanoparticles with SiO₂ shell layer using the Stöber method and PPy shell by solvothermal method in turn. The as-prepared nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), and Ultraviolet-Visible spectrophotometer (UV-Vis). The results indicated that the as-prepared composite nanospheres displayed a well-defined core-shell structure and monodispersity. The thicknesses of SiO₂ shell and PPy shell were ~6 nm and ~19 nm, respectively. Additionally, the as-prepared nanoparticles exhibited high saturation magnetization of 104 emu/g, 77 emu/g, and 24 emu/g, and have great potential applications in drug delivery. The drug loading and drug release of the Fe₃O₄/SiO₂ and Fe₃O₄/SiO₂/PPy composite nanospheres to ibuprofen (IBU) under stirring and ultrasonication were investigated. Their drug loading efficiency and drug release efficiency under ultrasonication were all higher than 33% and 90%, respectively. The drug release analyses showed sustained release of IBU from nanospheres and followed the Korsmeyer-Peppas model.