Fe2O3 nanoparticles as particulate emulsifier: Preparation of magnetic and biocompatible PLGA microcapsules

Magnetic iron oxide (Fe₂O₃, maghemite) nanoparticle-coated micrometer-sized poly(lactic-co-glycolic acid) (PLGA) microcapsules were fabricated via a combined system of “Pickering-type” emulsion route and solvent volatilization method in the absence of any molecular surfactants. Stable oil-in-water emulsions were prepared using Fe₂O₃ nanoparticles as a particulate emulsifier and a dichloromethane (CH₂Cl₂) solution of PLGA as an oil phase. The Fe₂O₃ nanoparticle-coated PLGA microcapsules were fabricated by the evaporation of CH₂Cl₂ from the emulsion, and then bare-PLGA microcapsules were prepared by the removal of the Fe₂O₃ nanoparticles using HCl aqueous solution. The two types of microcapsules were characterized in terms of size, component and morphology using scanning electronic microscope (SEM), Fourier-transform infrared, optical microscope, and so on. SEM with energy dispersive analysis system (EDS) study confirmed that, there is negligibly small amount of Fe₂O₃ in the bare-PLGA microcapsules after washing with HCl aqueous solution. Moreover, a possible mechanism for the formation of the microcapsules was proposed. The combined system of Pickering emulsion and solvent volatilization opens up a new route to fabricate a variety of microcapsules.