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.