Encapsulation of hydrophobic or hydrophilic iron oxide nanoparticles into poly(lactic acid) micro/nanoparticles via adaptable emulsion setup

In this study, a one-step water-in-oil-in-water (W/O/W) emulsion process was employed to encapsulate either hydrophilic (similar to 10 nm) or hydrophobic (similar to 5 nm) iron oxide nanoparticles (IONPs) into poly(lactic acid) (PLA). Via the simple adjustment of emulsification temperature to high temperature (HT, 60 degrees C) or room temperature (RT, 25 degrees C), a transformation of PLA-IONPs composite particles from hollow microparticles to solid nanospheres can be achieved. At RT, PLA nanocomposite particles (30-200 nm) encapsulating IONPs were generated regardless of the hydrophobicity of IONPs. On the other hand, at HT, our method resulted in the hollow microparticles (2-5 mm). This study presents a fast and easily adaptable process to encapsulate either hydrophobic or hydrophilic IONPs into the hydrophobic polymeric particles, with different shapes and sizes, by simply adjusting the emulsification temperature through the one-step W/O/W emulsion. (C) 2016 Wiley Periodicals, Inc.