Preparation of magnetic poly(lactic‐co‐glycolic acid) microspheres featuring monodispersity and controllable particle size using a microchannel device

Poly(lactic‐co‐glycolic acid) (PLGA) microspheres prepared using a traditional solvent evaporation or double emulsification method are usually polydisperse with an uncontrollable particle size distribution, which brings about poor application performance. In our research, monodisperse magnetic PLGA microspheres were prepared using a microchannel device based on a water‐in‐oil‐in‐water composite emulsion. The composite emulsion was formed by injecting a dichloromethane–gelatin water‐in‐oil emulsion into a microchannel together with an external water phase, i.e. poly(vinyl alcohol) (PVA) aqueous solution. Mean particle size control of the microspheres was executed using the osmotic pressure difference between internal and external aqueous phases caused by regulating NaCl concentration in PVA aqueous phase. It is found that monodisperse magnetic PLGA microspheres with high magnetic responsiveness can be successfully prepared combining the microchannel device with composite emulsion method. Mean particle size of the microspheres with coefficient of variation value below 4.72% is controllable from 123 to 203 µm depending on the osmotic pressure. The resulting samples have pyknotic and smooth surfaces, as well as spherical appearance. These monodisperse magnetic PLGA microspheres with good superparamagnetism and magnetic mobility have potential use as drug carriers for uniform release and magnetic targeting hyperthermia in biological fields. © 2015 Society of Chemical Industry