Preparation of micron-scale monodisperse oil-in-water microspheres by microchannel emulsification

Micron-scale monodisperse oil-in-water (O/W) microspheres (MS) were prepared using a novel microchannel (MC emulsification technique. The characteristics of the MS preparation and the O/W-MS prepared were studied. Soybean oil and medium-chain triacylglycerol (MCT) were used as the dispersed phase, and physiological saline was used as the continuous phase, Silicon MC with 1 to 3 mum-equivalent channel diameters were employed. A novel MC module was devised to easily recover the O/W-MS prepared. The effects of the channel shape on the behavior of MS formation, on the MS size, and on the distribution were investigated. An MC with a terrace at the MC outlet stably yielded micron-scale monodisperse OM-MS; the MS had diameters of about 5 mum, and their coefficients of variation were below 9%. Monodisperse food-grade O/W-MS with diameters of about 4 mum could be obtained by using polyglycerol fatty acid ester as the surfactant. The size and size distribution of the recovered O/W-MS remained almost constant over 60 d, demonstrating their long-term stability.