Preparation of Uniform Microspheres and Microcapsules by Modified Emulsification Process

Abstract

AbstractSummary: Uniform microspheres and microcapsules have been prepared by developing a direct membrane emulsification technique from O/W, W/O and W/O/W emulsions in previous studies, and have been applied in bio‐separation and drug delivery systems. The diameter can be controlled from several microns to above 100 microns. However, smaller microsphere with submicron size, especially from W/O/W emulsion was difficult to be prepared. In this article, a modified emulsification technique was developed to overcome the problem. That is, a pre‐emulsion (W/O or W/O/W) with broad size distribution of droplets was prepared firstly by homogenization, sonification or mechanical stirring method, then the pre‐emulsion was pressed through the uniform pores of a Shirasu Porous Glass (SPG) membrane to obtain relatively uniform smaller droplets, finally the droplets were solidified to form uniform microsphere or microcapsule. Uniform chitosan microsphere and poly(lactic‐glycolic acid) (PLGA) microcapsule with submicron size were prepared from W/O and W/O/W emulsions, respectively. Further more, uniform polymer‐magnetite microcapsule was prepared by combining this technique and a new post‐precipitation process of magnetite.