Research Progress in Synthesis of Nano-Microcapsules with Microfluidic Technology

Nano-microcapsules are widely used in biology, medicine, food, cosmetics and other fields. Compared with the traditional techniques for preparing nano-microcapsules, microfluidic can generate monodisperse single and multiple emulsion droplets, and control the size and structure of these droplets accurately. It is an ideal method to synthesize the nano-microcapsules with the properties of uniform size, controllable structure and controlled release. The review start with the structure types of microfluidic chips, such as co-flow, flow-focusing, T-juction, Y-shaped and their combination. And then the controllable microfluidic fabrication of single droplet, double droplets and multiple droplet templates and the solidification methods of droplets are summarized. Finally, the controlled release of nano-microcapsules preparing by flow microfluidics is also mainly introduced, it is divided into two parts: sustained release (controlled by particle size, surface morphology and shape, etc) and stimuli-responsive release (controlled by external environment such as pH, temperature, light and ion, etc).