Massive, Generic, and Controlled Microencapsulation by Flow Focusing: Some Physicochemical Aspects and New Applications

Massive, nearly monodisperse, true microencapsulation of a wide variety of active ingredients within biocompatible shells can be achieved using flow focusing at moderate-high Reynolds numbers, a paradigmatic tool for highly controlled flow chemistry processes whose flexibility and physical aspects are briefly illustrated here. We show that the natural, regular capillary breakup of a laminar high-speed microjet produced by gentle mechanical means alone allows the production of true microcapsules with controlled dimensions. The process versatility is shown in a variety of examples including encapsulation of different materials as proteins and/or microorganisms in biocompatible polymers as poly-l-glutamic acid (PLGA). Microcapsules produced show nearly homogeneous size, well-centered core, and their size and structure are well predicted by simple theoretical models.