Abstract

The Continuous Droplet Interface Crossing Encapsulation (cDICE) is an easy and robust method for producing, at high yield, monodisperse lipid vesicles with a controlled content as well as capsules with a designed shell. We will discuss the physical mechanisms involved in the production of both cDICE vesicles and capsules, and several applications, such as the production of artificial red blood cell or biolarvicide capsules.

The set-up consists in a cylindrical rotating topped-chamber, filled with a Dispersing Aqueous Solution (DAS) and a lower density solution (LDS) that form a vertical interface due to the centrifugal force. Droplets of the aqueous solution to be encapsulated (EAS) are injected in the LDS by dripping. Centrifugation of these droplets leads to their crossing of the LDS /DAS interface either at low or high inertia depending on the rotation speed. Low inertia is the regime used to produce vesicles: during the droplets ‘flight’ across the LDS layer, a monolayer of lipids dispersed in the LDS adsorbs onto the aqueous droplets, which zip with the monolayer spontaneously formed at the LDS /DAS interface, leading to vesicles suspended in the DAS . For the design of original capsules, the droplets cross the interface at high inertia, thereby entraining some LDS , which will in fine constitute the shell of the capsules stabilized by liquid to solid temperature controlled transition or UV polymerization. The cDICE method allows to encapsulate various biological solutions (biopolymers, hemoglobin, colloids, polymeric gels, cells…) in membranes that can be composite and/or assymetric, or polymeric. Its key-steps will be discussed in terms of hydrodynamical and colloidal interactions.