Multiwalled functional colloidosomes made small and in large quantities via bulk emulsification

Abstract

Colloidosomes are attractive microcarriers for encapsulation and controlled release. If their shell is composed of multiple layers of particles they are very robust against defects, which ensures a well-defined permeability. So far most capsules with multilayer particle shells could only be assembled using microfluidic emulsification, a technique that offers unparalleled encapsulation control but that is difficult to scale up for high material throughput. Here we propose a method that allows for high throughput assembly of multiwalled colloidosomes using double emulsion templates made in two simple bulk emulsification steps. Stabilization of the emulsion with interfacially adsorbed particles is key to enable control over the colloidosome architecture, which can display single or multiple internal compartments depending on the magnitude of the applied shear. In addition to the high throughput, our method also allows for the assembly of capsules with magnetically responsive shells and controllable release properties in a size range that has previously not been possible for multiwalled colloidosomes. The potential of such systems is illustrated by producing large quantities of multiwalled colloidosomes that are small enough to display Brownian motion in a fluid and that can be externally triggered to release molecular encapsulants on demand.