Nanoparticle-filled complex colloidosomes for tunable cargo release.

Capsules with a shell made out of nanoparticles, so-called colloidosomes, are very interesting for controlled encapsulation and release because of their selectively permeable shell, their mechanical stability, and the possibility to make them from many materials. Here, we report the creation of complex colloidosomes that can release encapsulated cargo on-demand in single or multiple release events. Unprecedented on-demand, multiple release is achieved by incorporating functional nanoparticles within the colloidosome hollow core. The entrapped nanoparticles enable pH-triggered release by either swelling to rupture the capsule shell in one single event or desorbing on-demand cargo molecules initially adsorbed on their surface. Implementation of such mechanisms in capsules with magnetically responsive shells enabled the creation of colloidosomes exhibiting unique spatiotemporal control of cargo release.