Soft microcapsules with highly plastic shells formed by interfacial polyelectrolyte–nanoparticle complexation

Abstract

Composite microcapsules have been aggressively pursued as designed chemical entities for biomedical and other applications. Common preparations rely on multi-step, time consuming processes. Here, we present a single-step approach to fabricate such microcapsules with shells composed of nanoparticle–polyelectrolyte and protein–polyelectrolyte complexes, and demonstrate control of the mechanical and release properties of these constructs. Interfacial polyelectrolyte–nanoparticle and polyelectrolyte–protein complexation across a water–oil droplet interface results in the formation of capsules with shell thicknesses of a few μm. Silica shell microcapsules exhibited a significant plastic response at small deformations, whereas lysozyme incorporated shells displayed a more elastic response. We exploit the plasticity of nanoparticle incorporated shells to produce microcapsules with high aspect ratio protrusions by micropipette aspiration.