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.

Charge-driven interfacial gelation of cellulose nanofibrils across the water/oil interface

“…The structure of the interfacial layer, at this magnification, displays wrinkles and sharp cuts, caused by the disruptive sample preparation. The gel resembled a shell-like structure, similar to the microcapsule shells produced by polyelectrolyte-nanoparticle complexation reported by Kaufman et al 42 Homogeneous staining of the interfacial gel (shown in magenta, Fig. 5c) confirmed the presence of embedded oil.…”

Growth Mechanism of Polymer Membranes Obtained by H-Bonding Across Immiscible Liquid Interfaces

“…Complexation of polymers, surfactants or particles at immiscible liquid interfaces is an increasingly popular technique to produce all-liquid printable, reconfigurable and self-healing membranes, devices and capsules [1][2][3][4][5][6][7][8][9][10][11][12] . While layer-by-layer assembly of components at liquid interfaces enables to obtain good control over membrane thickness and composition [13][14][15] , an easier way to promote interfacial complexation is to dissolve the interacting species within two separate liquid phases, such as oil and water 6,[9][10][11][16][17][18][19][20][21] or two partially-miscible phases 2,5,[22][23][24] . As the components spontaneously diffuse towards the common interface, they selfassemble through non-covalent interactions such as electrostatic ones and form a membrane which grows over time up to micrometric thicknesses 10,11 .…”

On-chip polyelectrolyte coating onto magnetic droplets – towards continuous flow assembly of drug delivery capsules

“…water-soluble and oil-soluble PEs to form PE bilayers on waterin-oil droplets during their generation, later expanding the technique to form nanoparticle-PE/protein-PE complexes on the droplets. 24 Zhang et al 25 employed a similar technique using an aqueous two-phase system rather than immiscible fluids. However, while this one-step process is simple and fast for PE bilayer formation, the addition of more layers to form a full PMLC would be non-trivial due to the cumbersome construction of the capillary-in-capillary microfluidic devices.…”