Uniform and stable hydrogel-filled liposome-analogous vesicles with a thin elastomer shell layer.

This study introduces a new type of uniform liposome-analogous vesicle with a highly stable shell structure in which water-in-oil-in-water double emulsion drops fabricated in a capillary-based microfluidic device are used as templates. The vesicles developed in this work consist of a poly(ethylene glycol) hydrogel core surrounded by a polyurethane (PU) film between 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) layers. Subjecting the double emulsion templates to UV irradiation leads to the formation of a PU elastomer film between the DPPC layers. The presence of a thin PU film sandwiched between the DPPC layers is confirmed by confocal laser microscopy. The thicknesses of the PU films are measured to be approximately ∼4µm. Further study reveals the incorporation of the PU film between the DPPC layers remarkably improves the shell impermeability. Our vesicle system is expected to be useful for regulating the permeation of small molecules through lipid-based vesicular films.

One-pot microfluidic fabrication of graphene oxide-patched hollow hydrogel microcapsules with remarkable shell impermeability.

Uniform hollow hydrogel microcapsules, composed of a graphene oxide platelet-patched shell, are fabricated in one step in a capillary-based microfluidic device. We demonstrate that patching a small amount of graphene oxide at the interfaces remarkably prevents the leakage of small molecules through the shell.

Microfluidic fabrication and permeation behaviors of uniform zwitterionic hydrogel microparticles and shells.

This study introduces a flexible and straightforward method for generating monodisperse complex hydrogel microparticles. For this, a water-in-oil emulsion was generated in a microcapillary device and then the emulsion drops were photo-polymerized to transfer them to hydrogel particles. The hydrogel microparticles were made of poly (2-methacryloyloxyethyl phosphorylcholine) that has an enhanced biocompatibility due to the phosphatidyl choline moiety in the backbone. The average mesh size of the hydrogel network, which is 50Å, was estimated on the basis of the Peppas-Merrill equation. This mesh size was experimentally confirmed again by NMR cryoporometry analysis and permeation test for dextran probes. Furthermore, to diversify the applicability of microfluidic technology, an oil-in-water-in-oil double emulsion was also fabricated by using the co-axial jetting of three combined flows in the micro-channel. Then the aqueous shell was polymerized to give rise to hollow-structured hydrogel microparticles. Finally, we have shown that the microfluidic approach is useful for fabrication of complex hydrogel microparticles that have potential uses in drug immobilization and delivery.