A Mild Method for Encapsulation of Citral in Monodispersed Alginate Microcapsules.

Citral is a typical UV-irritation and acid-sensitive active and here we develop a mild method for the encapsulation of citral in calcium alginate microcapsules, in which UV irritation or acetic acid is avoided. Monodispersed oil-in-water-in-oil (O/W/O) emulsions are generated in a capillary microfluidic device as precursors. The middle aqueous phase of O/W/O emulsions contains sodium alginate, calcium-ethylenediaminetetraacetic acid (EDTA-Ca) complex as the calcium source, and D-(+)-Gluconic acid δ-lactone (GDL) as the acidifier.

Controllable preparation of monodisperse alginate microcapsules with oil cores.

Here we report a novel strategy for controllable preparation monodisperse alginate microcapsules with oil cores, where the thickness of the alginate shells, as well as the number and diversity of the oil cores can be tailored precisely. Monodisperse oil-in-water-in-oil (O/W/O) emulsions are generated in a microfluidic device as templates, which contain alginate molecules and a water-soluble calcium complex in the middle aqueous phase. Alginate microcapsules are produced by gelling O/W/O emulsions in oil solution with acetic acid, where the pH decreasing will trigger the calcium ions being released from calcium complex and cross-linking with alginate molecules.

Trojan-Horse-Like Stimuli-Responsive Microcapsules.

Multicompartment microcapsules, with each compartment protected by a distinct stimuli-responsive shell for versatile controlled release, are highly desired for developing new-generation microcarriers. Although many multicompartmental microcapsules have been created, most cannot combine different release styles to achieve flexible programmed sequential release. Here, one-step template synthesis of controllable Trojan-horse-like stimuli-responsive microcapsules is reported with capsule-in-capsule structures from microfluidic quadruple emulsions for diverse programmed sequential release.

Monodisperse and fast-responsive poly(N-isopropylacrylamide) microgels with open-celled porous structure.

A simple and efficient method is developed to fabricate monodisperse and fast-responsive poly(N-isopropylacrylamide) (PNIPAM) microgels with open-celled porous structure. First, numerous fine oil droplets are fabricated by homogeneous emulsification method and are then evenly dispersed inside monodisperse PNIPAM microgels as porogens via the combination of microfluidic emulsification and UV-initiated polymerization methods. Subsequently, the embedded fine oil droplets inside the PNIPAM microgels are squeezed out upon stimuli-induced rapid volume shrinkage of the microgels; as a result, a spongelike open-celled porous structure is formed inside the PNIPAM microgels.

Simple and cheap microfluidic devices for the preparation of monodisperse emulsions.

Droplet microfluidics, which can generate monodisperse droplets or bubbles in unlimited numbers, at high speed and with complex structures, have been extensively investigated in chemical and biological fields. However, most current methods for fabricating microfluidic devices, such as glass etching, soft lithography in polydimethylsiloxane (PDMS) or assembly of glass capillaries, are usually either expensive or complicated. Here we report the fabrication of simple and cheap microfluidic devices based on patterned coverslips and microscope glass slides.

Novel cationic pH-responsive poly(N,N-dimethylaminoethyl methacrylate) microcapsules prepared by a microfluidic technique.

Novel monodisperse cationic pH-responsive microcapsules are successfully prepared using oil-in-water-in-oil double emulsions as templates by a microfluidic technique in this study. With the use of a double photo-initiation system and the adjustment of pH value of the monomer solution, cross-linked poly(N,N-dimethylaminoethyl methacrylate) (PDM) microcapsules with good sphericity and monodispersity can be effectively fabricated. The obtained microcapsule membranes swell at low pH due to the protonation of N(CH(3))(2) groups in the cross-linked PDM networks.