Easy Route To Microcapsules

Researchers at the University of Cambridge have used supramolecular host-guest chemistry to fabricate cargo-carrying microcapsules from microfluidic droplets in a single step (Science, DOI: 10.1126/science.1215416). Oren A. Scherman, Chris Abell, and coworkers chose cucurbit[8]uril as the host molecule because it can form a ternary complex with two guests—in this case, methyl viologen attached to gold nanoparticles and a naphthol-containing copolymer. The researchers combined individual solutions of the three components in a microfluidic device to form a single aqueous phase. The oil phase shears droplets off the aqueous phase at a T junction. As the oil phase carries the droplets through a winding channel, the components combine to form hollow micro­capsules consisting of a dispersion of gold nanoparticles in a polymer mesh held together by cucurbit[8]uril. The size of the microcapsules ranges from 10 to 24 µm and varies with the ratio of the oil and aqueous flow rates. The researchers can load a variety of cargo—such as drugs, biological molecules, and even cells—in the microcapsules by adding a fourth solution to the aqueous phase during fabrication.