Recognizing that being able to enclose materials in capsules between 10 and 100 µm in diameter, while accurately controlling both the capsule structure and the core contents, is a key concern in life sciences work, scientists at the University of Cambridge (Cambridge, England) have developed a technique for manufacturing "smart" microcapsules in large quantities in one step—using tiny droplets of water. The release of the contents of the microcapsules can be highly controlled through the use of various stimuli. The capsules can be used as a substrate for surface-enhanced Raman spectroscopy (SERS), which enables the characterization and identification of molecules for applications such as medical diagnosis, forensic analysis, and environmental sensing.
Resulting from a collaboration between the research groups of Professor Chris Abell and Dr. Oren Scherman in the university's Department of Chemistry, the new technique uses copolymers, gold nanoparticles, and small barrel-shaped molecules called cucurbiturils (CBs) to form the microcapsules, thereby bringing the materials together at the oil-water interface.
"The technique provides several advantages over current methods, as all of the components for the microcapsules are added at once and assemble instantaneously at room temperature," says Jing Zhang, a Ph.D. student in Professor Abell's research group and lead author of the study. Various 'cargos' can be efficiently loaded simultaneously during the formation of the microcapsules; the dynamic supramolecular interactions allow control over the porosity of the capsules and the timed release of their contents using stimuli such as light, pH, and temperature, she says.
The Engineering and Physical Sciences Research Council (EPSRC), the European Union, and the European Research Council (ERC) funded the work. Its commercialization is supported by an ERC Proof of Concept grant, which was awarded to Scherman.
Full details of the work, which was published in Science, may be found at http://www.sciencemag.org/content/335/6069/690.abstract?sid=9105b02c-7822-4ed0-baa4-411f4e989070.