A new, single-step method of fabricating microcapsules, which have potential commercial applications in industries including medicine, agriculture and diagnostics, has been developed by researchers at the University of Cambridge, U.K. |
The
ability to enclose materials in capsules between 10 and 100 ?m
in diameter, while accurately controlling both the capsule structure
and the core contents, is a key concern in biology, chemistry,
nanotechnology and materials science.
Currently,
producing microcapsules is labour-intensive and difficult to scale up
without sacrificing functionality and efficiency. Microcapsules are
often made using a mould covered with layers of polymers, similar to
papier-mâché. The challenge with this method is dissolving the mould
while keeping the polymers intact.
Now,
a collaboration between the research groups of Professor Chris Abell
and Dr Oren Scherman in the Department of Chemistry has developed a new
technique for manufacturing ‘smart’ microcapsules in large quantities in
a single step, using tiny droplets of water. Additionally, the release
of the contents of the microcapsules can be highly controlled through
the use of various stimuli.
The
microdroplets, dispersed in oil, are used as templates for building
supramolecular assemblies, which form highly uniform microcapsules with
porous shells.
The
technique uses copolymers, gold nanoparticles and small barrel-shaped
molecules called cucurbiturils (CBs), to form the microcapsules. The CBs
act as miniature ‘handcuffs’, bringing the materials together at the
oil-water interface.
“This
method provides several advantages over current methods as all of the
components for the microcapsules are added at once and assemble
instantaneously at room temperature,” said lead author Jing Zhang, a PhD
student in Professor Abell’s research group. “A variety of ‘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.”
The
capsules can also be used as a substrate for surface-enhanced Raman
spectroscopy (SERS), an ultra-sensitive, non-destructive spectroscopic
technique that enables the characterisation and identification of
molecules for a wide variety of applications, including environmental
sensing, forensic analysis and medical diagnosis.
This
research has been funded by the Engineering and Physical Sciences
Research Council (EPSRC), the European Union and the European Research
Council (ERC). The commercialisation of this research is supported by an
ERC Proof of Concept grant, awarded to Scherman.
