Stephen Harris, 14 February 2012
Technology for more controlled drug delivery could be produced hundreds of times faster than with existing methods thanks to new research.
Scientists at Cambridge University have developed a faster process for manufacturing microcapsules — tiny spheres filled with drugs, pesticides or other substances — that also enables more precise control over when their contents are released.
The researchers have used microfluidics — where chemicals are combined in tiny sub-millimetre channels — to create droplets of a mixture that spontaneously assembles into capsules. These can then be broken down with light, heat or changes in pH.
‘Microfluidics has a very high frequency of generating those droplets and therefore capsules,’ PhD student Jing Zhang, lead author on the research, told The Engineer.
‘Currently I’ve only been doing a frequency of 300 to 3,000 droplets per second but it could go up to 100,000 droplets per second easily.’ Conventional methods produce around a couple of hundred microcapsules per second, she added.
Microcapsules are used to slowly release drugs inside the body, disperse pesticides over crops, add flavours or nutrients to food and even to release sealants in manufacturing processes.
The shell of the capsules either degrades over time or is broken down mechanically to release the contents. But the capsules produced through Cambridge’s method are more susceptible to other stimuli and so the release can be coordinated.
This could be particularly useful in manufacturing complex structures such as aircraft, where sealants usually need to be applied to parts one small area at a time to ensure a precise enough fit, said Zhang. ‘Potentially we could apply a signal and all the glue would be released in one go.’
The full report can be found in The Engineer.
Chemical and Engineering News
February 13, 2012 (p37)
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 cucurbituril 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 micro capsules consisting of a dispersion of gold nanoparticles in a polymer mesh held together by cucurbituril. 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.
Cambridge University Research News
11 February 2012
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. The findings are published Friday (10 February) in the journal Science.
The ability to enclose materials in capsules between 10 and 100 micrometres 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 full report can be found in Cambridge University Research News.
The Food Navigator
Nathan Gray, 10-Feb-2012
An innovative new technology platform could provide manufacturers and food formulators with greater control and speed when producing encapsulated ingredients such as flavours and bioactive ingredients, say its developers.
The new technology – a single-step method for producing ‘smart’ microcapsules using fluid droplets – is said to have potential commercial applications in food, nutrition, and pharmaceuticals, among others. Developed by researchers at the University of Cambridge, UK, and published in prestigious academic journal Science, the team behind the new technology promises that the ‘one-step’ microcapsules offer several advantages over currently used techniques.
Speaking with FoodNavigator.com, Dr Oren Scherman from the department of chemistry at Cambridge explained that the fluid technology used by the new platforms means that microcapsules have little variation in terms of size, and are “highly reproducible and scalable.” “I think that the fundamental advance that we have taken is the ability to both formulate the capsule and encapsulate cargo in a single step, so all the molecules and components are dynamically assembled simultaneously,” said Scherman, who was one of several researchers from the University of Cambridge involved in the platform’s development.
“We have on demand capability for release, and you can also have whatever you want as far as capsule size, or cargo, all in a uniform structure,” he said, noting that he was sure that there was “a lot of opportunity within the food manufacturing and production domain.”
“Because it’s a platform technology, it has a lot of applicability to many diverse areas, and I think that is something we are keen to explore through contact current leaders in the field,” added the expert.
The full report can be found in The Food Navigator.