Making polymers with light
A/Prof Cyrille Boyer
Cyrille Boyer uses light to make new and complex polymers.
It’s the latest in a series of techniques that have enabled him to create materials which are being applied in areas as widespread as non-stick coatings, anti-fouling technology, precision drug delivery, medical diagnosis and imaging.
His ideas are built on the revolutionary RAFT techniques for which David Solomon and Ezio Rizzardo received the 2011 Prime Minister’s Prize for Science. His latest technology uses light and chlorophyll to catalyse the creation of polymers using up to ten building blocks.
He’s using it to create nanoparticles that can carry drugs into the human body to break down bacterial biofilms associated with implants, cystic fibrosis, and sticky ear.
His patented technologies will herald a new era of smart polymers and eventually he believes he will be able to reconstruct complex polymers such as proteins and even DNA.
Cyrille is an Australian Research Council Future Fellow in the School of Chemical Engineering at the University of New South Wales.
For his contributions to polymer science, nanotechnology and nanomedicine Associate Professor Cyrille Boyer receives the 2015 Malcolm McIntosh Prize for Physical Scientist of the Year.
Cyrille Boyer’s citation in full
No-one could have predicted the reaction when Cyrille Boyer’s parents on their vineyard near Avignon, France made him a present of a chemistry set at the age of about 10. “I enjoyed playing with the chemical compounds, watching the changes in colour and other phenomena.”
The initial interest that kit generated has taken him all the way to becoming one of the most highly cited polymer chemists of his generation.
Cyrille Boyer likes his work to be practical. So when he arrived at the University of Montpellier (Ecole Nationale Superieure de Chimie de Montpellier) to do his PhD, he decided to focus on polymers. “Polymers are more than plastics. Almost everything in the biological world is made of polymers. We are made of polymers, such as DNA and proteins. And polymers or macromolecules play key roles in our life.”
But he did not start with natural polymers. His PhD was about developing adhesives to glue different layers of polymers together. These laminated polymers were to be used to manufacture petrol tanks which minimised vapour loss and reduced ozone air pollution. The layering allowed combinations of polymer characteristics, such as physical strength, resistance to petrol corrosion, and specific chemical properties. But polymers are difficult to glue together, and the development of the adhesives, themselves a form of polymer, demanded that Cyrille come up with new methods of polymer synthesis.
What he developed was an elaboration of the Reversible Addition-Fragmentation chain Transfer (RAFT) technique for which Australian Professors David Solomon and Ezio Rizzardo won the Prime Minister’s Science Prize in 2011. RAFT for the first time allowed control of the formation of polymers, long chains of individual identical molecules (monomers). It generated and made use of highly reactive free radicals to join and build the chains in a process that could be rapidly quenched at any time. It was one of Cyrille’s first brushes with Australian science.
But Cyrille wanted more control over his polymers than RAFT could provide. So, inspired by the work of Rizzardo and his CSIRO colleagues (Dr Graeme Moad and Dr San Thang), he developed a process in which the polymerisation was easily manipulated by light. He has since gone much further, inventing a linking process which can be activated and deactivated by light. This means you can determine where and when you introduce in the next link of the chain just by shining a light. In fact, using different wavelengths to control different kinds of links, you can use this technique to build complex polymer structures in three dimensions. Furthermore, this process allows you to use abundant and renewable green energy.
This light-activated technique has allowed Cyrille to build polymer chains out of not just one monomer, but up to ten different compounds. By doing so, you can introduce many different properties into the one polymer, achieving what he originally set out to do with his laminated polymers.
Now, he has gone even further, and has incorporated as a catalyst in the polymerisation process one of the world’s most common compounds, light-activated chlorophyll, the pigment plants use to manufacture sugars. This means we can now potentially use plants in a sustainable process to produce chlorophyll catalysts that induce polymerisation—and those catalysts will be entirely biodegradable
The applications of Cyrille’s work have already been significant. Initially, he applied what he had learned about building polymers for his adhesives in postdoctoral work with DuPont and the Tosoh Corporation of Japan producing novel forms of Teflon-like unreactive perfluoropolymers which are used in the aeronautics and aerospace industry. Not only are his techniques so precise that less energy is expended in making such polymers, but he has gone on to develop a new “green” manufacturing process for perfluoropolymers which eliminates the use of toxic surfactants.
It was at that point he was lured to Australia in 2006 to do a postdoctoral fellowship at UNSW. He has been here ever since. “I decided to move to Australia because the science is excellent, especially in polymers.” He has stayed because of the opportunities that have opened up for him and his opinion that “Australia is a wonderful country with lot of assets and outstanding potential”.
Now Cyrille is an Associate Professor in the School of Chemical Engineering, led by Prof Vicki Chen, in the faculty of Engineering at UNSW, an Australian Research Council Future Fellow, the Deputy Director of the Australian Centre for Nanomedicine, a member of the Centre for Advanced Macromolecular Design and an Australian citizen. “Australia has provided me with fantastic opportunities.”
His new techniques have allowed him to move into the world of nanotechnology and medicine, where he has developed new carriers of therapeutic agents, known as nanoparticles. Nanoparticles are conventionally made by combining chains of polymers which are hydrophilic (water-attractive) with chains of polymers that are hydrophobic (water-repellent). In the watery media of the biological world, these usually form little balls with hydrophobic hearts covered by a hydrophilic surface that carries the therapeutic compound.
Cyrille’s control of polymerisation is so good, however, that he can make polymer chains from both hydrophilic and hydrophobic monomers, and with water-attractive and water-repellent sections, they form nanoparticles. Nanoparticles formed in this way are much more sophisticated and highly-tuned for the job they have to do, and they allow the attached proteins to retain about 90 per cent of their normal activity.
What’s more Cyrille can now make the nanoparticles in different shapes—spherical, cylindrical, or just blobs (vesicles). And what he and his colleagues have found is that different shaped nanoparticles end up in different places inside cells, so the drugs they carry can be deposited with far more precision. His work in nanomedicine is performed in the Australian Centre for Nanomedicine led by Professors Justine Gooding and Maria Kavallaris, while his work in fundamental polymer synthesis is carried out in the Centre for Advanced Macromolecular Design led by Professors Per Zetterlund and Martina Stenzel.
One of the first applications of Cyrille’s nanoparticles has been as a carrier of nitric oxide for the treatment of biofilms. This technique was developed with a French microbiologist then in Australia, Dr Nicolas Barraud (now at the Institut Pasteur in Paris) and other colleagues, Professors Naresh Kumar, Thomas Davis and Scott Rice. Nitric oxide is used by cells for communication. Too much nitric oxide in the wrong place can disrupt communication.
So nitric oxide can be used, for instance, to disrupt the coordinated bacterial biofilms, which often form over surfaces. These bacterial biofilms are extremely difficult to treat due to their strong resistance against antibiotics. Nitric oxide can be used to clear the infectious bacterial biofilms which form on medical devices such as catheters, and are responsible for more than 100,000 deaths worldwide per year. Furthermore, biofilm infections, such as pneumonia in cystic fibrosis patients, chronic wounds and chronic otitis media, affect millions of people in the developed world each year and many deaths occur as a consequence.
But Cyrille’s nanoparticles can also carry all sorts of active biological macromolecules too—proteins, carbohydrates and nucleic acids, such as DNA and therapeutic agents (chemotherapy agents). Already, with Children’s Cancer Institute of Australia, in collaboration with Professors Maria Kavallaris, Phoebe Philips and Joshua McCarroll, Cyrille is working on a carrier of a nucleic acid compound which can be used to treat pancreatic cancer.
He has also incorporated magnetic iron oxide into his nanocarriers. This allows the nanoparticles to be guided into position by magnetism and then heated magnetically to release the drug or compound they are carrying. What’s more, the iron oxide acts as a contrast agent that is picked up by magnetic resonance imaging. So the whole process of treatment can be observed.
Natural macromolecules, Cyrille says, are very complex polymers with a perfect organisation. DNA is a chain of nucleic acids, for instance, and proteins of amino acids. Cellulose and starch are chains of sugars. Their perfection results from the exceptional information storage properties of DNA, while the sequence of amino acids confers the specific function of proteins.
|2006||PhD (Polymer Chemistry), University of Montpellier II, France|
|2002||Master in Materials Science, University of Montpellier II, France|
|2001||Bachelor of Chemistry, University of Montpellier II, France|
|2015 – 2017||High-end Foreign Expert, Chinese Government|
|2015||Organising committee, Australian Polymer Symposium and 5th International Nanomedicine Conference|
|2015||Co-organiser, “Advances in Polymers for Medicine” symposium, PacifiChem, Hawaii, USA|
|2015||Emerging Investigator, Polymer Chemistry (RSC publisher)|
|2014||Finalist, New South Innovations Innovation Award|
|2014||Organising committee, 4th International Nanomedicine Conference, Sydney|
|2013 – ongoing||Deputy Director, Australian Centre for NanoMedicine|
|2013||“Emerging Investigator”, Chemical Communication|
|2013||“Rising Star and Young Nanoarchitect in Materials Science”, Journal of Materials Science|
|2013||University of New South Wales (UNSW) Research Staff Excellence Award (Faculty of Engineering)|
|2013 – ongoing||Associate Professor, School of Chemical Engineering, UNSW|
|2012||Australian Research Council (ARC) Future Fellow, UNSW|
|2012||“Rising Star in Polymer Sciences”, Macromolecular Rapid Communication|
|2012||Scopus Young Researcher of the Year Award (Engineering and Technology)|
|2009||Australian Research Council (ARC) Australian Postdoctoral Fellow|
|2006 – 2009||Postdoctoral Researcher, UNSW|