March 2009 - Issue #5
On the surface it’s a love of engineering
Story by Eleanor Limprecht
View articles in related topics: Engineering, Health & Medical, Education
If it was not for a pottery subject in her final year of high school, Sally McArthur might never have become a biomedical engineer. While studying chemistry, physics, maths and art for her Victorian Certificate of Education (VCE) she became intrigued by the chemistry of ceramic glazes.
“I wanted to know why glazes had certain colours and how the elements came together. That led me to study materials engineering – using applied chemistry and physics to solve problems.”
It was not long before Sally – now Associate Professor McArthur after her recent appointment to Swinburne University of Technology’s Faculty of Engineering and Industrial Sciences – discovered a fascination for bioengineering, that is, engineering applied to medicine and biology.
With no bioengineering undergraduate degrees offered in Australia at the time, she instead completed an undergraduate degree in materials engineering at Monash University, then went on to do a Masters of Biomedical Engineering at the same institution.
Associate Professor McArthur describes herself as an engineer, but one whose focus involves biology or medicine.
“The most common applications people think of are rehabilitation engineering and biomechanics, but increasingly our work is about taking ideas from biology and using them to solve engineering problems,” she says.
For example, bioengineers studied mussels’ ability to stick to any surface to develop glues that work in wet environments; while by studying lotus leaves’ ability to float without becoming waterlogged, bioengineers developed super-hydrophobic surfaces.
Recreating natural effects synthetically – bio-mimicry – will be the focus of Associate Professor McArthur’s research at Swinburne.
She is using bio-mimicry to develop surfaces that mimic cell membranes. By growing cells on top of these surfaces and studying how the cells and the surfaces interact, she will have a more versatile way of looking at cell biology in a completely controlled environment.
“We can add in stimuli – say, an inflammatory response – and see how that changes the way the cell interacts with that surface. You’ve basically got a model system … you can think of it like Lego … where you can add elements in or take them out, but you can also control where the various different components move and what they interact with.”
For example, a synthetic cell membrane could be a new way to detect cancer cells in a complex mixture, such as a blood sample: “If we can create a surface on which the molecules move around and bind to particular molecules that are present on a cancer cell, and not a healthy cell, then you potentially have a way of detecting the cancer cell more easily,” Associate Professor McArthur says.
Eventually, she hopes her research could help improve understanding of the ways cells relay the biochemical information that facilitates tissue regeneration and growth, or conversely, the proliferation of cancer cells.
CSIRO researcher Dr Keith McLean, biomedical materials theme leader and former colleague of Associate Professor McArthur, says it is understanding such fundamentals that allows researchers to then engineer materials that have specific applications.
“Increasingly, we are looking at materials that influence biology. In the past, we wanted materials to be inert. Now we are increasingly looking at making materials smart; enabling them to interact,” Dr McLean says.
Although the focus of Associate Professor McArthur’s master’s degree was electrical engineering, she says there was a module on bio-materials taught by former CSIRO biomedical materials theme leader Professor Hans Griesser. During one of the lectures he said there was a position available for a technician. “I shot out of my seat, shouting ‘It’s mine! It’s mine!’,” she says.
Her enthusiasm and skills saw her appointed to the CSIRO position and she began working on a contact lens project with CIBA Vision. As an extension of this she was offered a PhD project at the University of New South Wales, which was working with CSIRO as part of the Cooperative Research Centre for Eye Research and Technology.
Together they were developing extended-wear contact lenses by making new materials that let oxygen through, since lack of oxygen leaves the eye vulnerable to infection.
Associate Professor McArthur says changes at the smallest scale – at a nanometre level – were required to develop surface chemistries that prevented proteins from adhering to the surface of the lens.
“We had to make the material more friendly for the human eye without changing the material’s engineering properties.”
Through the project, Associate Professor McArthur saw how a commercial research project came together, and her particular contribution was the increased understanding of how quickly proteins adhere to contact lenses.
After finishing her PhD, Associate Professor McArthur was appointed a senior research fellow at the University of Washington. Working in the bioengineering department, she looked at new ways of describing the chemical changes that occur on materials’ surfaces when they interact with proteins and other biomolecules and developed tools to explore these changes.
Part of the challenge was getting biomolecules to stay as close as possible to their natural organisation, even when researchers removed all water from the biomolecules’ environment.
Normally, when water is removed, a protein changes its shape, damaging its functional structure. To avoid this, researchers ended up using an idea from nature. In the desert, succulent plants have a sugar called trehalose, which binds to the same sites as water. This holds the protein’s structure, enabling succulent plants to survive longer without water.
“To mimic this process, we would adsorb a protein to the material we were interested in, then replace the water with a trehalose solution. The materials were then dried normally. Using this procedure we were able to show that it is possible to retain the structure and function of the protein on the surface in the absence of water,” Associate Professor McArthur says.
“We were the first people to apply this successfully in surface analysis techniques. Because we now had a way of maintaining a protein’s structure when the material was dry, we could start to use high-sensitivity chemical techniques to study the orientation of proteins on virtually any surface,” she says.
This type of insight is critical for biochemical and diagnostic assays of important molecules, including enzymes and antibodies.
From Washington, Associate Professor McArthur moved to the UK as a senior lecturer in biomedical engineering at the University of Sheffield. There she became involved in the development of microfluidic devices – tiny channels to move liquids around. Chemical reactions and assays performed in these allow new drugs to be developed sooner because chemical reactions occur faster due to the channels’ size. Because bioengineering was not as well recognised in the UK as it was in the US, Associate Professor McArthur also spent time introducing the subject to students.
This passion for teaching and inspiring the next generation was part of what made Swinburne appealing. “Teaching is the core business,” she says.
“I love that I can bring enthusiasm for my research to my teaching. It’s about how to get people to challenge and think matters through and problem-solve.”
Associate Professor McArthur believes that beyond a certain level of base knowledge, learning is enhanced by being able to see its relevance. “As academics, the earlier we introduce application-based ideas, problem-based learning, the better.”
