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Graduate student Samuel Wilberforce and the Medical Materials Group are at the forefront of research into bone implants that could bring therapeutic benefits for years to come. For Samuel, studying at Cambridge is the latest in a personal journey that...

The Cambridge collegiate system broadens your horizons. As a graduate student at Girton, I find myself sitting at meals next to people who range from social scientists to zoologists

Samuel Wilberforce - graduate student

DeHigh up in a shiny glass building on the New Museums Site, materials scientist Samuel Wilberforce bends over a machine that makes small grey shapes, roughly the size of a teaspoon. He is working on the next generation of bone implant substitutes – biodegradable composites that will one day replace titanium, the alloy most commonly used to pin fractured bones.

The composites and structures that Samuel and his fellow researchers in the Medical Materials Group are developing offer significant advantages over conventional materials.

Metal pins and plates, inserted by a surgeon after a trauma, have to be removed once the bone has mended, requiring a second procedure along with attendant complications. Metal is also much stronger than bone and the healing section of bone becomes “lazy”, relying on the implant for support. In a phenomenon that scientists call “spoon feeding”, the mended bone loses its natural resilience.

New materials – based on plastics and ceramics – can be engineered to degrade at different rates and in different conditions, gradually dissolving into the body with no adverse effects. Materials of this kind are already used for drug delivery – for example in cancer treatments. To date, much of the research has focused on the biological and degradation properties of these materials rather than their load-bearing properties.

Samuel explains: “The trick is to come up with a material that has precisely the desired mechanical properties for a particular application. This might sound simple but, in reality, we’re talking about playing with a wide variety of load-bearing parameters in terms of strength, stiffness and flexibility to suit the conditions in the site of implantation.

“For example, a material used for finger implants has to be stiff and tough to resist deformation – at the same time as having the flexibility necessary for movement. A material used for high loading-bearing sites that have little movements, on the other hand, must be much stiffer.”

Thousands of hours

Samuel’s research involves up to five stages, each one requiring thousands of hours of meticulous testing and analysis. It demands a grasp of physics, chemistry, maths and biology – as well as an ability to use a wide range of specialist technologies – as he takes raw materials right through to prototype products in laboratory conditions.

First is the creation of the composite mix. Samuel is currently concentrating on polymers (such as poly-L-lactide) and calcium phosphate ceramics – but his techniques can be applied to other materials too. The polymer and ceramic must be blended in proportions that give the desired characteristics further along the manufacturing chain – a process that involves mixing the polymer and ceramic (by extrusion) and shaping and moulding it (by injection moulding) to obtain the desired shape.

After obtaining the desired shapes, the material is tested to investigate its compressive load-bearing properties at near physiological conditions, since compression is the main loading mode in the human body.

This research, and the skills Samuel has developed in carrying it out, are eminently transferable. It is likely that the materials he and his colleagues are developing will be used routinely by surgeons within the next ten to 15 years. Once he has completed his PhD, he plans to get a job in the medical materials industry as a research scientist or engineer. “I hope to spend my career taking this work forward and working closely with orthopaedic surgeons,” he says.

Samuel is notable not only for his ability to handle materials, work across a wide range of scientific fields and tabulate and analyse his results, but his own journey has taken him from a poor community in Ghana to a laboratory at the forefront of medical materials research, where he is part of a team of scientists from all over the world.

When Samuel was born in Tema, a small coastal city in Ghana, his mother was a single parent and still a teenager. She was extremely bright but had been unable to go to university. His arrival meant she had to focus her energy on providing an income – and she followed her own mother into the fish trade, buying crates of the day’s catch at the local harbour and selling them on to market traders.

It was unreliable work, meaning that some days the household had enough for money for three meals a day, sometimes just one. The family home was simple with just two rooms but Samuel’s mother and grandmother were determined that he should have a good education and they enrolled him into a private school, St Augustine’s College – one of the best in the area.

“Quite often there wasn’t enough money to pay the fees and I had to stay away from school. My grandmother, who was strict in the most loving way, taught me at home from books she’d collected. I read my friends’ textbooks when they came round to play and all the Hardy Boys stories. When I went back to school I was sometimes ahead of the class. The teachers were quite puzzled,” said Samuel.

25 applications

He got top marks in his final exams and went to university in Kumasi, in the Ashanti region of Ghana, to study Chemical Engineering – where again he was among the best students. Aware that the education he was getting was not up to par, Samuel began to spend hours online applying for scholarships at US universities. “I must have applied to at least 25 when I got an offer of a scholarship to study at an American university in Germany, International University Bremen,” he said.

Borrowing money for the airline ticket from an uncle, he flew to Germany with just 50 Euros in his pocket and not speaking a word of German. “It was tough at first as it was an intensive course – a four-year programme taught over three years – and the other students arrived knowing a lot more science than I did. But I survived and before long I was enjoying it.”

A good degree from International University Bremen won Samuel a place for further study in London, followed by a year in industry. He arrived in Cambridge two years ago to join the Medical Materials Group led by Professor Ruth Cameron and Professor Serena Best, which has many national and international collaborations with both academic and industrial partners.

“Living and working in Cambridge is really demanding and exciting as you’re working with people who are incredibly bright and motivated,” he says.

“On top of that, the Cambridge collegiate system broadens your horizons. As a graduate student at Girton, I find myself sitting at meals next to people who range from social scientists to zoologists – it’s a great chance to exchange ideas and get a glimpse of work going on across lots of difference disciplines. I love being part of such a diverse and interesting community.”

Sadly his grandmother, who on hot afternoons sat with him at the kitchen table as he learnt his times tables and practised his spelling, passed away a couple of years ago. However, she died in the knowledge that her grandson had been accepted by the University to take a PhD. “I know she felt proud – and that made me feel very happy,” he says.

“Working in a lab can be extremely tedious and frustrating at times. What keeps me going through the difficult times, and what drove me to aim high when I was a schoolboy in Ghana, is a desire to bring prosperity to my family combined with a need to be innovative and apply my abilities to the benefit of mankind.”