When bone wears out, is damaged or must be surgically removed due to disease, we can replace them with implants. How long the implant works depends a great deal on how well it grows together with the skeleton. After a few years, a new operation and a replacement are most often necessary. It is painful for the patient and expensive for healthcare.
“Metal implants in orthopedics usually have a life expectancy of around ten years, then they are encapsulated by soft tissue and the body rejects them. It is the body’s way of protecting itself from a material that it does not recognize,” says Wallenberg Academy Fellow Martin Andersson at the Chalmers University of Technology Department of Chemistry and Biotechnology.
The body’s own skeleton is a living material that is continuously reformed. Old bone cells are broken down, and new ones are built up. This is such a material that Martin Andersson wants to create in the lab.
“The idea is that the material shall have the same chemical composition and the same structure as our own bone. This way, it breaks down as quickly as the skeleton and is reformed so that, over time, a repair is achieved entirely without a joint,” says Martin Andersson.
But succeeding with this is a challenge.
A complicated material
Martin Andersson’s fields of research are nanomaterials and surface chemistry. He studies structures in nature and in the body and tries to create surfaces and materials inspired by them. Bone is made of structures on a nanometer scale - one nanometer is one billionth of a meter - and is defined as a nanomaterial.
“I have always been fascinated by how things work. At high school, I actually found physics and electronics to be easiest, and I never really understood chemistry. That’s exactly why I chose to study it at university. It may have been a strange reason, but in some way, I thought that I had to understand chemistry to understand other things,” says Martin Andersson.
Bone consists of calcium phosphate crystals that are up to 80 nanometers long and lie arranged like a string of pearls in soft networks of proteins.
“It is a difficult material to copy. Making the crystals is not so difficult, but placing them in a smart way in a string of pearls is complicated. Nanoparticles have a tendency to clump together, so how do we get millions of them to lay down in an orderly manner?”
Pores arrange the crystals properly
Martin Andersson and his colleagues work with a method where they use molecules of a kind that are called surfactants, with a water-soluble and a fat-soluble end. In a water solution, surfactants arrange themselves so that the water soluble ends point outwards and the fat soluble inwards towards other fat soluble ends. If this is done in high concentrations, a kind of gel is formed with a crystal-like structure. The gel hardens and becomes a material with pores where calcium phosphate crystals can grow. Thanks to the pores, the crystals obtain the right size and arrange themselves in the right way. Martin Andersson’s team is also testing other materials as frameworks.
“The crystals are always calcium phosphate. The other material must not be the same as the body’s, but it must have the same decomposition speed as the skeleton,” says Martin Andersson.
As early as a few years ago, he and a colleague succeeded in producing a kind of synthetic bone that can be placed on the surface of implants in order for the body to “recognize” the implant. Then it heals more quickly and more naturally. The technique has been patented and is sold in a company that Martin Andersson was involved in establishing.
“I think that it is really enjoyable to work with patenting and commercialization. It is also a creative process. You begin with an idea and it becomes a reality. But business is not always as logical as research: it is perhaps not the best product that wins. It can be frustrating, but educational.”
Collaboration provides access to new knowledge
In an earlier project, he was involved in developing a nanomaterial that would make surfaces self-cleaning from harmful substances, such as after chemical or biological warfare. Among the on-going projects, there is one that is about water purification using proteins, others involve studying whether nanoparticles might be toxic to the body.
He has spent the majority of his time as a researcher at Chalmers University of Technology, but he also spent two years at the University of Florida where he worked with cell membranes and biosensors. These were subjects he was completely unfamiliar with before.
“It was really interesting to apply what I knew to what they were doing. There is a point of working in the grey zone. You have a limited amount of time in life to acquire knowledge, so you have to work with others who have different knowledge!”
It is the creation process that drives him, being able to form ideas and test them. And learning new things - but only to a certain extent.
“I get bored a bit easily. When I have reached 80 percent of the knowledge, I’m not so interested in the last 20. Then, I prefer to jump to something else. It can be a disadvantage in certain contexts, but it can’t be helped. It should be fun, otherwise it won’t happen.”
Text: Lisa Kirsebom
Photo: Magnus Bergström