Photographer:Fotograaf: Simone Golob
In a few years’ time you might find yourself sleeping under a blanket of sustainable plastic; plastic so refined and ‘natural’ it can be used to make textiles. Or perhaps your smartphone cover will be plastic made from sugar beets. At the Aachen-Maastricht Institute for Biobased Materials (AMIBM), research is underway on the development of sustainable materials for a cleaner world. The institute will be officially opened on Friday 9 December.
“Biomaterials are the key for innovation in medicine”
After working for eleven years as a cardiovascular surgeon, Prof. Stefan Jockenhövel*, scientific director at AMIBM, switched from the clinical environment to a more scientific one. “Not because I didn’t like my job. I just wanted to work on more novel solutions for medical applications.” In Jockenhövel’s own area, the cardiovascular system, surgeons perform heart valve replacements using mechanical heart valves made of carbon. A well-known alternative is a biological valve, made from strong yet flexible animal tissue, but they calcify and have to be replaced after roughly ten years. Heart valves made from patients’ cells open a high potential. But the available prostheses work for the right side of the heart. However, not for the left, due to the high blood pressure. “So we investigated natural biomaterials like fibrin, a protein involved in blood clotting, and combined it with a textile reinforcement, to see if we could develop a scaffold that is sufficiently resistant.” He created a hybrid implant where isolated cells from the human body were injected with a fibrin solution. He and his fellow researchers were the first in the world to perform this successful heart valve replacement in a preclinical animal study. “Biomaterials are the key for innovation in medicine. My colleagues are working on a project with chitosan, a natural, biodegradable polysaccharide obtained from the shells of shrimps. This chitosan has been shown to be an effective antimicrobial; it kills bacteria and is therefore very valuable for medical materials.”
* He is also director of the NRW Schwerpunktprofessur Biohybrid & Medical Textiels (BioTex) at the Institute for Applied Medical Engineering & Institut für Textiltechnik, RWTH Aachen University
Using stinging nettles in wound plasters
Ever heard of clothes made of fibres from stinging nettles? During the First World War there was a lack of cotton in Germany, and people made their clothes from this plant. Fortunately, the fibres do not irritate the skin. But when cotton could be acquired again this ecologically friendly fibre disappeared. Cotton was easier to harvest, after all.
Still, stinging nettle fibre could be having a resurgence, according to Postdoc Leonie Fritsch. She was trained as a biologist at the University of Bonn and obtained her PhD at the Fraunhofer Institute for Molecular Biology and Applied Ecology in Aachen. At Chemelot she is investigating how stinging nettles could be used in wound plasters. “The plant is known for its health benefits. It’s antibacterial and could be good to use in a purified way, as a layer on the wound plaster.” Fritsch is studying the plant’s metabolism, the entirety of its biochemical processes, to see how well it can be purified and whether just the cells, instead of the whole plant, can be processed.
This is not the only project she is working on. “I do several things and that makes it really nice. It’s multidisciplinary research. Sometimes we, the biologists, ask the chemists and physics what they can do with a certain material we found in a plant, and sometimes it’s the other way around.” Fritsch is looking at the metabolites of several plants – plants synthesise metabolites for defence – and what value they may have for applications in the food, pharmaceutical, chemical and cosmetic industries. “A plant has so many properties you can work with.” Consider the fibre of a hemp plant, one of the most valuable parts of the plant. “I read that these fibres are even used for car doors, as an alternative to plastic.” In Fritsch’s view, the search for alternative materials is a necessary one. “There are so many products in the world based on fossil oil. But what if that runs out?”
Improved and sustainable materials
Spider silk, DNA and starch: what do they have in common? They are all natural polymers, or large molecules made of repeated subunits called monomers. Their various properties make them ideal for use in everyday materials such as wool, natural rubber and cellulose. More well-known, however, are the man-made synthetic polymers that are used to make plastic, nylon, silicone, Teflon and more.
But what if you could put the molecular characteristics of one polymer into another? What if you could improve the materials and make them more sustainable? These are some of the questions that occupy Sanjay Rastogi, professor of Polymer Physics in the Biobased Materials research group. He studies the behaviour of polymers during the crystallisation process, either by means of a synthesis – combining two entities to form something new – or under the defined conditions of creating a product. “With this process you can modify the characteristics of the materials or even make your own molecular architecture. By changing the processing conditions, you can influence the melting point and properties like stiffness and strength. We want to introduce what was successful in one polymer into another. The unique features of the original are then combined with new features.” This way, a polymer can be used for different applications or a synthetic polymer can be replaced by a natural one. “The challenge is to really understand the specifics of polymers from their birth during polymerisation to their use in product development.”
Rastogi and his group have worked, for instance, on a simple polymer used to make plastic bags. “We increased its stiffness, made it easy to process and used environmentally friendly techniques to make bulletproof vests out of it. In another application we used it to make pipes for transporting water, oil or gas. They are as light as aluminium pipes but stronger, and will last longer without becoming corroded.”
The group is also involved in developing medical implants from monomers – the building blocks of polymers – that can be obtained from natural resources. “Ideally you use a biobased polymer, manufacture and process it using sustainable techniques, and make a product that not only meets the requirements of the market but is better than the existing product. That way you create added value.”
Wendy Degens and Cleo Freriks
Plastic is everywhere, but it is an unnatural product; made from fossil oil, not sustainable and not easy to recycle. High time for a new approach, according to the researchers of the Aachen-Maastricht Institute for Biobased Materials (AMIBM) on the Chemelot campus in Geleen. They are working on biobased materials – materials made fully or partly from biological components – in an effort to develop sustainable and innovative alternatives for technical and medical applications. Between more than fifty employees, from support staff to student assistants and professors, the entire ‘chain’ is being studied, from source (often vegetable) to chemistry to application. Plastic made out of sugar beet, to name just one example.
The AMIBM research institute is a partnership between Maastricht University, RWTH Aachen University (Institute for Textile Technology and Institute for Applied Medical Engineering) and the Fraunhofer Institute for Molecular Biology and Applied Ecology (Germany).
A two-year, English-language master’s programme in Biobased Materials has already been launched. The institute is partly funded by the Province of Limburg through the Kennis-As investment programme.