What do a tree, a printer and tissue structure for an implant have in common? Kind of a lot, if you ask Chunlin Xu, professor in renewable materials chemistry at Åbo Akademi University. He researches developing methods so that 3D prints made out of sustainable material alternatives from the forest might replace some animal and synthetic products in the pharmaceutical industry.
Let’s start from the beginning. The main constituents of wood are lignin, cellulose and hemicellulose. These substances can be extracted from wood chips that are left over from the paper industry, for example. Lignin can be likened to an adhesive and can be used, for example, when making bioplastics. Cellulose and hemicellulose can be used to purify water of heavy metals or organic pollutants, or as ingredients to make packaging materials stretchable. All of these areas are researched at Åbo Akademi University.
Chunlin Xu and his team have focused on another area where cellulose can be used, namely as a material for 3D printing. The idea of 3D printing is nothing new. The first research boom in this field happened about ten years ago, and in a few years, the use of 3D printers might be standardised in some industries such as pharmaceuticals. This is what Xu and his team focus on. Research has shown that nanocellulose can be used in the artificial tissue reconstruction, for example, for organs that can be transplanted.
Focus on sustainable materials for 3D printers
Xu and his team have developed several different applications that enable 3D printers to use cellulose as a print material. An example of this is three-dimensional printing of support structures for tissues based on biopolymers. These can be used in drug screening so that researchers can study how cells behave and interact and how they then become tissue.
Another example is the ability to print a type of hydrogel to treat wounds. These printouts physically look like the shape of the wounds and can be loaded with various medicines or growth factors that can promote and speed up the healing process. Another area where 3D printing with natural material alternatives may become popular is the cosmetics industry. Currently, this mainly pertains to the Asian market, where the demand for cosmetic implants is relatively high.
– There are many new areas where tissue technology can be used when you want custom objects. For example, many people have problems with teeth grinding, which causes their teeth to wear down. Imagine if you could just have your teeth scanned and the parts that needed to be repaired could be printed out, instead of the uncomfortable methods used today, where the patient has to bite together for several minutes to cast the jaw. Also in the medical field, there are several applications that are useful for visualising organs. Imagine that before surgery surgeons can print out what the organs look like, scan the human body and find solutions based on the printout. Or what cancer tissues look like, for example, says Chunlin Xu, who is a professor in renewable materials chemistry at Åbo Akademi University.
Benefits and challenges
So, what are the benefits of using nanocellulose instead of animal or synthetic materials, as has traditionally been done? There are several, says Xu.
– If you use tissue from animals in transplants, there is always a risk of transmitting diseases, something we can completely avoid by using pure natural materials. If we use 3D printing to develop medical support structures of natural biopolymers to stimulate the natural tissue, it opens up a completely different way of performing certain tests. In plain language, this means that animals do not have to be used to carry out a number of experiments. In addition, the method allows for individual models to be made with the materials. Nanocellulose is also renewable and completely biodegradable.
Another advantage is the cost: it is cheaper to use natural materials than materials from animals. For example, collagen, which is often used for elasticity in industries such as pharmaceuticals and cosmetics, largely consists of gelatine. It is really expensive because it needs to be processed and cleaned. Cellulose offers a good alternative that is also available in large quantities.
But of course there are also factors that slow down development. Xu sees two main challenges for the use of natural materials in the medical industry: the general scepticism about a new material, and the regulation of the market.
– A common perception is that materials that come from nature are animal food, not materials that are to be used to replace parts in human bodies. Convincing the industry of the benefits of natural materials, in this case cellulose, is a huge challenge. Then we also need to wrestle with the medical certifications and regulations in the European market, but fortunately there are forces here that are already working to drive development in the right direction. I personally see 3D printing as a tool that offers enormous possibilities. Natural materials are something of a gift from nature, and the fact that they are renewable offers a huge advantage over, for example, the synthetic polymers that we find in much of the plastic we use every day.
A third challenge is the financial side. Finland has enormous resources when it comes to forests and biomass. These assets will play an important role in the bioeconomy and circular economy of the future, so it would be important to increase the value of the products we can extract from the forest. The last piece of the puzzle in promoting research is funding.
– The key to all research success is funding and collaboration. I have been lucky enough to come to a small university where we can collaborate within the faculty, and we have also managed to find very good partners around the world. While our research at Åbo Akademi University includes developing three-dimensional support structures on which cells can then be grown, tailor-made solutions are needed, for example, for the 3D printer itself. Our partners at the University of Wollongong in Australia are good at this. We also collaborate with the University of Tampere, and are always looking for new partners who can further develop the research. Without cooperation, we will not get anywhere.
What will be the next step in your research?
– The next step is more collaboration with the end users and with the research partners in cell biology and pharmacy. We have good material, and I believe that we will have an even stronger supporting role in the work where our partners will have the opportunity to validate the various applications. Here, our most important task is to help them use our materials to then customise the material properties and identify in which contexts they do not work. Although we will probably never be able to completely replace the synthetic polymers, we can still find new uses where natural polymers can take over. This could lead the development in a positive direction in terms of nature, the environment and society.