Engineering Living Materials: materials with new properties and functions
"Living materials" could contribute to future building materials with their ability to sense and react to environmental changes, capture CO2, or self-repair. The field is still in its infancy, but at the Dept. of Civil, Environmental, and Geomatic Engineering three research groups are exploring the potential of living materials. They combine living cells with conventional materials to develop living materials with innovative properties. An inside look at the ETH ALIVE initiative.
ETH ALIVE (Advance Engineering with Living Materials) brings together researchers from different disciplines to develop new materials for a wide range of applications. The spectrum ranges from medicine, biotechnology, and materials science to robotics, climate-relevant research, and materials development. In addition to building a state-of-the-art research infrastructure, a key goal of the initiative is to promote young scientists.
At D-BAUG, the research groups of Eleni Chatzi, Ueli Angst, and Ingo Burgert, together with their ALIVE fellows, are part of the interdisciplinary ETH initiative. The first ALIVE Symposium with external experts took place at the beginning of the autumn semester, where results of the first program phase (2021-24) were presented. In this context, D-BAUG News spoke to doctoral student Robert Kindler from the Chair of Wood Materials Science (ETH and Empa).
Robert, what exactly are living materials?
Living materials typically consist of two components: living organisms such as fungi or bacteria, which can be programmed to perform specific functions, and a carrier material that hosts these organisms. The organisms are utilized for their metabolic properties. For one thing, microorganisms can be more energy-efficient in producing complex substances; for another, different organisms can respond differently to external influences. We try to harness these functions to develop materials with unique properties that might go beyond the possibilities of conventional, non-living materials. Examples include the ability to self-heal in the event of damage and to detect or react to environmental influences.
But isn’t it easier to produce such new materials in industry?
In fact, when it comes to developing materials, a lot can be learned from nature. That’s why, in recent years, more and more researchers worldwide have begun investigating the potential of bacteria, algae, or fungi to act as “tiny factories” for the more sustainable production of complex materials. This refers to organisms being extremely efficient producers at ambient temperature and under normal pressure of complex materials such as bones, muscles, membranes, etc. In contrast, traditional manufacturing processes often need to work at very high temperatures, under high pressure, using solvents and the like.
What are the challenges of working with living materials?
The biggest challenge when working with living organisms is controlling and directing them so that they perform the intended processes consistently. That’s why we often have to optimize various conditions – like temperature, pH value, and nutrients – to ensure that the organisms behave as intended. Upscaling these processes is an additional challenge. While microorganisms are very efficient at producing materials in the micrometre range, it can be very difficult to keep these processes stable for larger dimensions.
Microfluidic chip: Designed to mimic the intricate structure of wood cells. Using such model systems helps to predict bacteria behavior for later applications. (Photo: D-BAUG, ETH Zurich / Pallavi Keshri)
What is your research about?
I combine organisms with wood and wood particles to produce more sustainable wood composites. In one of my projects, I’m focusing on using mineralizing bacteria to produce wood-mineral composites that make the wood more fire-resistant. In another project, I’m combining bacteria with wood samples to use the wood cells as a bioreactor. I aim to capture and store specific substances or convert them into another product. One area where this ability might prove helpful is in water treatment. Of course, before all this can happen, we must first develop a basic understanding of how bacteria interact with the wood.
What does your day-to-day work look like?
Most of my time is spent between the biology lab, fluorescence microscope, scanning electron microscope, and materials testing machines, thanks to the intensive collaboration with the research group of Prof. Andre Studart (D-MATL), as part of the ALIVE initiative. Working with living organisms requires a lot of planning and patience. They have their growth periods, so I have to plan my experiments carefully and ensure I hit the right growth phase to achieve the desired results. Then, we have to analyse the properties to see if these living materials can compete with conventional materials or perhaps replace them in the future.
Assuming that living materials become part of our lives, aren’t there also dangers?
That’s a very important question. Many people’s first reaction to materials that contain bacteria or fungi is to reject them. We need to communicate to the public about the actual risks and real benefits of such products. In my research, I use bacteria and fungi that are non-critical. However, a challenge for applications in this area is to avoid contaminating the materials with unwanted microorganisms that could potentially harm humans.
How did you end up working on living materials?
I studied chemistry as an undergrad, and while working on my Master’s thesis, I switched from pure chemistry to biochemistry and living cells. I was immediately taken by how efficient nature is at producing molecules inside living cells; in my studies, if I could do that at all, I’d have to employ advanced chemistry. I knew then that I wanted to learn more about the use and application of living organisms in material development.