How living materials from algae can better capture carbon

Scientists from TU Delft have discovered how confined microalgae cells grow optimally in photosynthetic living materials. Through the use of light energy, microalgae convert CO₂ from the air into sugars, energy and oxygen for their survival. These living algae-based materials could be used in a range of applications, from functional objects to CO₂ capture, oxygen sources for biological tissues.

The team, led by Marie-Ève ​​​​Aubin-Tam and Kunal Masania, presented their new perspectives in Advanced materials.

“Engineered living materials (ELMs) constitute an exciting new class of materials that have the potential to revolutionize society,” explains biophysicist Aubin-Tam. “An example is photosynthetic living materials, in which organisms develop that actively carry out photosynthesis.”

In nature, many bacteria, algae and plants carry out photosynthesis; they absorb CO₂, water and light and produce sugars to survive. “We studied ELM with photosynthetic algae, which could ultimately be used to provide oxygen to biological or engineered tissues, where oxygen supply is often a growth-limiting factor.” Artificial engineering of biological tissues is particularly important given the growing need for organ transplants.

Control growth

“A main limitation that prevents the use of these materials on a larger scale is that we do not currently know how to control the growth of cells in these materials. This is what we have studied. We have studied how the growth of cells is affected by material shape, exposure to light, and access to nutrients and CO₂“, says Aubin-Tam.

“We were also able to show that the cells grew mainly along the edges of the material, where they have better access to air and light,” adds Jeong-Joo Oh, first author of the paper. Researchers found that a thin structure with a large surface area increases the efficiency of ELMs. In these, a relatively large part of the cells is located along the edges and therefore close to the air.

Nature has the answer

Interestingly, nature has come to the same conclusion, because the cell growth of elm corresponds to the structure of a plant’s leaf. The leaves have a thin structure with a large surface area to allow a large portion of the cells to be exposed to sunlight.

“In our results, we illustrate that accessibility to light and CO₂ This is the key. Introducing a small opening for gas exchange in the structures visibly improved cell growth in the inner layers. However, this comes at the cost of accelerated dehydration, which is ultimately not good for the cells,” explains materials scientist Masania.

This behavior is also analogous to nature. The leaves have very small holes, called stomata. “Like doors, leaves open their stomata to improve gas exchange while not letting too much water escape. Mechanisms that respond to a shortage of CO₂like the stomata of a leaf, would be very beneficial to photosynthetic ELMs and increase their longevity and efficiency in the future,” says Masania.

Interdisciplinary collaboration

In this research, the team studied different shapes of materials and their influence on cell growth. “To enable this, we needed to design a new composition of the ink, the material that comes out of the printer. We were looking for a new ink that would allow us to print larger and more complex objects,” explains Aubin-Tam. .

While his group at the Faculty of Applied Sciences was studying cell growth, Masania, from the Faculty of Aerospace Engineering, decided to contribute to the development of a new 3D printable ink. Together with Elvin Karana from the Faculty of Industrial Design Engineering, they explored the possibilities of producing 3D structures of living photosynthetic materials for future applications.

“The study of cell growth within ELMs is crucial for their efficient use and optimized functionality,” concludes Aubin-Tam. “We hope our work will motivate biologists, materials scientists, computer scientists and engineers to further research the cell growth and properties of this new class of materials.”