A team of researchers from the Delft University of Technology (TU Delft) has used a novel 3D bioprinting technique to create a living ‘artificial leaf’ material made of algae cells.
Living materials, which have seen increased use in research in recent years, are made by integrating living biological cells into non-living shells or matrices. The fabrication of such materials is often met with hurdles relating to mechanical robustness and functional performance, but the Delft team has managed to break new ground.
The research involved 3D printing microalgae directly into a non-living bacterial cellulose – an organic excretion compound produced by bacteria – to create a tough and flexible material capable of photosynthesis. With applications in circular fuel conversion and space-based oxygen production, the artificial leaf material is expected to pave the way for a more sustainable future.
“The printing of living cells is an attractive technology for the fabrication of engineered living materials,” explains Marie-Eve Aubin-Tam, an associate professor at TU Delft and co-author of the study. “Our photosynthetic living material has the unique advantage of being sufficiently mechanically robust for applications in real-life settings.”
Combining life and lifeless
Described by the scientists at printing ink onto a piece of paper, the living microalgae can be deposited onto the bacterial cellulose at millimeter-scale resolutions. Seeing as bacterial cellulose is flexible, tough, and strong in nature, the resulting material can be twisted and crushed without ever losing its original shape. As a bonus, it is also completely biodegradable and easy to produce at scale.
With the algae deposits inside, the material is capable of feeding itself over a period of several weeks via photosynthesis. The Delft team was also able to regenerate the material to grow larger samples on-site, using just the original culture. Even without any light source, the bioprinted material was found to survive stably for at least three days.
“We created a material that can produce energy simply by placing it into the light,” says Kui Yu, a Ph.D. student involved in the work. “The biodegradable nature of the material itself and the recyclable nature of microalgal cells make it a sustainable living material.”
What are the applications?
The team has cited artificial leaves as the primary application – materials that mimic real leaves by converting water and carbon dioxide into oxygen and energy. With the energy being stored in the algae in the form of sugar, it can be converted into usable fuel. As such, hard-to-reach environments such as the ISS or a colony on Mars can be supplied with both oxygen and energy without having to grow entire plants in biomes.
The technology can also be used to create sense-and-respond products here on Earth. These materials would be able to react to changes in the environment, providing heat insulation on cold days or water repellent properties in rainy conditions.
Elvin Karana, a co-author of the study, concludes, “What if our everyday products were alive: could sense, grow, adapt, and eventually die? This unique collaborative project shows that this question is beyond the realm of speculative design. We hope our article will spark new conversations between design and science communities and inspire new directions for investigations for future photosynthetic living materials.”
Further details of the study can be found in the paper titled ‘Bioprinting of Regenerative Photosynthetic Living Materials’. It is co-authored by Marie-Eve Aubin-Tam et al.
In a similar vein, scientists from Harvard Medical School have previously developed a novel algae-based bioink that can be used to 3D print soft tissue structures. The team formed their bioink by combining a photosynthetic algae and human liver cells into a hydrogel matrix, using the material to 3D print hexagonal structures featuring lifelike liver ‘lobules.’
Elsewhere, at the Dutch University of Wageningen, researchers have previously used 3D printing to develop microalgae-based cereal snacks. Using a dual-extrusion 3D printing process, the team attempted to make their healthy foods tastier and more visually appealing by customizing their shape, texture and color.
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Featured image shows TU Delft 3D bioprinted in algae. Photo via TU Delft.