Algae printed into tough material with plant-like properties

The scientists combined 3D printing with a novel bioprinting technique to print algae into living, photosynthetic materials which are also tough and resilient.

“Three-dimensional printing is a powerful technology for fabrication of living functional materials that have a huge potential in a wide range of environmental and human-based applications,” said Dr Srikkanth Balasubramanian, a researcher at Delft and first author of the study. “We provide the first example of an engineered photosynthetic material that is physically robust enough to be deployed in real-life applications.”

Srikkanth Balasubramanian and his colleagues started with a non-living bacterial cellulose: an organic compound produced and excreted by bacteria. Its combination of mechanical properties renders it flexible, tough, strong and able to retain its shape under physical distortions.

The bacterial cellulose is analogous to the paper in a printer, while living algae are analogous to the ink. Combining the living algae with non-living cellulose resulted in a unique material with the photosynthetic quality of the algae and the robustness of the cellulose. It is tough and resilient, as well as eco-friendly, biodegradable and simple and scalable to produce. Its plant-like nature means it can “feed” itself over many weeks through photosynthesis and it can be regenerated; a small sample of the material can be grown on-site to produce more materials.

The material’s characteristics made it a suitable candidate for a wide variety of applications in energy, medicine, fashion and space technology. The researchers suggested that it could be used to develop artificial leaves, photosynthetic surfaces or photosynthetic garments.

Artificial leaves use sunlight to convert water and carbon dioxide into oxygen and energy, as leaves do via photosynthesis. The leaves store energy in the form of sugars, which can then be converted into fuel; this renders artificial leaves a possible means of producing sustainable energy in places where plants struggle to grow, such as in space. Unlike most artificial leaves in production, the material produced by the Rochester and Delft researchers does not require toxic chemicals for production.

“For artificial leaves, our materials are like taking the 'best parts' of plants – the leaves – which can create sustainable energy, without needing to use resources to produce parts of plants that need resources but don’t produce energy,” said Professor Anne Meyer, a biologist at the University of Rochester. “We are making a material that is only focused on the sustainable production of energy.”

Photosynthetic skins could be used for skin grafts which aid healing through oxygen generation, while bio-garments made from this sustainable material could address some of the devastating environmental impacts of the textile industry. Clothing made from the material would remove carbon dioxide from the air; would not need to be washed as often as conventional garments, and would be fully biodegradable.

“Our living materials are promising because they can survive for several days with no water or nutrients access and the material itself can be used as a seed to grow new living materials,” said Professor Marie-Eve Aubin-Tam, a bionanoscience expert at Delft. “This opens the door to applications in remote areas, even in space, where the materials can be seeded on site.”