New living materials are sprouting that don’t just sit pretty—they suck carbon from the air. At ETH Zurich, a multidisciplinary team has woven photosynthetic cyanobacteria into a printable gel, creating a “living material” that grows while actively sequestering CO₂.
The research, published in Nature Communications, details how the team stably embedded cyanobacteria into a hydrogel matrix. The polymer network was chosen to let light, CO₂, water and nutrients flow freely, so the microorganisms can spread evenly and thrive within the material.
“Such as the ability to bind CO₂ from the air by means of photosynthesis,” says Mark Tibbitt, Professor of Macromolecular Engineering at ETH Zurich.
Once printed, the gel structures only need sunlight and artificial seawater enriched with simple nutrients to kick off growth. As the cyanobacteria photosynthesize, they turn CO₂ and water into biomass, and, uniquely, they alter their surroundings to precipitate solid carbonates like lime.
“This is because the material can store carbon not only in biomass, but also in the form of minerals – a special property of these cyanobacteria,” Tibbitt explains.
Cyanobacteria have been master builders for more than two billion years. “Cyanobacteria are among the oldest life forms in the world. They are highly efficient at photosynthesis and can utilise even the weakest light to produce biomass from CO₂ and water,” says Yifan Cui, co–lead author of the study.
As the organisms pump out minerals, they reinforce the soft hydrogel from within. Over months, initially pliable structures slowly harden, thanks to mineral deposition that bolsters mechanical strength.
In lab tests, the living material captured carbon continuously for more than 400 days, binding around 26 milligrams of CO₂ per gram—mostly as mineral. That rate surpasses many biological approaches and rivals the chemical mineralisation seen in recycled concrete, which binds about 7 mg of CO₂ per gram.
To optimize performance, the researchers harnessed 3D printing to sculpt high–surface–area geometries that boost light penetration and promote nutrient flow by capillary action.
“In this way, we created structures that enable light penetration and passively distribute nutrient fluid throughout the body by capillary forces,” notes co–author Dalia Dranseike, whose designs kept cells productive for over a year.
Beyond the lab, architects are already experimenting with these biofabricated materials. At the Venice Architecture Biennale, ETH doctoral student Andrea Shin Ling scaled the process to room-sized installations. Her tree-trunk-like prints, standing as tall as three metres, can each bind up to 18 kg of CO₂ per year—about the same as a 20-year-old pine in temperate climates.
In Milan’s Triennale, another installation called Dafne’s Skin coats wooden shingles in living patina, turning decay into design and carbon capture. Both projects underscore how living façades might one day turn our built environment into a continuous carbon sink.
Looking ahead, Tibbitt envisions coating building exteriors with photosynthetic living materials that bind CO₂ throughout a structure’s lifespan. There are still challenges in scaling, durability and maintenance, but this study lays the groundwork for low-energy, eco-friendly carbon sequestration woven directly into the fabric of our cities.
The study has been published in Nature Communications.
