Our modern built environment is a carbon nightmare. Making cement, steel, and plastic—the materials we use commonly to build our infrastructure—emits large amounts of carbon dioxide.

Living building materials could shrink this carbon footprint. The intriguing idea involves embedding living cells in building materials so that they soak up carbon dioxide from the atmosphere. So far, researchers have made living brick-like materials by mixing sand, gelatin and bacteria; mixed bacteria into carbon-absorbing paint; and even self-healing concrete that uses an enzyme to capture carbon dioxide and produce minerals.

Now, a team from ETH Zurich has created a living material that can be 3D-printed into various forms. The gel material relies on photosynthetic bacteria that trap carbon dioxide from the atmosphere. The material then stores the carbon dioxide in biomass but also in the form of minerals, growing and hardening over time.

“As a building material, it could help to store [carbon dioxide] directly in buildings in the future,” said Mark Tibbitt, professor of macromolecular engineering, in a press release. Tibbitt and colleagues revealed their new photosynthetic living material in the journal Nature Communications.

The researchers use cyanobacteria, some of the oldest life forms in the world. The color of these photosynthetic bacteria gives them their informal name: blue-green algae. The bacteria absorb light and carbon dioxide to grow and to create solid calcium carbonate minerals.

The team dispersed these bacterial cells throughout a hydrogel, a water-rich gel made from polymers. The polymer network allows light, carbon dioxide, water, and nutrients to pass through.

Tibbitt and his colleagues 3D-printed various structures with the gel. They digitally designed structures that increase surface area, light exposure, and nutrient flow. This allows the cyanobacteria to stay alive and grow for over a year. The printed structures are soft to begin with, but as the bacteria grow and form carbonate minerals, the structures harden.

Laboratory tests showed that each gram of the material absorbs around 26 milligrams of carbon dioxide over a period of 400 days. As a practical demonstration, the team has also created an exhibit of two tree-trunk-like structures that can bind up to 18 kilograms of carbon dioxide per year, about the same as the annual carbon capture ability of a 20-year-old pine tree.

Source: Dalia Dranseike et al. Dual carbon sequestration with photosynthetic living materials. Nature Communications, 2025.

Image: Incubation chambers allow cyanobacteria to multiply in freshly printed structures. By Clayton Lee