Cyanobacteria-Enabled 3D-Printed Material Converts CO2 into Highly Stable Minerals

What if the façades of tomorrow were not only to shelter residents, but also to clean the atmosphere? In Zurich, researchers have designed a material populated with cyanobacteria that trap CO₂ and convert it into minerals capable of remaining stable over the long term.

A hydrogel material housing cyanobacteria billions of years old

At a first glance, the material resembles a strange green paste emerging from a futuristic laboratory. Yet, its biological engine traces back to the origins of life. Cyanobacteria have existed for billions of years. They use light to absorb carbon dioxide and to produce the molecules necessary for their growth.

The ETH Zurich team embedded these microorganisms in a water-rich hydrogel. Its structure allows light, CO₂ and nutrients to pass through. This 3D-printed matrix can take on various shapes without suffocating the bacteria. The material is thus not limited to being biosourced. It remains biologically active and evolvable.

The carbon captured by cyanobacteria is transformed into solid minerals

Photosynthesis first enables the cyanobacteria to incorporate carbon into their biomass. But researchers observed a second mechanism even more surprising. The microorganisms alter their chemical environment and trigger the formation of solid carbonates, akin to those found in certain calcareous rocks.

This double capture drastically changes the outlook. Carbon stored in biomass can be released when cells die or degrade. By contrast, in mineral form it becomes much more stable. It integrates directly into the structure of the material, which gradually strengthens as if it were building its own skeleton.

The experiment lasted 400 days, an exceptional duration for a living system in a laboratory setting. At the end of this period, every gram of hydrogel had fixed about 26 milligrams of CO₂ in mineral form. Even as biological growth slows, the mineralization process continues to trap the carbon.

In Venice, these artificial trunks showed that architecture could capture CO₂

The research did not stay confined to sealed samples. During the Venice Architecture Biennale 2025, the Living Room collective unveiled large 3D-printed structures. They took the form of sculptural tree trunks, designed to expose the cyanobacteria to light.

In this controlled environment, one of these columns could absorb up to 18 kilograms of CO₂ per year, the equivalent of an adult pine. The result remains experimental, but it demonstrates the potential of a material capable of adapting at an architectural scale. Buildings could thus become players in the carbon cycle.

The most ambitious idea is to use this material as an exterior coating. A façade would then become a metabolic surface. It would gradually change its appearance, harden, and accumulate minerals over time. Architecture would no longer be static; it would interact with its environment.

Promising living façades, but constrained by biological limits

Several obstacles still hinder large-scale deployment. Cyanobacteria require constant water, light and nutrients. Temperature fluctuations, pollution or freezing can disrupt their activity. It is also necessary to assess the material’s overall impact, from its production to its maintenance.

The researchers are already exploring ways to improve its robustness. They adjust the hydrogel composition and tune the microorganisms. This approach does not replace emission reductions, but it could strengthen CO₂ capture strategies through a process powered by sunlight.

The most striking aspect, however, is the shift in perspective it imposes. For a long time, buildings were designed as passive structures. Tomorrow, some could grow, breathe and mineralize carbon. One question remains open: how far will we be willing to entrust living materials with the role of our cities?