(Nanowerk Spotlight) Nature has perfected what human engineering still struggles to achieve: creating materials that can adapt, sense their environment, and transform harmful substances into useful ones. While modern materials science has produced remarkable synthetic materials, from superstrong alloys to smart polymers, these materials lack the dynamic capabilities of living systems that can respond to their surroundings and perform complex chemical transformations.
Scientists have attempted to bridge this gap by combining microorganisms with synthetic materials. Early efforts focused on embedding bacteria in soft materials like hydrogels, but these structures proved too fragile for practical use and often failed to provide the right conditions for bacteria to thrive. The ideal material would need both strength and the ability to sustain life – seemingly contradictory requirements that have stymied progress in this field.
A promising solution has emerged from researchers at ETH Zurich, who report in Advanced Materials (“Living Porous Ceramics for Bacteria-Regulated Gas Sensing and Carbon Capture”) their success in creating ceramic materials that serve as homes for living bacteria while maintaining structural strength. These materials can perform useful functions like removing carbon dioxide from air and detecting dangerous chemicals.
Living porous ceramic for carbon capture and gas sensing. The potential use of living ceramics as building materials is highlighted. a) The porous ceramic serves as a scaffold for the growth and activity of specific microorganisms. b) Carbon capture and c) gas-sensing capabilities are achieved by using wild-type photosynthetic cyanobacteria or engineered microorganisms designed as biosensors. (Image: Reprinted from DOI:10.1002/adma.202412555, CC BY)
The key to their success lies in the careful design of pore structures within the ceramic. The researchers used clay particles to create materials with two types of interconnected spaces: tiny pores less than 10 micrometers wide where bacteria can attach, and larger channels 50-1000 micrometers in size that transport water and nutrients. This dual-pore structure allows the ceramic to both house bacteria and supply them with what they need to survive.
The team demonstrated this technology’s potential through two applications. First, they filled the ceramic’s pores with photosynthetic cyanobacteria – microscopic organisms that naturally consume carbon dioxide through photosynthesis. When exposed to light, these bacteria-laden ceramics removed CO2 from air three times faster than bacteria in liquid culture, achieving a capture rate of 0.29 micromoles per square meter per second. The ceramic’s large surface area allows more bacteria to access light and CO2, enhancing their natural carbon-capturing ability.
For their second application, the researchers engineered E. coli bacteria to act as living sensors for formaldehyde, a common indoor air pollutant that can cause health problems at levels too low for humans to detect by smell. When these modified bacteria encounter formaldehyde, they produce an enzyme that generates a banana-like scent. This biological warning system can detect formaldehyde at concentrations of 0.12 parts per million – well below the one part per million threshold where humans can smell the toxic chemical directly.
The researchers solved several technical challenges to make these living ceramics practical. They designed the pore structure to pull water through the material using the same capillary action that draws water up through soil to plant roots. This passive transport system keeps bacteria alive without requiring pumps or external power. They also showed that the ceramics maintain strength comparable to conventional bricks and can be further reinforced using bacteria that naturally produce calcium carbonate – essentially creating bacterial cement.
The materials can be shaped using 3D printing, allowing complex structures that maximize surface area for bacterial growth and activity. This manufacturing flexibility, combined with the material’s strength and ability to sustain bacterial life, opens new possibilities for integrating biological functions into buildings and infrastructure.
These living ceramics demonstrate how combining biological and materials science can create new technologies that harness nature’s capabilities. By providing a durable home for bacteria while maintaining their ability to perform useful chemical transformations, these materials represent a step toward buildings that could actively clean air or warn of environmental hazards. The research also provides design principles for developing other materials that combine synthetic and biological elements, potentially expanding the toolkit for addressing environmental challenges.
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