Science | ‘Frankenstein’ material can self-heal, reproduce
Life is at the heart of much of our material world. We make two-by-four beams from wood, ethanol from corn, and textiles from cotton. But bricks? Researchers have now created a form of concrete that not only comes from living creatures but—given the right inputs—can turn one brick into two, two into four, and four into eight. Although the new material won’t build self-assembling houses anytime soon, it could soon lead to building components that can heal themselves when damaged. The living concrete could even offer Mars-bound astronauts a way to build structures from local materials plus a few adventurous microbes.
The new concrete is the latest addition to the burgeoning field of engineered living materials (ELMs), in which organisms—typically bacteria—are added to inanimate materials to enable them to sense, communicate, and even respond to their environments. In recent years, researchers have created ELMs that sense pressure, kill dangerous bacteria, and sense light. But those materials are usually thin films grown atop structural supports.
For this project, Wil Srubar, a materials scientist at the University of Colorado, Boulder, and his colleagues wanted to engineer life into a bulk structural material. To do so, they turned to a hearty photosynthetic cyanobacterial species in the genus Synechococcus. They mixed the cyanobacterium with sand and a hydrogel that helped retain water and nutrients. The mix provided structural support to the bacteria, which—as they grew—lay down calcium carbonate, similar to the way some ocean creatures create shells. When dried, the resulting material was as strong as cement-based mortar. “It looks like a Frankenstein-type material,” Srubar says. “That’s exactly what we’re trying to create, something that stays alive.”