It seems like scientists and innovators are able to 3-D print just about anything—bridges, schools and even prized cuts of Wagyu beef. Now, a team of researchers introduced a new printing material: an entirely living ink made of microbes, which they hope can be used to improve building materials, human health and the environment, reports Sabrina Imbler for the New York Times.
To make this microbial ink, scientists genetically engineered the bacteria E. coli to grow two types of protein polymers called curli nanofibers, according to a paper published last week in the journal Nature Communications. The shape of the proteins allow them to crosslink with each other, forming a mesh-like structure. The nanofibers were then filtered out of the E. coli cultures, leaving a gel-like material both viscous and elastic enough to be used as printing ink, reports Carissa Wong for New Scientist.
"In the same way that a seed has a set of genetic instructions to produce a tree, we want to provide biological cells with a set of genetic instructions that program them to make material structures with prescribed properties," co-author Neel Joshi, a chemist at Northeastern University, tells Neel V. Patel for the Daily Beast.
Scientists have created other living inks out of bacteria, but they added other materials—like acids, extracts and silica—to create a sturdier gel. This new ink has no other additions—everything comes from E. coli, the Times reports.
Once the ink was ready to test, the team printed four small objects: a grid, a box, a cone and a ring. Their experiment was successful: the ink flowed out of the printer's nozzle at the right consistency and solidified once it was printed. Plus, the gel was strong enough to stretch out between two pillars 16 millimeters apart without breaking, the Times reports.
"I remember that moment when it bridged this gap and I was screaming and jumping," co-author Avinash Manjula-Basavanna, a scientist studying living materials at Harvard at the time, tells New Scientist.
The team also found promising results when they experimented with combining the gel with other microbes programmed to complete certain tasks. In one case, they modified E. coli to produce azurin, an anti-cancer drug, when in contact with a chemical called IPTG. In another, they manipulated the E. coli to produce a material that can suck up BPA—a toxin often used to make plastics—from the environment, New Scientist reports.
Though the ink is in the very beginning stages of its development, researchers are hopeful about its future. They are currently trying to scale up the printable structures from the small shapes they have now to sturdier designs. If it works, the microbial ink could become a greener and more renewable construction material, ultimately leading to the possibility of self-healing buildings, per the Times. Plus, this research can be used to fashion new medical devices for cancer treatments or to clean up toxins in the environment.
"There is a lot of work to be done to make it scalable and economic," Sujit Datta, a chemical and biological engineer at Princeton University who was not involved with the research, tells the Times. "It’s hard to project into the future…but given the pace in this area, the future looks very bright."