With this new technology, 3D printing comes to life… literally.

If humans are ever to live on Mars or the Moon, we will need to be able to construct buildings to live, sleep, eat and work in space. According to the space agencies, the way to achieve this is to 3D print habitats or their components. But transporting enough of the Earth-derived materials used for most 3D prints from our planet to another celestial body isn’t a feasible option.

Biology could solve this problem, says Neel Joshi, associate professor of chemistry and chemical biology at Northeastern. And Joshi’s team may have designed the technology for the job: a 3D-printable material that’s alive.

“As a tree has cells embedded within it and it grows from a seed to a tree by assimilating the resources of its environment in order to implement these structure building programs, what we want to do is the same thing, but where we provide these programs in the form of DNA which we writing and genetic engineering,” says Joshi.

Researchers have figured out how to program the bacteria Escherichia colialso known as E.coli, to produce a fully biological ink that can be used to 3D print solid structures. This microbial ink, which is described in a document published Tuesday in the journal Nature Communications, has yet to be tested on a cosmic scale, but scientists have used the gelatinous material to print small shapes, such as a circle, square and cone. They also successfully programmed it to build materials with specific attributes with other applications that could be useful in medicine.

Neel Joshi, associate professor of chemistry and chemical biology, works on programmable microbial ink for 3D printing of living materials, in the Mugar Life Sciences building. Photos by Matthew Modoono/Northeastern University

“We want to use living cells, microbes, as factories to make useful materials,” says Avinash Manjula-Basavanna, postdoctoral fellow in Joshi’s lab and co-lead author of the new paper. The idea, he says, is to exploit the properties specific to the materials that make up living beings for various purposes, ranging from therapy to industry.

“Think of it as a platform to build many different things, not just bricks for building or construction,” says Joshi. He explains the work by comparing it to how a polymer chemist considers how to design plastic materials that can serve distinct purposes. Some plastics are hard and hold their shape, while others are stretchy and soft.

“Biology is capable of doing similar things,” says Joshi. “Think of the difference between hair, which is flexible, and the horns of a deer or a rhinoceros or something like that. They are made of similar materials, but they have very different functions. Biology has figured out how to tune these mechanical properties using a limited set of building blocks.

The particular natural building block that scientists take advantage of is a protein produced by the bacteria E.coli. The material, called Curli fibers, is produced by bacterial cells when they attach to a surface and to each other to form a community. The same properties that make Curli fibers a sort of glue for bacteria also make it an attractive material for microbial engineers like Joshi and his colleagues.

The researchers 3D printed small shapes using microbial ink they developed from the bacteria Escherichia coli, also known as E. coli. Image courtesy of Duraj-Thatte et al., Nature Communications

To establish the microbial link, scientists started by growing genetically modified plants E.coli in a bottle. They fed the bacteria nutrients so that they multiplied, and as they divided they produced the desired polymers, the Curli fibers. Next, the researchers filtered the gelatinous polymers and fed this material into a 3D printing device as microbial ink.

Microbes have been used to make the ink for 3D printing before, but, according to Joshi and Manjula-Basavanna, what sets this microbial ink apart is that it’s not mixed with anything else. Their gel is completely organic.

A house made of a plastic-like material created by bacteria in Neel Joshi's lab.  Photo by Ruby Wallau/Northeastern University

One of the benefits of truly living material is that it is, in fact, alive, says Manjula-Basavanna. And that means it can do what living beings can do, like heal itself, like skin does. Under the right conditions, the cells in the microbial gel might just make more of themselves.

It’s not necessarily always growing, says Joshi. For example, if the cells were left alive in the little cone the team made from the microbial gel, “if you were to take that whole cone and dip it in a glucose solution, the cells would eat that glucose and they would make more”. of that fiber and grow the cone into something bigger,” he says. “There is the possibility of taking advantage of the fact that there are living cells there. But you can also just kill the cells and use them as an inert material.

While the initial gel is made entirely from genetically modified products E.coli, the researchers also tried to mix the ink with other genetically modified microbes in an effort to use the 3D printed materials for specific purposes. This is how they made a material capable of delivering an anti-cancer drug, which it released when it encountered a specific chemical stimulus. In another experiment, they also programmed another material to trap bisphenol A (BPA), a toxic chemical, when it encountered BPA in the environment.

“You might think of taking a bottle cap and printing our material inside it so that if there was any BPA around it would be sucked up through that and not be in your drink,” says Joshi.

This study was simply a proof-of-concept attempt, but Joshi sees this microbial ink as an open door to all sorts of possibilities for building things with biology.

“If there is a way to manufacture more sustainably, it will involve using living cells,” he says. “It’s moving more towards this kind of paradigm of building things with living cells.”

For media inquiriesplease contact Marirose Sartoretto at [email protected] or 617-373-5718.

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