With live 3D printable material, Northeastern researchers bring space and medical applications to life.

Northeastern University researchers have created a 3D printable living substance that can self-grow and cure.

The proof-of-concept study aimed to leverage the unique qualities of the materials that make up living organisms for a variety of uses, including therapeutic and medicinal, industrial, and even space applications.

The scientists’ material is “really living” because it is wholly biological and not combined with anything else. It was created from genetically altered E. coli.

“Like a tree has cells embedded within it and grows from a seed to a tree by assimilating materials from its surrounds to perform these structure-building programs,” said Neel Joshi, Associate Professor of Chemistry and Chemical Biology at Northeastern University.

Living cells can be printed.

Researchers from the MIT Media Lab, Harvard University’s Wyss Institute, and the Dana-Farber Cancer Institute have previously employed genetically modified E. coli to create “alive” 3D printing materials.

The team’s Hybrid Living Material (HLM) manufacturing platform uses inkjet 3D printing, resins,

and chemical signals to activate reactions in biologically designed bacteria, with applications in the medical field.

Scientists have been experimenting with 3D printing living cells for bone-mimicking structures,

producing sensory neurons, and studying their mechanoresponsive behaviour in other parts of the world. These materials, however, contain living cells but are not termed “life” because they are mixed with numerous inert chemicals.

E. coli programming for 3D printing

Curli fibres,

which E. coli creates as

a natural building component,

adhere to a surface and to one another

to form a community,

which are produced by E. coli.

Curli fibres are intriguing to microbial engineers because they have the same qualities that make them a kind of glue for bacteria.

To make their living material, the researchers first devised a method of engineering the bacterium E. coli to produce a fully biological ink capable of 3D printing solid objects.

The researchers started by growing genetically modified E. coli in a flask and fed the bacteria nutrition

so that they could multiply and generate Curli fibre polymers

as they divided.

The gelatinous polymers were then filtered out, resulting in a

microbial ink that could be fed into a 3D printer.

While the use of microorganisms to create 3D printed inks is not new,

The fact that this microbial ink is 100 per cent biological and not combined with any other ingredients distinguishes it from others.

Examining the live matter

The Northeastern team printed miniature items in the shapes of a circle, square, and cone using the gelatinous material. The project’s goal is to employ the material’s live cells as “factories” to create materials

with certain properties,

such as those beneficial in medicine.

“Think of it as a platform for

building a variety of things,

not just bricks for structures or construction,”

Joshi said, comparing the team’s work to how polymer scientists create plastic materials for a variety of uses. “Biology is capable of similar feats. Consider the difference between flexible hair and horns on a deer, rhino, or other animals. They’re made of comparable materials, but their purposes are vastly different.
Because the material is “alive,” it may perform the same functions as living creatures, according to Manjula-Basavanna, a postdoctoral fellow in Joshi’s group. For example, the material can mend itself in the same way as the skin can, and under the appropriate conditions, the cells within the microbial gel might simply reproduce themselves. The substance, on the other hand, does not always increase.

“If you submerge [the] complete cone in a glucose solution, the cells will eat the glucose and produce more fibre, causing the cone to grow larger,” Joshi stated. “It’s possible to make use of the fact that there are living cells there.” However, you can simply destroy the cells and use the substance as an inert material.”

A World of Possibilities

While the initial gel is formed

completely of genetically modified E. coli,

the Northeastern researchers also tried mixing the ink with other genetically modified organisms

to develop various 3D printing materials.
The scientists used their trials to create a material that can deliver an anti-cancer medicine when it comes into contact with a specific chemical stimulus

, as well as a material that can trap the dangerous toxin Bisphenol A in its environment.

While the research is only a proof-of-concept,

Joshi believes the microbial ink might open up a world of possibilities for biologically-based construction.

For example,

the material could be used to build off-plane

t dwellings and their components,

as well as a variety of medical applications.
“It will involve employing living cells if there is a way to manufacture in a more sustainable manner,” Joshi added. “We’re getting closer to that type of paradigm of making things out of living cells.”