[L’industrie c’est fou] 3D printable, this ink containing bacteria could repair coral reefs and works of art

The contributions of 3D printing are well established. In this context, researchers at the Soft Matter Laboratory of the Federal Polytechnic School of Lausanne (Switzerland) have developed an ink, intended for this technology and containing bacteria. It might make it possible to restore, in a more respectful and more efficient way for the environment, works of art, to build artificial corals to help damaged coral reefs to regenerate, or to find applications in the field of medicine. . When exposed to a solution containing urea, the bacteria Spore load of pasteuria used triggers a mineralization process that produces calcium carbonate. The shapes printed with this ink, nicknamed BactoInk, mineralize following regarding four days and become both very solid and light.

This invention responds to the problem of the flow of inks which must fulfill certain conditions, which limits the number of printable materials. “For example, they must behave like a solid at rest, while being extrudable by a 3D printing nozzle,” explains Esther Amstad, one of the authors of the study published in the journal Materials Today. She points out that inks containing small mineral particles have already been used to meet these criteria, but that the structures obtained tended to be soft or shrink on drying. This can lead to cracking and loss of control over the shape of the final product.

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A mineral content of more than 90%

“So we came up with a simple trick: instead of printing minerals, we printed a polymer scaffold using our BactoInk. […] After regarding four days, the mineralization process triggered by the bacteria in the scaffold leads to a final product with a mineral content of more than 90%”, assures Esther Amstad. The latter no longer contains live bacteria, since it was immersed in ethanol at the end of the process. “The versatility of the BactoInk process, combined with the low environmental impact and excellent mechanical properties of mineralized materials, opens up many new possibilities for fabricating lightweight, load-bearing composites that are more akin to natural materials than current synthetic composites,” sums up the scientist.

Another study published in 2021 led to the development of an ink entirely composed of genetically modified E. coli bacteria. The researchers wanted their bacteria to be able to shape materials as modular as plastic, stiff or soft depending on its composition, by harnessing a protein they naturally produce to attach to each other. Proof that these microorganisms can also be good.

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