3D printing with bacteria-loaded ink produces bone-like composites

Scientists from the Soft Materials Laboratory in the School of Engineering have developed a 3D printable ink that contains Sporosarcina pasteurii, a bacterium that triggers a mineralization process that produces calcium carbonate (CaCO3) when exposed to a urea-containing solution. The researchers call the ink BactoInk, and they can use it to 3D print virtually any shape that will gradually mineralize over a few days.

Nature can produce composite materials that are both light and strong, porous and rigid, such as mollusk shells or bone. However, producing such materials in a lab or factory using environmentally friendly materials and processes is challenging. The Soft Materials Laboratory researchers turned to nature to find a solution to this problem.

Inks that can be used for 3D printing must fulfill specific flow conditions, and the number of materials that can be 3D printed is limited. The researchers devised a simple trick: instead of printing minerals, they printed a polymeric scaffold using BactoInk, which is then mineralized in a second, separate step.

The mineralization process triggered by the bacteria in the scaffold leads to a final product with a mineral content of over 90%. The result is a strong and resilient bio-composite that can be produced using a standard 3D printer and natural materials without the extreme temperatures often required for manufacturing ceramics.

The Soft Materials Lab’s approach has several potential applications, from art and ecology to biomedicine. The method’s use of only environmentally friendly materials, and its ability to produce a mineralized biocomposite, also make it a promising candidate for building artificial corals, which can help regenerate damaged marine reefs.