Bacteria grows in water-based hydrogels in a similar wold to mold that appears on the top of a forgotten cup of coffee. However, with a more solid consistency than coffee, hydrogels provide microbes with a structure, allowing them to multiply into more complex, three-dimensional shapes.
Though the organisms would typically be unwelcome at any breakfast table, bacteria does secrete substances useful in a number of other applications. The so-called organic “microfactories” are in fact responsible for helping to heal wounds, and neutralize harmful chemicals.
The versatility of bacteria has earned it a place in 3D printing powered research. By using 3D bioprinters, scientists are discovering new ways of programming the organisms to make useful byproducts.
In one of the latest studies in this field, a team of researchers at ETH Zürich have developed their own proprietary “functional living ink,” nicknamed Flink, that theoretically can be tuned to produce almost anything.
Inside the microfactories
Flink is the latest product from a team led by André R. Studart. It is made from hyaluronic acid (common in epithelial, and neural tissues), long-chain sugar molecules, and pyrogenic silica, which acts as a thickener. To activate the Flink, and induce production of useful substances, bacterial microbes are added before printing.
In the case of the Studart group’s latest study, two types of bacteria are added; Pseudomonas putida and Acetobacter xylinum. The first bacteria is capable of breaking down phenol – a toxic chemical commonly used for industrial manufacturing. The second is capable of producing high-purity nanocellulose – a substance gaining popularity in wound care and as an additive in foods.
The benefits of bacteria
By adding the ability to work three-dimensionally with the bacteria, ETH Zürich researchers unlock further potential for the secreted substances. “Printing using bacteria-containing hydrogels has enormous potential,” explains Patrick Rühs, one of the study’s lead authors, “as there is such a wide range of useful bacteria out there.”
Deposition by a 3D bioprinter means that Flink can be directly written onto curved surfaces, and the skin. The nanocellulose producing ink could, for example, be used to 3D print therapeutic patches over burn wounds. In other cases, it may also be used to make an inexpensive, environmentally friendly sensors capable of confirming the purity of water.
Rühs continues, “Most people only associate bacteria with diseases, but we actually couldn’t survive without bacteria.” In addition, as yet there is no way of telling how long such a device might last, “As bacteria require very little in the way of resources,” says Rühs, “we assume they can survive in printed structures for a very long time.”
3D printing of bacteria into functional complex materials is co-authored by Manuel Schaffner, Patrick A. Rühs, Fergal Coulter, Samuel Kilcher and André R. Studart, and published online in Science Advances journal.
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Featured image shows ETH Zürich initials 3D printed using bacterial Flink. Photo via ETH Zürich