Live Biosensor
3D Printer printed Bacteria sticker-Chemical Sensor
Grigory Kopiev, Naked Science
Scientists have created a material from genetically modified bacteria that can print logic gates and whole chemical sensors, including those glued to the hand, according to an article published in the journal Advanced Materials (Liu et al., 3D Printing of Living Responsive Materials and Devices).
In this case, the material can be used to print sensors on a 3D printer.
In the last few years, 3D printing has been adapted not only to create structures made of plastic, metal and other materials, but also to create electronics, and not only simple conductive elements. For example, this method has been used to create stretch or compression sensors, as well as other sensors, while some researchers are even experimenting with bacterial-based materials.
Scientists led by Xuanhe Zhao from the Massachusetts Institute of Technology have developed a 3D printing material that allows the detection of specific substances with the help of bacteria. It is based on a hydrogel of several components: pluronics, which serves as the basis of the hydrogel matrix, a photoinitiator that binds the components of the hydrogel after ultraviolet irradiation, genetically modified bacteria Escherichia coli (E. coli), as well as a nutrient medium for them.
The sensor is a tattoo for detecting three substances.
Here and below are the drawings from the article in Advanced Materials.
The researchers modified E. coli so that it produces a green fluorescent protein in the presence of specific substances, and created modifications to detect three substances. They printed several simple three-dimensional designs on a 3D printer, as well as a sensor sticker. It is a "tree" printed on a thin biocompatible polymer substrate that easily adheres to the skin. The "tree" consists of three parts, each of which is sensitive to one specific substance. The researchers demonstrated that the sensor begins to fluoresce within a few tens of minutes after the addition of the signaling substance.
Logic gates based on new material.
In addition, scientists were able to create logic gates based on such material, which, performing a particular logical operation, convert input signals into output. To do this, they created, in addition to modifications of bacteria that produce fluorescent protein, also modifications that reduce its production and modifications that produce signaling substances. Due to this, as well as the special arrangement of fragments with certain bacteria, they received valves of the types NOT, AND, OR and NOT AND.
This is not the first time bacteria have been used as chemical sensors. In the spring of 2017, Israeli scientists successfully tested bacteria sensitive to trinitrotoluene as detectors of mines buried in the ground. They scattered beads with these bacteria on the "minefield", and were able to detect containers with mines at a distance of 20 meters. And other scientists have recently developed a 3D printing material that also contains bacteria, but in their work they used bacteria that decompose phenol and produce cellulose.
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