A team of researchers from the University of Massachusetts managed to develop a 'green' electronic detector with excellent performance
![Protein nanowires (greenish) derived from the bacterium Geobacter (background) are between electrodes (gold) creating a bioelectronic detector used to detect biomolecules (red). [Courtesy: UMass Amherst/Yao lab]](https://www.hayadan.org.il/images/content3/2020/05/Chemical-Sensor-Using-Organic-Nanowires-777x6221-1.jpg.webp)
More than thirty years ago, microbiologist Derek Lovley discovered the bacterium Geobacter in river mud. The bacteria grow protein threads in the form of hairs that are used as nanometer 'wires' whose purpose is to transfer charges to feed them and to communicate with other bacteria. The researchers explain that they developed this innovative detector in order to be able to measure ammonia concentrations since this gas is important in the fields of agriculture, the environment and biomedicine. For example, in humans, mouthwash containing ammonia may imply the existence of a disease, while in poultry farms, this gas must undergo close monitoring while controlling its concentrations for the benefit of the health of the birds and to prevent health imbalances and production losses. The researcher explains: "This detector makes it possible to perform sensing with great precision; It is much more efficient than existing electronic detectors. We did not expect these detectors to work so effectively. I really believe that these detectors will have particularly positive consequences for humanity." The researcher explains that existing electron detectors often have limited or low sensitivity, and are sensitive to the presence of other gases present in the test environment. In addition to the advantages of the new detector in the form of a more efficient function and low cost, "our detectors are biodegradable so that they do not create waste of electronic components and they themselves are sustainably produced by bacteria using renewable raw materials and without using toxic substances".
It was already known that the electrical conductivity of protein nanowires changes in response to the level of acidity - the level of acid or base - of a solution in which the protein nanowires are found. This fact prompted the researchers to examine the idea that these threads could effectively respond to binding to molecules and be used in the field of biosensing. "If you expose the threads to a chemical, their properties change and thus the reaction can be measured," explains the researcher. When the researchers exposed the wires to ammonia, "the response was really measurable and significant," the researcher adds. "Already at the beginning of the research we noticed that the detectors can be adjusted so that they can express the significant response. They are really sensitive to ammonia and to a lesser extent to other compounds, so the detector can be particularly selective." The nanowires are "very stable", according to the researchers, for a long time; The detector is consistently active and stable even after months of use, and it performs excellently. Says the lead researcher: "These protein nanowires always amaze me. This innovative use is completely different from any other field that has been used in the past. Earlier, the researchers used these nanowires to generate energy from moisture and use them as memristors (Wikipedia) for biological computing. However, the current use is innovative and unique.
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