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Bioelectronic ‘Nose’ Detects Spoilt Food by Sensing Decay Compound

Strong odors indicate that a certain food has gone bad; however soon there may be a new way to smell foul odors earlier on. Researchers have built a bioelectronic “nose” that can exactly detect a specific decay compound at low levels, enabling people to potentially do something about it before the smell spreads. It can identify rotting food, as well as be used to help locate victims of crimes or natural disasters. The details of the research can be found in ACS Nano.

When food starts to rot, the repulsive odor comes from a compound called as cadaverine. That is also the substance which causes the stench in rotting bodies, or cadavers — hence the name. The compound is formed due to a bacterial reaction involving lysine, which is an amino acid usually found in several food products. An earlier study has revealed that a receptor in zebrafish has an affinity for cadaverine. To create this receptor in the lab, the researchers chose E. coli as a host cell as it can easily create large quantities of proteins. But the production of this receptor in E. coli has been quite hard as it needs to be in a membrane. One way to achieve this is to form the protein in a bacterial cell and reconstitute it in nanodiscs, which are water friendly, membrane-like structures that the receptor can exist in in. So, Seunghun Hong, Tai Hyun Park and colleagues were keen to see if they could place the receptor into nanodiscs to build a sensitive and specific detector for cadaverine.

The researchers effectively created copies of the receptor in E coli and placed them into nanodiscs. The receptor-containing nanodiscs were then positioned in a special orientation on a carbon nanotube transistor, finishing the bioelectronic nose. During analysis with purified test compounds and real-world beef and salmon samples, the nose was sensitive and selective for cadaverine, even at low levels. Furthermore, the researchers say the detector could one day prove beneficial in finding bodies, since the compound is also created when a person dies.

The authors received funding from the National Research Foundation of Korea, the European Research Council, the BioNano Health-Guard Research Center and the Korea Basic Science Institute.

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