Today I learned: that scientists have been trying to create artificial “noses”. Traditionally, dogs and other animals have been trained to identify specific smells like cancer, drugs, toxins, etc. But recent research is trying to design these artificial systems that could act as a way to screen for many odors at once. This groups of scientists used cells grown in the lab that have an olfactory receptor (OR) and proteins inside the cell that cause the cell to light up when an odorant (chemical that has a smell) is recognized by the OR. This works because in mammals, when an OR recognizes an odorant, that OR then becomes “activated” and transmits a signal into the cell. The cell then passes that message along to another cell, which passes it onto the area of the brain that processes these signals and tells us what we are smelling. They used seven odorants — ranging from those that smell like cloves to those that smell like banana — and tested them with many different ORs to see how much the cells lit up. With this they were able to identify specifically which ORs responded to which smells and how sensitively they could respond. This system can be used to help create systems that can discriminate between odorants, even if they look very similar in structure.
Reference: Kida, Hitoshi, et al. “Vapor Detection and Discrimination with a Panel of Odorant Receptors.” Nature Communications, vol. 9, no. 1, 2018, doi:10.1038/s41467-018-06806-w.