The olfactory (smell) receptors in living organisms are so sensitive they can detect smells that consist of one molecule. The natural smell receptors in our noses pick up compounds known as volatile organic compounds (VOCs). The artificial VOC sensors that have been available so far are far inferior to the natural olfactory receptors.
A Japanese team led mainly by University of Tokyo Professor Shoji Takeuchi has come up with a system using biohybrid sensors in which living olfactory sensors and co-sensors taken from the yellow fever mosquito (A. aegypti) are placed into a lipid bilayer between two droplets which is then integrated onto a chip with a gas flow system. The gas flow system introduces the VOCs into the droplets and transports them to the olfactory receptors, thereby achieving a very high level of detection sensitivity.
Octenol (1-octen-3-ol) is an odor molecule found in the breath and sweat and is a possible biomarker for cancer, being more prevalent in the breath of people who have contracted cancer. It can be cytotoxic to our cells and also cause neurodegeneration. Research2 has found three volatile compounds to be significantly (p<0.05) elevated in the blood of patients with liver cancer, with a sensitivity of 84.2% and specificity of 100% for octenol.
Mosquitoes are very sensitive to octenol, which is manufactured synthetically and used to attract mosquitoes in mosquito traps. Therefore using mosquito olfactory receptors can be a highly accurate manner in which to detect the presence of Octenol. Prof. Takeuchi’s team were able to show that their system prototype, which is the size of a lunchbox, was successfully able to detect octenol in human breath within ten minutes at a concentration of 0.5 parts per billion. The researchers have stated that the system can be created at low cost and can be produced and made available commercially within ten years.
- Tetsuya Y, Sugiura H, Mimura H, Kamiya K, Osaki T, Takeuchi S. Highly sensitive VOC detectors using insect olfactory receptors reconstituted into lipid bilayers. Science Advances 13 Jan 2021:Vol 7, no 3, eabd2013 https://advances.sciencemag.org/content/7/3/eabd2013
- Xue R, Dong L, Zhang S, Deng C, Liu T, Wang J, Shen X: Investigation of volatile biomarkers in liver cancer blood using solid‒phase microextraction and gas chromatography/mass spectrometry. Rapid Commun Mass Spectrom. 2008, 22 (8): 1181-1186. 10.1002/rcm.3466. https://pubmed.ncbi.nlm.nih.gov/18350562/