Korea’s Electronic Nose has a Human Touch

Researchers from Seoul National University have combined their expertise in biotechnology and conducting polymer devices to produce a first-of-its-kind “bio-electronic nose” which they hope will significantly improve our understanding of the human sense of smell. By mounting human olfactory receptor proteins onto conducting polymer nanotubes, Korean researchers Tai Hyun Park and Jyongsik Jang were able to create a field-effect transistor which allows detection of electrical signal changes that occur when odor molecules bind to receptor proteins.

“The proteins have amine groups on the surface and the conducting polymers are functionalised with carboxylic acids, so we can covalently link the protein to the nanotube with a peptide bond,” explains Dr. Park. “This covalent attachment means that when the target molecule binds to the receptor, the signal is very effectively transferred to the nanotube.”

While the device has obvious applications in detecting specific molecules, Park explains that they want to use it to better understand how the human sense of smell works. “Around 370 to 380 different olfactory receptors exist, but many of them are not selective for single compounds and we don’t know what the targets of some of them are. We want to clone lots of different receptors and put them in devices like this, and then make devices with combinations of different receptors on, to try and detect more complex odors and understand how we distinguish them.”

“This is the first time I have seen conducting polymers used to immobilize receptors, and because they are covalently attached by amide bonds they are very stable” says Jasmina Vidic of France’s National Institute of Agricultural Research, who works on bio-electronic nose devices involving receptor proteins maintained within cell-membrane-like lipid bilayers. “The fact that they can selectively detect the target ligand means that the receptors are probably still in good shape (after being attached to the device), which is very promising.”