Olfactory receptor screening assay using nanovesicle-immobilized carbon nanotube transistor

Abstract

Olfactory receptor (OR) genes are considered to be the largest superfamily of the mammalian genome, and in the case of humans, approximately 390 kinds of functional ORs play a role in perceiving odors. In spite of their signifi cance in olfaction, the function of all ORs has not yet been fully revealed. In order to effi ciently identify specifi c ligands of orphan ORs, methods that can generate olfactory signals in a reliable manner and that can convert the cellular signals into measurable responses are required. Here, we describe an OR screening assay method using olfactory sensors that are based on cell-derived nanovesicles combined with single-walled carbon nanotube fi eld-effect transistors (SWNT-FETs). The nanovesicles contain ORs on their surface membrane and induce infl ux of calcium ions similar to olfactory signal transduction. This ion infl ux causes an electrical current change along the carbon nanotube, and then this change is measured by the SWNT-FET sensor. This technique facilitates the simple and rapid screening of OR functions.