Screening of target-specific olfactory receptor and development of olfactory biosensor for the assessment of fungal contamination in grain

• A bioelectronic nose that detects an indicator of fungal contamination in grain was developed.
• A specific olfactory receptor reacting to the indicator was determined.
• The sensor detected the indicator with high sensitivity and selectivity.
• The sensor can be used for the detection of fungal contamination in grain at an early stage.

We herein report an integrated olfactory system to carbon nanotube platforms for biosensing applications. In particular, this system can be used for the real-time monitoring of fungal contamination in grain through detecting 1-octen-3-ol, which is specifically generated from contaminated grain. A specific human olfactory receptor (OR) that recognizes 1-octen-3-ol was found using a cyclic adenosine monophosphate (cAMP) response element (CRE)-reporter gene assay. Then, OR-containing nanovesicles were produced from human embryonic kidney (HEK)-293 cells. The nanovesicles, which generate olfactory signals using endogenous cellular components and over-expressed ORs, were integrated into single-walled carbon nanotubes field-effect transistors (SWNT-FETs). The nanovesicles and SWNT-FETs play roles in perceiving specific odorants, and in amplifying cellular signals, respectively. Thus, the nanovesicle-integrated device was able to detect 1-octen-3-ol with excellent sensitivity and selectivity, similar to the original olfactory system. This system can be effectively utilized for the real-time measurement of fungal contamination in grain.