公益財団法人セコム科学技術振興財団
助成研究（平成 22 年度―25 年度）

研究課題名
昆虫嗅覚センサ－情報処理による匂い源探索装置の開発

Title
Development of odorant detection system based on insect olfactory sensor

2016 年 9 月
September, 2016
研究代表者：東京大学先端科学技術研究センター、教授、神崎亮平
Ryohei Kanzaki
Research Center for Advanced Science and Technology, The University of Tokyo,
Professor,

Summary
Sensitive and real-time odorant sensing technology is demanded for a safety and security in
our life and an improvement of the life quality, including not only food administration, watercontrol, and monitoring environment of agricultural products but also risk management; i.e.
detection of explosive and drugs in airport; monitoring pollutants in the environment, anddisease diagnosis by the odor. Current odorant sensors based on metal-oxide semiconductor
devices, quartz crystal microbalances, or surface acoustic waves have been used for practicalodorant-detection applications. However, there are some shortages in these odorant sensors. For
example, the lack of the coating materials limits the number of target odorants in the metaloxide semiconductor sensors. The odorant sensor using quart crystal microbalances does nothave enough sensitivity due to the disturbance by humidity. Currently, in order to overcome
these disadvantages, it is required to develop odorant sensors based on innovative sensing
technology that detect various types of odorants with high sensitivity and selectivity inreal-time.
Living organisms, especially insects, are equipped with sophisticated olfactory mechanism toenable them to selectively and sensitively detect various types of odorants. It was reported that
this odorant detection in insects is mainly achieved by odorant receptors that function in theirantennae. Therefore, in this study, focusing on the insect odorant receptors, we aim to develop
odorant sensors that allow detection of various types of odorant with higher performances.
First, in order to create a basic technology for development of odorant sensor elements basedon Sf21 cell lines expressing insect odorant receptors, we established the cell lines expressing
pheromone receptors from the silkmoth, Bombyx mori, to evaluate the performances as odorantsensor elements. The cell lines co-expressing pheromone receptor and co-receptor along withfluorescent indicator protein, GCaMP3, detect corresponding pheromone components byincreasing their fluorescence intensities. The cell lines exhibited dose-dependent responses totarget components with the detection limit of 300 nM (several tens parts per billion (ppb) insolution) and selective responses in accordance with the selectivity intrinsic to the expressedreceptors. In addition, the Sf21 cell lines were available for detecting pheromone components
with invariable responsiveness over at least 2 months, thereby overcoming the short life span ofbiosensors for practical use. From these results, we established the methodology for developing
novel cell-based odorant sensor elements based on Sf21 cell lines expressing insect odorant
receptors.
Next, by using the same method as that used for creating the cell lines expressing pheromone
receptors, we established Sf21 cell lines expressing general odorant receptors from the fruit fly,Drosophila melanogaster, for application to general odorants. The established cell lines werefound to detect general odorants by displaying fluorescent intensity increase. For thedevelopment of odorant sensor elements with higher sensitivity, we established a methodology
to create cell lines that detected general odorant at the scale of ppb in solution by improving
expression vectors of odorant receptor genes and changing the types of fluorescence indicator
proteins. Using this method, we succeeded to create cell lines that detect mold odorants,geosmin and 1-octen-3-ol with detection limit of 300 nM (several ten ppb in solution). The celllines could detect geosmin even in the presence of background odor derived from foods orbeverages, indicating that these cell lines were available as practical odorant sensor elements.
From these results, we demonstrated that our methodology is applicable for developing practicalcell-based odorant sensor elements that detect various types of odorants from pheromones togeneral odorants with high sensitivity and selectivity.
As odor is composed of various types of odorants, odorant sensor needs to be developed byacquiring the signals from array of odorant sensor elements with different odorant selectivity fordiscriminating the odor. Finally, we tried to establish two methodologies for arraying several
cell lines by using microfabrication technique and cell patterning technique. For the
microfabrication techniques, we designed and fabricated polydimethylsiloxane (PDMS)-glass
chip with two microfluidic channels, into which two cell lines were separately integrated. The
chip arraying two cell lines, each of which responds to a specific odorant, succeeded todiscriminate two odorants by showing the patterns of fluorescence intensity change. For the cellpatterning technique, we established a methodology for arraying four cell lines onto a glass
surface by using biocompatible anchor for membrane (BAM) and PDMS sheet. By arraying
four cell lines having different odorant selectivity from each other, we succeeded to develop anodorant sensor array that discriminated four odorants as the fluorescence intensity pattern.
Through these studies, we demonstrated that the use of insect odorant receptors enables us todevelop odorant sensor that combines both high sensitivity and high selectivity. In addition, we
successfully established innovative platform to develop a novel odorant sensor with highperformances exceeding existing odorant sensors.