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Recently, various bioelectronic nose devices based on human receptors were developed for mimicking a human olfactory system. However, such bioelectronic nose devices could operate in an aqueous solution, and it was often very difficult to detect insoluble gas odorants. Here, we report a portable bioelectronic nose platform utilizing a receptor protein-based bioelectronic nose device as a sensor and odorant-binding protein (OBP) as a transporter for insoluble gas molecules in a solution, mimicking the functionality of human mucosa. Our bioelectronic nose platform based on I7 receptor exhibited dose-dependent responses to octanal gas in real time. Furthermore, the bioelectronic platforms with OBP exhibited the sensor sensitivity improved by ∼100% compared with those without OBP. We also demonstrated the detection of odorant gas from real orange juice and found that the electrical responses of the devices with OBP were much larger than those without OBP. Since our bioelectronic nose platform allows us to directly detect gas-phase odorant molecules including a rather insoluble species, it could be a powerful tool for versatile applications and basic research based on a bioelectronic nose.

Nerve agents are organophosphorus toxic chemicals that can inhibit acetylcholinesterase, leading to paralysis of the nervous system and death. Early detection of nerve agents is important for safety issues. Dimethyl methylphosphonate (DMMP) is widely used as a simulant of nerve agents, and many studies have been conducted using DMMP as a substitute for detecting nerve agents. Despite many studies on sensors for detecting DMMP, they have limitations in sensitivity and selectivity. To overcome these limitations, a nickel-decorated reduced graphene oxide (Ni-rGO) sensor with human olfactory receptor hOR2T7 nanodiscs was utilized to create a bioelectronic nose platform for DMMP gas detection. hOR2T7 was produced and reconstituted into nanodiscs for enhancing the sensor’s stability, especially for detection in a gas phase. It could detect DMMP gas selectively and repeatedly at a concentration of 1 ppb. This sensitive and selective bioelectronic nose can be applied as a practical tool for the detection of gaseous chemical warfare agents in military and safety fields.