Bioelectronics for bitterness-based phytocompound detection using human bitter taste receptor nanodiscs

Various organisms produce several products to defend themselves from the environment and enemies. These natural products have pharmacological and biological activities and are used for therapeutic purposes, retaining bitter taste because of chemical defense mechanisms. Cnicin is a plant-derived bitter sesquiterpene lactone with pharmacological characteristics such as anti-bacterial, anti-myeloma, anti-cancer, anti-tumor, anti-oxidant, anti-inflammatory, allelopathic, and cytotoxic properties. Although many studies have focused on cnicin detection, they have limitations and novel cnicin-detecting strategies are required. In this study, we developed the bioelectronics for screening cnicin using its distinct taste. hTAS2R46 was produced using an Escherichia coli expression system and reconstituted into nanodiscs (NDs). The binding sites and energy between hTAS2R46 and cnicin were investigated using biosimulations. hTAS2R46-NDs were combined with a side-gated graphene micropatterned field-effect transistor (SGMFET) to construct hTAS2R46-NDs bioelectronics. The construction was examined by chemical and electrical characterization. The developed system exhibited unprecedented performance, 10 fM limit of detection, rapid response time (within 10 s), 0.1354 pM^-1 equilibrium constant, and high selectivity. Furthermore, the system was stable as the sensing performance was maintained for 15 days. Therefore, the hTAS2R46-NDs bioelectronics can be utilized to screen cnicin from natural products and applied in the food and drug industries.