Graphene Field-Effect Transistor-Based Bioelectronic Tongue for Bitterness Evaluation Using Agonism and Antagonism of Bitter Taste Receptor

Bitterness can provoke unpleasant sensations in humans, posing challenges for food acceptance and medication adherence. Thus, effectively identifying and masking bitter tastes is crucial for enhancing palatability in food and ensuring compliance in pharmaceuticals. This study focuses on leveraging agonism and antagonism of bitter taste receptors at the molecular level to achieve these goals. The research involves developing a bioelectronic tongue capable of characterizing agonism and antagonism of human bitter taste receptors, specifically hTAS2R16 and hTAS2R31. These receptors are expressed using an Escherichia coli system and embedded into nanodiscs (NDs). Subsequently, hTAS2R16- and hTAS2R31-NDs are immobilized on graphene field-effect transistors (FETs) to create the bioelectronic tongues. The developed system demonstrates high sensitivity, detecting bitter agonists such as salicin and saccharin at concentrations as low as 100 femtomolar (fM) in real-time, with exceptional selectivity. Furthermore, the dose-response curves indicate that the antagonists of hTAS2R16 and hTAS2R31 shift the curves and decrease the K values, illustrating effective antagonism-based masking of bitter taste. In conclusion, this bioelectronic tongue shows promise for accurately identifying bitter tastes and evaluating bitterness masking strategies based on the agonism and antagonism of hTAS2Rs. These advancements hold significant potential for improving the sensory properties of foods and enhancing medication palatability in various industries.