Hyun Seok Song,†,∥ Oh Seok Kwon,‡,∥ Sang Hun Lee,† Seon Joo Park,‡ Un-Kyung Kim,§ Jyongsik Jang,*,‡ and Tai Hyun Park*,†
†School of Chemical and Biological Engineering, Bio-MAX Institute, Seoul National University, Seoul 151-744, Republic of Korea
‡World Class University program of Chemical Convergence for Energy & Environment, School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Republic of Korea
§Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu 702-701, Republic of Korea
These authors contributed equally to this work.
* Corresponding Authors : Jyongsik Jang and Tai Hyun Park
In this study, we developed a human taste receptor protein, hTAS2R38-functionalized carboxylated polypyrrole nanotube (CPNT)-field effect transistor (FET) as a nanobioelectronic tongue (nbe-tongue) that displayed human-like performance with high sensitivity and selectivity. Taster type (PAV) and nontaster type (AVI) hTAS2R38s were expressed in Escherichia coli (E. coli) at a high level and immobilized on a CPNT-FET sensor platform. Among the various tastants examined, PAV-CPNT-FET exclusively responded to target bitterness compounds, phenylthiocarbamide (PTC) and propylthiouracil (PROP), with high sensitivity at concentrations as low as 1 fM. However, no significant changes were observed in the AVI-CPNT-FET in response to the target bitter tastants. This nbe-tongue exhibited different bitter-taste perception of compounds containing thiourea (N-C＝S) moieties such as PTC, PROP, and antithyroid toxin in vegetables, which corresponded to the haplotype of hTAS2R38 immobilized on CPNTs. This correlation with the type of receptor is very similar to the human taste system. Thus, the artificial taste sensor developed in this study allowed for the efficient detection of target tastants in mixture and real food sample with a human-like performance and high sensitivity. Furthermore, our nbe-tongue could be utilized as a substitute for cell-based assays and to better understand the mechanisms of human taste.
Keywords: Human taste receptor; conducting polymer; nanotube; field-effect transistor; nanobioelectronic tongue; antithyroid toxin