title: Selective nitrate detection by an enzymatic sensor based on an extended-gate type organic field-effect transistor.
abstract: First selective nitrate biosensor device based on an extended-gate type organic field-effect transistor (OFET) is reported. The fabricated sensor device consists of the extended-gate electrode functionalized by a nitrate reductase with a mediator (=a bipyridinium derivative) and an OFET-based transducer. The mechanism of the nitrate detection can be explained by an electron-relay on the extended-gate electrode, resulting in changes of the electric properties of the OFET. The detection limit of nitrate in water is estimated to be 45 ppb, which suggests that the sensitivity of our fabricated sensor is comparable to those of some conventional detection methods. As a practical application of the OFET sensor, the nitrate detection in diluted human saliva has been successfully demonstrated; the results agreed well with those by conventional colorimetric measurement. The advantages of OFETs are printability, mechanical flexibility, stretchability and disposability, meaning that the fabricated OFET could open up a new approach for low-cost electronic devices toward on-site detection of nitrate in aqueous media.
authors.affiliation: Research Center for Organic Electronics (ROEL), Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan. Electronic address: tminami@yz.yamagata-u.ac.jp.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Minami
authors.affiliation: Research Center for Organic Electronics (ROEL), Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan.
authors.forename: Yui
authors.initials: Y
authors.lastname: Sasaki
authors.affiliation: Research Center for Organic Electronics (ROEL), Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan.
authors.forename: Tsukuru
authors.initials: T
authors.lastname: Minamiki
authors.affiliation: Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14 Hayashi, Takamatsu, Kagawa 761-0395, Japan.
authors.forename: Shin-Ichi
authors.initials: SI
authors.lastname: Wakida
authors.affiliation: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan.
authors.forename: Ryoji
authors.initials: R
authors.lastname: Kurita
authors.affiliation: Research Center for Organic Electronics (ROEL), Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan; Advanced Science Research Laboratory, Saitama Institute of Technology, Fukaya, Saitama 369-0293, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Niwa
authors.affiliation: Research Center for Organic Electronics (ROEL), Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan.
authors.forename: Shizuo
authors.initials: S
authors.lastname: Tokito
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000737:chemistry; D004867:Equipment Design; D006801:Humans; D057230:Limit of Detection; D050901:Nitrate Reductase / Q000737:chemistry; D009566:Nitrates / Q000032:analysis*; D012463:Saliva / Q000737:chemistry*; D014173:Transistors, Electronic; D014867:Water / Q000032:analysis*
chemical_list: D004800:Enzymes, Immobilized; D009566:Nitrates; D014867:Water; D050901:Nitrate Reductase
keywords: Enzymatic sensor; Nitrate; Nitrate reductase; Organic electronics; Organic field-effect transistor