title: Electrochemical properties of honeycomb-like structured HFBI self-organized membranes on HOPG electrodes.
abstract: HFBI (derived from Trichoderma sp.) is a unique structural protein, which forms a self-organized monolayer at both air/water interface and water/solid interfaces in accurate two-dimensional ordered structures. We have taken advantage of the unique functionality of HFBI as a molecular carrier for preparation of ordered molecular phase on solid substrate surfaces. The HFBI molecular carrier can easily form ordered structures; however, the dense molecular layers form an electrochemical barrier between the electrode and solution phase. In this study, the electrochemical properties of HFBI self-organized membrane-covered electrodes were investigated. Wild-type HFBI has balanced positive and negative charges on its surface. Highly oriented pyrolytic graphite (HOPG) electrodes coated with HFBI molecules were investigated electrochemically. To improve the electrochemical properties of this HFBI-coated electrode, the two types of HFBI variants, with oppositely charged surfaces, were prepared genetically. All three types of HFBI-coated HOPG electrode perform electron transfer between the electrode and solution phase through the dense HFBI molecular layer. This is because the HFBI self-organized membrane has a honeycomb-like structure, with penetrating holes. In the cases of HFBI variants, the oppositely charged HFBI membrane phases shown opposite electrochemical behaviors in electrochemical impedance spectroscopy. HFBI is a molecule with a unique structure, and can easily form honeycomb-like structures on solid material surfaces such as electrodes. The molecular membrane phase can be used for electrochemical molecular interfaces.
authors.affiliation: Department of Biological Functions Engineering, Kyushu Institute of Technology, Kitakyushu Science and Research Park, Fukuoka, 808-0196, Japan; Research center for Eco-fitting Technology, Kyushu Institute of Technology, Kitakyushu Science and Research Park, Fukuoka, 808-0196, Japan; Advanced Catalytic Transformation program for Carbon utilization (ACT-C), Japan Science and Technology Agency (JST), Tokyo, 102-0076, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Yamasaki
authors.affiliation: Department of Biological Functions Engineering, Kyushu Institute of Technology, Kitakyushu Science and Research Park, Fukuoka, 808-0196, Japan; Research center for Eco-fitting Technology, Kyushu Institute of Technology, Kitakyushu Science and Research Park, Fukuoka, 808-0196, Japan; Advanced Catalytic Transformation program for Carbon utilization (ACT-C), Japan Science and Technology Agency (JST), Tokyo, 102-0076, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Takatsuji
authors.affiliation: VTT Biotechnology, Espoo, Finland.
authors.forename: Michael
authors.initials: M
authors.lastname: Lienemann
authors.affiliation: Kanazawa University, Ishikawa, 920-1192, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Asakawa
authors.affiliation: Kanazawa University, Ishikawa, 920-1192, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Fukuma
authors.affiliation: VTT Biotechnology, Espoo, Finland; Aalto University, School of Chemical Technology, Kemistintie 2, FI-00076, Espoo, Finland.
authors.forename: Markus
authors.initials: M
authors.lastname: Linder
authors.affiliation: Department of Biological Functions Engineering, Kyushu Institute of Technology, Kitakyushu Science and Research Park, Fukuoka, 808-0196, Japan; Research center for Eco-fitting Technology, Kyushu Institute of Technology, Kitakyushu Science and Research Park, Fukuoka, 808-0196, Japan; Advanced Catalytic Transformation program for Carbon utilization (ACT-C), Japan Science and Technology Agency (JST), Tokyo, 102-0076, Japan. Electronic address: haruyama@life.kyutech.ac.jp.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Haruyama
mesh_terms: D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D007093:Imidazoles / Q000737:chemistry*; D008567:Membranes, Artificial; D005466:Fluorocarbons
chemical_list: D007093:Imidazoles; D008567:Membranes, Artificial; C046634:1-(heptafluorobutyryl)imidazole; D005466:Fluorocarbons
keywords: Electrochemical; Engineered protein; HFBI; Impedance; Modified electrode; Self-assembled membrane