Enzymatic Synthesis of Electrochemical Sensors

BOD (Myrothecium verrucaria, 2.0 U mg⁻¹, Amano Enzyme Co., Ltd., Nagoya, Japan) was used without further purification. MgOC, with an average pore size of 200 nm, was purchased from Toyo Carbon Co., Ltd., Tokyo, Japan. The GDL was donated by the Freudenberg group (H23C6, Germany). Tripotassium citrate monohydrate, sulfonic acid, hydrochloric acid, 1-methyl-2-pyrrolidone (NMP), tetrabutylammonium bromide (TBAB), and ethanol were purchased from Fujifilm Wako Pure Chemical Industries Ltd., Tsukuba, Japan. 2-Mercaptobenzoic acid (2MBA) was procured from Tokyo Chemical Industry Co., Ltd., Tokyo, Japan. Tetrachloride gold oxide (III) hydrate, Nafion^® perfluorinated resin solution (5%), and 4-mercaptobenzoic acid (4MBA) were purchased from Sigma-Aldrich, Missouri, USA. Poly(vinylidene fluoride) (PVDF, 9305, 5 wt% in NMP) was donated by Kureha Co., Ltd., Tokyo, Japan.