聚吖啶黃素及 NDGA/Nafion 與 NDGA/FAD 複合薄膜修飾電極之製備及電催化性質之研究

Abstract

Part Ⅰ. Polymerization of acriflavine performed in acidic aqueous solution produced thin one redox couple electrochemically active film. The electrochemical quartz crystal microbalance and cyclic voltammetry were used to study the in situ growth of the poly(acriflavine) film. The polymer films were more stable in acidic solutions as their formal potentials being pH dependent with a slope close to –60 mV/pH.The film was produced on glassy carbon, gold, and transparent semiconductor tin(IV) oxide electrodes. The modified film was electrocatalytically oxidation active for NADH in acidic and neutral aqueous solutions, as the electrocatalytic oxidation current developed from the anodic peak of the redox couple. The electrocatalytic oxidation of SO32- and electrocatalytic reduction of NO2-, SO52- and S2O82- by the poly(acriflavine) film in acidic aqueous solutions also showed the electrocatalytic reaction activity. The electrocatalytic oxidation of SO52- was investigated using the UV–visible absorption spectroscopy and the stopped-flow kinetic method. While the electrocatalytic oxidation of NADH was investigated using the cyclic voltammetry and the Chronoamperometric method. Part Ⅱ. The electrochemically active films of Nordihydroguaiaretic acid (NDGA,1,4-Bis(3,4-dihydroxyphenyl)2.3-dimethylbutane) film modified electrodes can produce by direct deposition on nafion modified electrodes from the Nordihydroguaiaretic acid. The deposition of NDGA/nafion films are stable and show obvious electrochemical activity in various pH aqueous solutions. An electrochemical quartz crystal microbalance and cyclic voltammetry were used to study the in situ growth of NDGA/nafion films. When NDGA/nafion films are prepared and transferred to aqueous solutions at various pH, the formal potential was found to be pH dependent. NDGA/nafion films were electrocatalytically oxidation active for dopamine, epinephrine, and norepinephrine in aqueous solutions, with the electrocatalytic oxidation current developing through the oxidized form of NDGA/nafion film. NDGA/nafion films also shows reversible electrocatalytic properties. Such films electrocatalytically reduce those oxidation products of dopamine, epinephrine, and norepinephrine that are produced from the electrocatalytic oxidation of these compounds by a NDGA/nafion film. NDGA/nafion modified films are also electrocatalytically oxidation active for the mixture of dopamine and ascorbic acid and their electrochemical properties show the reaction of dopamine quinone with ascorbic acid, This reaction was investigated using the rotating ring-disk electrode method. Part Ⅲ. Preparation of nordihydroguaiaretic acid performed in neutral aqueous solution produced thin one redox couple electrochemically active film. The electrochemical quartz crystal microbalance and cyclic voltammetry were used to study the in situ growth of the nordihydroguaiaretic acid film. The modified film was electrocatalytically oxidation of NADH to NAD+ and the electrocatalytic oxidation of ascorbic acid, dopamine, and N2H4 by the nordihydroguaiaretic acid film in neutral aqueous solutions showed the electrocatalytic reaction activity. Well-separated voltammetric peaks were observed for dopamine with uric acid and ascorbic acid with uric acid using the NDGA/GC modified electrodes. Hybrid films composed of nordihydroguaiaretic acid- flavin adenine dinucleotide (FAD) adsorbed film modified electrodes have been prepared in neutral aqueous solutions. The hybrid NDGA/ FAD film showed two redox couples. When transferred to various aqueous acidic solutions, the two redox couples and the formal potentials of the hybrid films were observed to be pH-dependent. The electrocatalytic oxidation and reduction of NADH and NAD+ by a NDGA/ FAD hybrid film in neutral aqueous solutions was carried out. The electrocatalytic oxidation of NADH and the reversible electrocatalytic reactions of NADH / NAD+ using a NDGA/ FAD hybrid film were found active.