Chemically and biochemically modified electrode and ultramicroelectrode for the detection of redox-active biomessengers : preparation, characterization and application
by Jianhong Pei
THESIS
1997
Ph.D. Chemistry
xviii, 498 leaves : ill., photos ; 30 cm
Abstract
A novel class of chemically modified electrodes (CMEs) were developed based on the platinum complexes (Magnus' green salts) and their various analogous compounds. The reasons for choosing this kind of materials as modifiers for the preparation of CME are: (a) to the best of our knowledge, they have received little attention in the use as electrode modifiers; (b) they are anticipated to be good electron mediators/distributors attributable to the well defined Pt4+/Pt2+ electrochemical couple; (c) the Pt4+/Pt2+ couple has documented and well-established catalytic behaviors; and (d) they are a kind of inorganic polymers, which have been extensively studied in optical and electronic devices. They display one-dimensional structure and easily be deposited on electrode surfaces. Various surface...[ Read more ]
A novel class of chemically modified electrodes (CMEs) were developed based on the platinum complexes (Magnus' green salts) and their various analogous compounds. The reasons for choosing this kind of materials as modifiers for the preparation of CME are: (a) to the best of our knowledge, they have received little attention in the use as electrode modifiers; (b) they are anticipated to be good electron mediators/distributors attributable to the well defined Pt4+/Pt2+ electrochemical couple; (c) the Pt4+/Pt2+ couple has documented and well-established catalytic behaviors; and (d) they are a kind of inorganic polymers, which have been extensively studied in optical and electronic devices. They display one-dimensional structure and easily be deposited on electrode surfaces. Various surface analysis techniques, such as SEM, EDAX, Raman, XRD, XPS, ToF-SIMS, have been used to characterize the modified films. The electrochemical behaviors of these chemically modified electrodes have also been systematically studied. On the basis of these studies, the mechanism of the electropolymerization on substrate surfaces has been proposed. The electrocatalytic activities of these CMEs have been demonstrated.
Nitric oxide (NO), a free radical-like diatomic molecule, has been established recently as one of the most important cellular messengers in human physiology. The selective, sensitive and in situ detection of NO is very important in understanding its biological roles and shows a great challenge due to its low concentration and fleeting existence. Those CMEs we developed display greatly catalytic activities to the oxidation of NO and can detect NO at nanomolar concentration and with a very fast response. The detection of NO in buffer solutions and in-situ tissue-level samples have been demonstrated in this thesis.
The multi-task detection of these CMEs have been demonstrated by the detection of peroxide and oxygen. These electrodes show good electrochemical sensors for these species. The detection of hydroperoxide in the presence of oxygen makes the electrode promising for use as an enzyme electrode.
The enzymes, glucose oxidase, xanthine oxidase and amino acid oxidase, were immobilized onto the surface of the chemically modified electrode and used for detection of these species. They show very high sensitivity and fast response time.
The chemically modified electrode aad biomodifkd electrude were used as electrochemical sensors and characterized as detectors coupled with flow-injection analysis and high-performance liquid chromatography.
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