Preliminary Studies Of EQCM And Fluorescence Spectrophotometric Methods Toward Biochemical Analysis

Electrochemical quartz crystal microbalance (EQCM) is a powerful tool to study chemically-modified electrodes, which can be used to synchronously study the multiple chemical/physical parameters and materials characteristics during an electrochemical perturbation, such as electrode-mass changes down to the nanogram level, the solution viscosity and density, and the elasticity of modified films. Piezoelectric spectroelectrochemistry, which combines piezoelectric sensor with spectroelectrochemistry, as a new technique, can provide piezoelectric, spectral and electrochemical information in one experiment and thus lead to less ambiguity in the description of a practical electrochemical process.The studies in the thesis are summarized as follows:1. The recent progress of spectroelectrochemistry, EQCM, and piezoelectric spectroelectrochemistry researches are reviewed.2. The fluorescence quenching of pyridoxal in NaOH solution by glycine, alanine, cysteine, cystine, glutathione (reduced and oxidized forms) was investigated. A general equation for investigating interactions between molecules via fluorescence quenching method was deduced, and the binding constants (K) and binding ratios (n) of pyridoxal to these amino acids and glutathione were thus obtained. The fluorescent characteristics of pyridoxal in alkaline solutions and related UV- absorption influence from amino acids and glutathione were examined. The thermodynamic functions of the reaction of glycine with pyridoxal were measured and discussed.3. The electrochemical piezoelectric quartz crystal (PQC) impedance analysiswas used to investigate the effects of several additives on the polymer chain structure and the precipitation of phenazinehydrine charge-transfer complexes (CTC) during the cyclic voltammetric deposition of poly(o-phenylenediamine) (PoPD) thin films at Au electrodes. Two parent solutions, acidic (0.10 nol L'1 H2SO4, mainly for examining the CTC precipitation) and neutral (0.1 mol L" phosphate buffer, pH 7.0, mainly for examining the polymer structure) aqueous solutions, and the concentration modulations for Na2SC>4, K2SO4, glucose, sodium gluconate, tannic acid, sodium heparin, or glucose oxidase (GOD) as additives, were chosen for such purposes. The results show the concentration increases for all anions (especially those of large sizes) weakened the CTC precipitation, similar anionic effects on weakening the CTC precipitation were found during redox switching of phenazine too. In comparison with the absence of the large sized anions, the pendant amino groups (reflecting the polyaniline-like chain structure) in as-prepared PoPD thin films became doubled or tripled in the neutral polymerization bath containing sub-g L"1 sodium heparin or GOD. The anionic effects on the PoPD structure and related CTC precipitation have been reasonably explained via the protonation at nitrogen atoms of the monomer/oligomers/polymers, induced anion incorporation and steric hindrance in related reactions/processes. The pedant amino groups in PoPD multiplied simply by the anionic effect of GOD were active in the aminocarbonyl reaction with glutaraldehyde, and thus the glutaraldehyde-assisted immobilization of more GOD molecules in PoPD was briefly demonstrated here for glucose biosensing with satisfactory results.4. Piezoelectric reflectance spectroelectrochemistry, which combines...