Piezoelectric Electrochemistry And Fluorescence Spectral Studies On Several Biological Molecular Systems

Piezoelectric quartz crystal(PQC) sensor can detect dynamically anelectrode-mass change down to the nanogram level (generally equivalent tomonolayer or submonolayer modification), and its combination withelectrochemistry, piezoelectric electrochemistry, is capable of providingmultiple in situ information of the investigated system. The fluorescencespectral method has many advantages such as high sensitivity, good specificity,small-quantity sample and simple manipulation. In this thesis, piezoelectricelectrochemistry and fluorescence spectral were used to study several biologicalmolecular systems, and the main contents are as follows:1. The principles and applications of the piezoelectric quartz crystal sensor andfluorescence spectral method for biochemical studies are briefly reviewed.2. We report for the first time the effective catalytic electrooxidation ofnicotinamide adenine dinucleotide (NADH) on the pencil 8B-scrawled goldelectrode of an electrochemical quartz crystal microbalance (EQCM). TheEQCM allowed us to quantitatively evaluate the catalytic activity of thepencil-scrawled Au electrode. Sensitive amperometric detection of NADHwas achieved at the gold electrode with saturated pencil modification, withlow detection potential (0.4 V versus SCE), low detection limit (0.08μmolL^-1) and wide linear range (0.2～710μmol L^-1). The fluoroelectrochemicalmeasurements of NADH at bare and pencil-modified gold electrodes werealso conducted with satisfactory results.3. Electrochemical quartz crystal impedance analysis (EQCIA) technique wasutilized to monitor in situ the adsorption of rutin (RT) onto a CNTs-modifiedgold electrode and study the binding process of solution hemoglobin (Hb) toRT immobilized on the electrode. Time courses of the EQCI parameters including crystal resonant frequency were simultaneously obtained duringthe RT adsorption and Hb-RT binding. The average binding molar ratio ofadsorbed RT to Hb and the association constant for the binding wereestimated. Comparable results were obtained from fluorescence quenchingmeasurements in mixed solutions containing RT of fixed concentration andHb of varying concentrations, demonstrating that the interfacial RT herebehaved equivalently in the RT-Hb binding activity as the solution one.4. The EQCIA technique was utilized to monitor in situ the adsorption of themixture of glucose oxidase (GOD) and sodium dodecyle benzene sulfonate(SDBS) onto a SDBS/CNTs modified gold electrode, and the enzymaticactivity of the immobilized GOD as a function of its direct electrochemistrywas quantitatively examined. Compared with the bare gold electrode atwhich a little GOD was adsorbed and the direct electrochemistry of theadsorbed GOD was negligible, the electroactivity of adsorbed GOD weregreatly enhanced when the GOD was mixed with the SDBS and thenadsorbed onto the SDBS/CNTs modified Au electrode. However, the enzymespecific activity (ESA) of the adsorbed GOD was largely decreased.