| As an in-situ electrochemical testing methods, the electrochemical quartz crystal impedance system can be used to measure changes in electrode mass, solution viscosity and density, interfacial dielectric properties by monitoring quartz electroacoustic impedance spectroscopy, electrochemical impedance spectrum etc. It has advantages of convenient operation, high sensitivity, capability of providing multiple in-situ parameters and facile automatization. The scanning electrochemical microscopy (SECM) has been widely used for studies of localized electrochemical phenomena and characterization of ions transport across liquid/liquid interfaces, etc. The studies in this thesis are summarized as follows.1. The recent researches using piezoelectric quartz crystal microbalance and scanning electrochemical microscopy are briefly reviewed.2. By combining the piezoelectric quartz crystal impedance (PQCI) and electrochemical impedance spectroscopy (EIS) measurements, we conducted a comparative study on polyaniline degradation in different media, HC1O4 and H2SO4, and on different piezoelectric quartz crystal (PQC) electrodes, Pt and Au. It is concluded that (1) the PANI film grown on an Au electrode is more stable than that on a Pt electrode; (2) the PANI degradation reaction abides by the zero-order kinetic law in HClO4with rate constants from 0.17 to 2.25 Hz s-1 on Pt and 0.16 to 0.83 Hz s-1 on Au, but the first-order kinetic law in H2SO4 with rateconstants from 2.61 10-3 to 7.00 10-3 s-1 on Pt and 1.00 10-3 to 5.00 10-3 s-1 on Au at different ion concentrations. The contrary effects of C1O4- and SO42- on PANI degradation may be understood from the Hofmeister series of anions; (3) the dissolution of the PANI-film bulk, the increase of film porosity and the film attenuation occurred simultaneously during degradation via systematic analyses of the motional resistance and electrochemical impedance spectraresponses., etc.3. Three new protocols for the preparation of conducting genocomposite materials have been described, on the basis of the incorporation of DNA dopants in polypyrrole or poly(n-methylpyrrole) network. The procedures of modification and ion-exchange properties of DNA-modified electrodes were characterized using an electrochemical quartz crystal impedance system (EQCIS). Three target molecules, methylene blue (MB), brilliant cresyl blue (BCB) and adriamycin (DXH), were used to examine the performance of DNA-modified electrodes. The molar ratios of target molecules to DNA at electrodes obtained via the Sauerbrey equation are in good accordance with the reference values. The kinetic parameters for the target-molecules/DNA interactions were measured from the piezoelectric quartz crystal responses. Hybridization reaction of ssDNA molecules on electrodes with those in solution was carried out and a higher response was observed at the present DNA-modified electrodes.4. Three new strategies for the preparation of RNA-modified electrode have been presented, based on the dip-dry modification of drops of RNA aqueous solution on a reduced polypyrrole film, followed by a strengthened incorporation of RNA anionic moieties into polymer network as dopants via cyclic voltammetric redox switching of the PPy film in water (Au/PPy/RNA(I)) or RNA aqueous solution (Au/PPy/RNA(III)). A direct immobilization of RNA was also conducted via cyclic voltammetric redox switching of a pre-reduced pure PPy film in RNA aqueous solution (Au/PPy/RNA(II)). For comparison, two conventional methods, i.e., direct dip-dry immobilization of RNA on bare gold surfaces, and direct entrapment immobilization of RNA via pyrrole polymerisation in RNA aqueous solution were conducted to confine RNA on electrode surfaces. Three target molecules for RNA, methylene blue (MB), brilliant cresyl blue (BCB) and adriamycin (DXH), were used to examine the performance of RNA-modified electrodes. The molar ratios of target molecules to RNA at electrodes were obt...
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