Combination Of In Situ FTIR Spectra And Electrochemical Quartz Crystal Microbalance And Its Applications To Several Biological And Chemical Systems

In situ Fourier transformation infrared (FTIR) reflectionspectroelectrochemistry is a useful and powerful tool to study the ology of thesurface. It can provide the information about the interface of solid/liquid andabout the reaction kinetics on the electrodes. In situ Fourier transforminfrared-attenuated total reflectance (FTIR-ATR) measurement is nondestructiveto the samples and the samples need no chemical pretreatment. FTIR-ATR hasbeen applied to in situ study the chemical and biochemical process and theadsorption occurring on the liquid/solid interface. The electrochemical quartzcrystal microbalance (EQCM) can be used to synchronously determine multiplechemical/physical parameters and study materials characteristics during anelectrochemical perturbation, such as electrode-mass changes down to thenanogram level, the elasticity of modified films and the solution viscosity anddensity.Combination techniques of piezoelectric sensor and spectrumelectrochemistry can provide multidimentional information during the chemicaland biochemical process and help us to understand the reaction on theliquid/solid interace more adequately and reliably. In this thesis, we studied thecombination of EQCM and in situ FTIR techniques, and applied thecombination techniques to study the adsorption of protein on biomaterial, theredox of small organic molecule and the electrosynthesis of new polymer.The main content of this dissertation are summarized as follows: 1. The recent researches using in situ FTIR techniques and EQCM are brieflyreviewed.2. The electrochemical piezoelectric quartz crystal impedance (EQCI), acombined technique of piezoelectric quartz crystal impedance (PQCI) andelectrochemical impedance (EI), and FTIR-ATR spectroscopy were utilizedto study in situ adsorption of fibrinogen onto biomaterial surfaces of TiO₂ andhydroxyapatite (Ca₁₀(PO₄)₆(OH)₂). The adsorption kinetics and mechanism offibrinogen adsorption onto these biomaterial surfaces were investigated. TheEQCI and FTIR-ATR measurement results suggested that two consecutivesteps occurred during the adsorption of fibrinogen onto TiO₂ andhydroxyapatite (HAP) films. The fibrinogen molecules were firstly adsorbedonto the films. And then rearrangement of adsorbed fibrinogen ormulti-layered adsorption occurred. The FTIR-ATR spectroscopy studies alsoshowed that the structure of the biomaterials has affected the adsorptionkinetics and the secondary structure of the adsorbed fibrinogen molecules.More fibrinogen molecules were adsorbed onto HAP surface and the secondstructure of the fibrinogen molecules adsorbed onto HAP surface changedmore notably.3. In situ FTIR spectroelectrochemistry and EQCM were used to study theelectrochemical hehaviors of L-Tryptophan (Trp) on polycrystalline Auelectrode and PQC Au electrode in alkaline media. The electrochemicalredox process of L-Tryptophan was studied under different oxidationpotentials in NaOH solution and in electrolyte solutions with different pHvalue by applying cycle voltammetry scan. The resultes showed that theelectro-oxidation of L-Tryptophan was irreversible involving transfer ofprotons. There was polymer (poly(Trp)) deposited on the Au electrode surface which induced by the redoxtion of L-Tryptophan. The EQCM andin stiu FTIR spectra results show that the redox process of poly(Trp) may wasalso irreversible. And the electrochemical reaction of anionic species wereblocked by the poly(Trp) film when the poly(Trp) modified electrode CVin the K₃Fe(CN)₆/K₄Fe(CN)₆ solution.4. The homopolymerization and copolymerization of o-toluidine (OT) ando-aminophenol (OAP) were studied in H₂SO₄ solution with in situpiezoelectric FTIR spectroelectrochemisty methods. The films were obtainedby applying cycle voltammetry scan at the rate 50 mV s^-1 between -0.1 to 0.9V vs. Ag/AgCl electrode in 0.5 M H₂SO₄ solution. The results showed thatthe electrochemical properties of the copolymer (poly(OT-co-OAP)) wasdifferent from that of the two polymers obtained from single monomer (POTor POAP). The copolymerization speeds were notablely affected by the feedratio of the monomers. Poly(OT-co-OAP) obtained under proper conditionswas electrochemically active at a broad pH range. Poly(OT-co-OAP) is morestable than POT and POAP as well. POT, POAP and poly(OT-co-OAP) werestudied with in situ piezoelectric FTIR spectroelectrochemistry methods. TheFTIR spectroscopic results and frequency shiftes indicate that the anion ionscan dope into the three polymers accompanying theprotonation/deprotonation reaction process. The copolymer formed throughhead-to-tail coupling of the two monomers via -NH- groups was a newpolymer rather than a mixture of homopolymers.