| Among various conducting polymers, poly(3,4-ethylenedioxythiophene)(PEDOT) has become the most attractive one from both fundamental research and practical perspective because of great environmental stability, extraordinary conductivity, excellent transparency, easy film-forming, and friendly biocompatibility. In the past thirty years of research and development, a large number of potential applications exist in light emitting diode, supercapacitors, solar cell, antistatic coating, and chemo/bio-sensors devices etc. based on PEDOT. However, some limitations and shortcoming still exist for PEDOT as sensing materials, such as1) low aqueous solubility of3,4-ethylenedioxythiophene (EDOT) monomer;2) poor biological compatibility;3) toxic to some bioactive species. In its well-known study, the one of most attractive properties of PEDOT is that its properties can be tuned by grafting various functional groups. Therefore, the studies of the design and synthesis of introduction of functional groups to EDOT side chain are currently ongoing and have made encouraging progress for solving the above-mentioned problems. In addition, electrochemical chemo/bio-sensors have been extensively applied in environmental monitoring, biopharmaceuticals and clinical medicine, food safety and biofermentation, and a plenty of other related and similar fields owing to their facile preparation, low cost, portability, specificity, sensitivity, selectivity, high efficiency, and potential for consecutive, fast, real-time in-vivo electrochemical detection and analysis. The thesis mainly focused on the synthesis and electropolymerization of synthetic EDOT derivatives and detailed characterization of the corresponding polymers. And then kinds of electrochemical chemo/bio-sensors and optical sensors are facilely explored for the sensitive determination of biomolecules, drug molecules, environmental pollutants, and metal ions using the resulting polymer combine with different materials including enzyme, carbon materials, metal, and so on. Finally, the electrochemical behavior and parametric characterization as well as the performance of these as-prepared sensors are studied in detail. 1. PEDOT can be performed on gold electrode with electropolymerization of EDOT monomer to form the PEDOT modified gold electrode. The modified electrode can be used for the quantification of macrolide antibiotics of roxithromycin (RM) in phosphate-buffered solution (PBS, pH7.0) by cyclic voltammetry, and the oxidative mechanism of RM at the PEDOT modified electrode is investigated. Under optimal conditions, the current response of the as-prepared modified electrode towards RM is linear from0.08to20μM (R2=0.9996) with a detection limit of0.0267μM, and a high sensitivity of0.9921μA μM-1. Moreover, the voltammetric determination of RM content in its commercial capsule samples by using the fabricated electrochemical sensor also showed a satisfactory result.2.2’-Chloromethyl-3,4-ethylenedioxythiophene (EDOT-MeCl) is synthesized using3,4-dibromothiophene as the starting material and its electrochemical polymerization behavior in dichloromethane containing suitable tetrabutylammonium tetrafluoroborate is studied. Subsequently, the properties of the obtained polymer film (PEDOT-MeCl) are characterized by different methods such as cyclic voltammetry, electrochemical impedance spectroscopy, fourier transform infrared, ultraviolet-visible, fluorescent, thermogravimetric analysis, and scanning electron microscope, the results display that PEDOT-MeCl film has a good reversible redox activity, remarkable capacitance properties, good thermal stability. In addition, the rough and porous surface morphology of PEDOT-MeCl film is extremely beneficial for improvement of adsorption performance. Finally, the PEDOT-MeCl film is employed for the fabrication of the sensing electrode, and dopamine (DA) is chosen as a model analyte. The modified electrode displays a linear function of the DA concentration range from0.079to672.9μM (R2=0.9989). The current sensitivity is calculated to be0.002μAμM-1, and the detection limit is found to be0.0167μM.3. Then,2’-hydroxymethyl-3,4-ethylenedioxythiophene (EDOTM) is also synthesized when EDOT-MeCl as an intermediate, and the corresponding polymer film (PEDTM) is synthesized successfully by electropolymerization of EDTM monomer in aqueous solution. A stable electrochemical sensor based on as-prepared composite film by layer-by-layer self-assembly technique for determination of catechin (CAT) in0.1M PBS (pH7.0) is developed for the first time, the voltammetric response of as-prepared electrochemical sensor present a good linear relationship with the CAT concentration range from0.0398to40.84μM (R2=0.9997), and its experimental detection limit is0.0133μM. The satisfactory results can be attributed to the synergetic effect of f-SWCNT and PEDTM, in which f-SCNT provides a large surface area to increase the loading amount of CAT with excellent electrocatalytic performance for the determination of CAT. Meanwhile, the electron transfer on the electrode surface can be accelerated and the electrochemical signal is amplified due to the outstanding conductivity of PEDTM layer.4. A water-soluble4-((2,3-dihydrothieno[3,4-b][1,4] dioxin-2-yl) methoxy)-4-oxobutanoic acid (C4-EDOT-COOH) monomer is synthesized through esterification reaction between EDTM and succinic anhydrous. The effect of different pH values on the electropolymerization of C4-EDOT-COOH monomer in micellar solutions of sodium dodecyl sulfate (SDS) is investigated, and the as-prepared polymer film (PC4) is characterized by electrochemical method, infrared spectrum, and scanning electron microscope. The resulting high-quality PC4film as a sensing materials not only can combine with various biologically active species (ascorbate oxidase, L-gluththione) via covalent linkage and inorganic materials (alloy, CNTs, metallic oxide) via layer-by-layer self-assembly for the construction of electrochemical chemo/bio-sensors, but also excellent optical performance of PC4can be employed for the preparation of optical sensors. These as-prepared chemo/bio-sensors can be applied to the simple, fast, and sensitive detection of environmental pollutants, pharmaceuticals, hazardous substances, and biological active substance and nutrients present in food by means of electrochemistry, ultraviolet and fluorescence spectroscopy. All satisfactory results indicate that chemo/bio-sensors based on PC4possess extraordinary chemo/bio sensing performance and enhanced optical response, and these fabricated composites could provide promising platforms for different types of chemo/bio-sensors. |
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