| Glutathione (GTh), homocysteine (HCy) and cysteine (Cys) are three of the most important small molecule thiols in living organism. Since the changes of concentration of these thiols have a direct relationship with many diseases, real-time detection of thiols, especially determination of the several typical small-molecule thiols at the same time or selective detection one of them, plays an important role in diagnosing some diseases. Nanomaterials have been studied extensively due to their unique properties which different from the bulk materials. Also they indicate the wide application prospect in the area of electrocatalysis and biosensor. The electrochemical analyses towards several important thiols with nanomaterial modified electrode were researched in this thesis.This graduation thesis includes several sections, as follows:1. The importance of detecting bio-thiols, the current research situation and several traditional determination methods were described in this part. In addition, the advantages of using of nanomaterial modified electrode electrocatalytical determination of bio-thiols were analyzed. And in the end, the research mentality and research target of this thesis were also introduced.2. In this part, the electrochemical behavior of L-Cys was studied on the Nd2O3nanoparticles modified carbon paste electrode. Rare Earth Elements express special optical, electrical, and magnetic properties own to their special electronic configuration. They show good electrocatalytic activities toward biomolecules.3. Preparation and characterization of multifunctional polypyrrole-Au coated NiO nanocomposites and study of their electrocatalysis toward several important bio-thiols.In this study, polypyrrole (PPy) and Au were co-deposited onto the surface of NiO nanoparticles to prepare multifunctional nanocomposites for electroanalysis applications. It’s proposed that each component in NiO/PPy-Au nanocomposites plays a great role on their electrocatalytical performance where conductive PPy helps to immobilize the nanocomposites onto the electrode surface due to its outstanding adherence ability, NiO does to mediate the oxidation of thiols through the redox couple of Ni(OH)2/NiOOH, and Au does to the electron transfer of nanocomposites and the redox transformation between Ni(OH)2and NiOOH due to its high conductivity. The obtained NiO/PPy-Au nanocomposites were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, UV-vis spectroscopy and powder X-ray diffraction. The obtained NiO/PPy-Au nanocomposites could be easily immobilized onto the surface of glassy carbon electrodes. They exhibit excellent electrochemical property for the redox couple Ni(OH)2/NiOOH and high electrocatalytical oxidation toward some typical and important biological thiols such as Cys, HCy and GTh. Cys could be selectively detected at the applied potential of0.15V where the interference of HCy and GTh is somewhat low. The NiO/PPy-Au nanocomposites modified electrode also shows high electrochemical response to the produced thiocholine from the hydrolysis reaction of acetylcholinesterase.4. Synthesis and assembly of ultrathin film of Ni(OH)2nanoparticles at gas/liquid interface, its high electrocatalytical oxidation toward bio-thiols and selective determination of Cys.In this part, a facile strategy was reported to synthesize and assemble a stable ultrathin film of Ni(OH)2nanoparticles at gas/liquid interface where the aqueous phase contained Ni2+and the organic phase was composed of triethylamine toluene solution. The ultrathin film of Ni(OH)2nanoparticles that precipitated at the interface was transferred onto the electrode surface for the electrocatalysis of bio-thiols and selective electroanalysis of Cys. The preparation of Ni(OH)2ultrathin film and its transfer to an electrode substrate is very simple. The obtained Ni(OH)2ultrathin film modified electrodes are stable, showing high electrochemical oxidation toward bio-thiols and good selectivity toward Cys in phosphate buffered solution of pH7.5. |
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