Study Of Modified Electrodes Based On Nanomaterials And Application In Electroanalytical Chemistry Of Proteins

Nano science and technology has entered the limelight and has been investigated extensively in recent years. During the past decade, nanomaterials have brought new chances and challenges to physics, chemistry, biology as well as all sectors of technology. Nano is in fashion, for there are fashion trends even in scientific world. We are on the verge of a new scientific and technological era, the standard of which is the nanometer. In recent work, it has been discovered that materials in the nanometric size (0.1-100 nm) regime display size-dependent optical, magnetic, electronic, and chemical properties. Between these extremes, nanomaterials have largely unknown chemical and physical properties which differ greatly from the bulk substances. Therefore, nanoparticles can be applied to many fields, such as optical devices, electronic devices, catalysis, sensor technology, and biomolecular labeling, etc., which is also the reason that a burst of research activities have been focused on nanoparticles. Modified electrodes based on nanomaterials combined with high surface area and good electrocatalytic abilities that can largely improved electrical responses and the detection sensitivity. Today, many wonderful nanomaterials have been applied in electroanalytical chemistry and some important progresses along these lines have recently achieved.Since the successful finish of the DNA coding sequence analysis of the entire human genome, the challenge ahead will no longer be the elucidation of the DNA coding sequence, but understanding how its gene sequences are expressed. Studying this process at the protein level, termed proteomics, is expected to be a more complex task, and it has gained considerable attention recently. In the bioelectrochemistry field, the direct electrochemistry of redox proteins arouses many scientists' interest. This interest is due to the direct electron transfer between aprotein molecule (the redox active group) and an electrode, which can serve as a model system to help understand electron transfer mechanisms and physiological structure-function relationship in biological systems, and establish a foundation for fabricating new kinds of biosensors or enzymatic biosensors. However, only a few redox proteins perform electroactive behaviors at bare conventional electrode surfaces because of three reasons: first, the redox active prosthetic groups are embedded deeply in the protein structure; second, unfavorable orientations on electrode surfaces make it more difficult for protein molecules to perferm redox reactions; third, the adsorption induced unfolding poisoning, deactivation as well as denaturation.The nanostructure greatly enhances the active surface available for protein binding over the geometrical area, and maintain the proteins' physiologically activity without detectable denaturation. This dissertation research focuses on developing modified electrodes based on nanomaterials, which is one of most active areas in electroanalytical chemistry of proteins. This dissertation is adhering to an organic combination of electroanalytical chemistry, nanotechnology and proteins. Of course, it is a new area worthy of attention and it also helps to set up new methods, new techniques and new theories. The details are given as follows:1 Fabrication of ZnO Nanorod Modified Electrode and Its Application to the Direct Electrochemical Determination of Hemoglobin and Cytochrome cA novel electrochemical method as a sensitive and convenient technique for the determination of heme proteins based on their interaction with ZnO nanorods was developed. A ZnO nanorod modified glassy carbon electrode (ZnO/GCE) was prepared and the electrochemical behaviors of heme proteins, such as hemoglobin (Hb) and cytochrome c (Cyt-c), on this modified electrode have been studied. The results showed that both Hb and Cyt-c could be oxidized on the modified electrode and the oxidation currents were linear to the concentrations of the analytes in aqueous solutions. In addition, the results of flow injection analysis (FIA) further suggested the h...