| Bio macro molecule including proteins and enzymes are the primary groups of life and they are involved in metabolism and other important physiological processes. Direct electrochemistry of redox proteins and enzymes has aroused great interest in biological and bioelectrochemical fields. Studies on direct electrochemistry of redox proteins/enzymes can be used to extract essential physicochemical data concerning the kinetics and energetics of protein redox reactions, providing mechanistic studies of electron exchange among proteins in biological systems. Moreover, direct electron transfer between immobilized enzyme and underlying electrode can establish a foundation for fabricating new kinds of mediator-free biosensors, biofuel cells, bio-reactors. which are characteristics of electron transter between theire oxidation and reduction states. In a sense, studying on the life process is essentially the research of the electron transfer process in organisms. Therefore, to study the electron transfer process of protein by using electrochemical methods has particular advantages. Ionic liquids (ILs) have been utilized in the fields of electrochemistry and electro ana lysis due to their unique physicochemical properties including higher ionic conductivity, wider electrochemical windows, higher thermal stability and chemical stability, higher dissolved ability, non-volatile and non-toxic. The special characteristics of nanomaterials such as high surface, high catalytic activity and strong affinity also make them the most promising materials used in biosensor, which can greatly enhance the active surface available for protein binding over the geometrical area, accelerate the electronic transfer between protein activity center and the electrodes, and maintain the physiological activity of proteins without detectable denaturation. In this thesis IL and nanomaterials are used as modifiers to fabricate different kinds of proteins modified electrodes and the direct electrochemistry of heme proteins are studied in details. The thesis can be summarized as follows:1. Carbon coated Fe3O4nanospindles (C@Fe3O4NSs) were synthesized by partial reduction of monodispersed hematite nanospindles with carbon coatings and applied to investigate direct electrochemistry of myogbbin (Mb). A novel modified electrode was prepared by applying carbon coated Fe3O4nanospindles, Mb, ionic liquid (IL)1-ethyl-3-methylimidazolium ethylsulfate ([EMIM]EtOSO3) and chitosan (CTS) step by step on the surface of a carbon ionic liquid electrode (CILE) with another ionic liquid1-butyl-3-methylimidazolium tetrafiuoroborate ([BMIM]BF4) as the binder. UV-Vis absorption and FT-IR spectra results indicated that Mb remained its native structure in the composite film. The electrochemical behaviors of Mb in the modified electrode were carefully investigated and the electrochemical parameters were calculated. The modified electrode showed excellent electrocatalytic behaviors to the reduction of trichloroacetic acid (TCA) and the apparent Michaelis-Menten constants (KMappp) was calculated.2. Hollow Co3O4nanospheres was synthesized by hydrothermal method and applied to investigate direct electrochemistry of hemoglobin (Hb). A new electrochemical biosensor was fabricated by using Nafion, hollow CO3O4nanospheres, ionic liquid (IL) and hemoglobin (Hb) nanocomposite materials modified carbon bnic liquid electrode (CILE) as the working electrode. The characteristics of Hb in this modified film were investigated by scan electron microscopy, UV-Vis spectrum, FT-IR spectrum and electrochemical methods. The results showed that Hb in the film retained its native structure. A pair of well-defined and quasi-reversible cyclic voltammetric peaks appeared. Hollow CO3O4nanospheres and room temperature ionic liquids could provide a favorable mieroenvironment and enhance direct electron transfer rate. The electrochemical behaviors of Hb in the modified electrode were carefully investigated with the electrochemical parameters calculated. The Hb modified electrode showed excellent electrocatalytic behaviors to the reduction of triehloroacetie acid (TCA), and the apparent Michaelis-Menten constants (KMapp) of the sensors were calculated.3. A non-enzyme electrochemical biosensor of hydrogen peroxide (H2O2) with monodisperse C@SnO2nanoparticles synthesized by hydrothermal method was constructed on the glassy carbon electrode (GCE). A novel modified electrode was fabricated by applying C@SnO2nanoparticles and chitosan (CTS) step by step on the surface of a glassy carbon electrode (GCE). The modified electrodes (CTS/C@SnO2/GCE) were used as work electrodes ofbiological sensors, and proceed the electrochemical catalytic test for H2O2. The modified electrodes showed excellent electrocatalytic behaviors to the reduction of hydrogen peroxide. Under the optimum conditions, a linear relationship between the catalytic reduction peak currents and the concentration of hydrogen peroxide was obtained in the range from0.01to10.0mmol/L with the detection limit (S/N=3) as10.0μmol/L, respectively. |
PDF Full Text Request