| In recent work,it has been discovered that materials in nano-size scale (1～100nm)display size-dependent optical,magnetic,electronic and chemical properties.Except these,nanomaterials have unknown chemical and physical properties that 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 can largely improve electrical responses and the detection sensitivity.Today,many novel nanostructured materials have been applied in electroanalytical chemistry and some important progresses along these topics have recently achieved.Biomacromolecula including proteins and enzymes are the primary groups of life. They are involved in metabolism and other important physiological processes,which are characteristics of electron transter between their oxidation and reduction states. Therefore,to study the process of life is to investigate the electron transmittion in essence.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 electode can establish a foundation for fabricating new kinds of mediator-free biosensors,biofuel cells,bio-reactors.The nanostructured materials can greatly enhance the active surface available for protein binding over the geometrical area,and maintain the proteins' physiological activity without detectable denaturation.This dissertation research focuses on developing modified electrodes based on nanostructrued materials,which is one of most active areas in electroanalytical chemisty of proteins.We are adhering to an organic combination of electoanalytical chemistry,nanotechnology and proteins chemistry.Of course,it is a new area worthy of attention and it is also helpful to set up new methods,new techniques and new theories.The details are given as follows:1.Electeochemistry and Electrocatalytic Properties of Hemoglobin in Layer-by-Layer Films of SiO2 with Vapor-Surface Sol-Gel Deposition(Chapter 2)Layer-by-layer {Hb/SiO2}n films assembled by alternate adsorption of positively charged hemoglobin(Hb)and vapor-surface sol-gel deposition of silica at 50℃onto a glassy carbon electrode were reported.The result films were characterized with cyclic voltametery,electrochemical impedance spectroscopy,UV-vis spectroscopy,and SEM, and the direct electrochemical and electrocatalytic properties of Hb in these layer-by-layer films were investigated.A pair of well-defined quasireversible cyclic voltammetric peaks were observed,and the formal potential of the heme FeⅢ/FeⅡredox couple was found to be -0.330V(vs SCE).The electron-transfer behavior of Hb in {Hb/SiO2}n films was dependent on the vapor temperature,the number of layers, and the pH of the Hb solution,based on which a set of optimized conditions for film fabrication was inferred.The hemoglobin in{Hb/SiO2}n films displayed good electrocatalytic activity to the reduction of hydrogen peroxide,and H2O2 had linear current response from 1.0×l0-6to 2.0×l0-4mol/L with a detection limit of 5.0×10-7 mol/L(S/N=3).The apparent heterogeneous electron-transfer rate constant(ks)was 1.02±0.03s-1,and the apparent Michaeli-Menten constant(Kmapp)was 0.155 mmol/L, indicating a potential application in the third-generation biosensor.2.Direct electron transfer and electrocatalysis of hemoglobin in layer-by-layer films assembled with Al-MSU-S particles(Chapter 3)In this paper,layer-by-layer(LBL){MSU/Hb}n/PDDA films assembled by alternate adsorption of positively charged hemoglobin(Hb)and negatively charged mesoporous molecular sieves of Al-MSU-S onto a glassy carbon electrode(GCE) were reported.Al-MSU-S was synthesized by the precursor of zeolite Y and ionic liquids 1-hexadecane-3-methylimidazolium bromide(CMIMB)as a template in basic medium.It exhibited larger pore diameter,pore volume and surface area.Direct electrochemical and electrocatalytic properties of Hb in these layer-by-layer films were investigated.A pair of well-defined nearly reversible cyclic voltammetric peaks was observed and the formal potential of the heme FeⅢ/FeⅡredox couple was found to be -0.295V(vs.SCE).The influences of layer's number and the pH of the external solution to the electron transfer behavior of Hb in {MSU/I-Ib}n/PDDA films were also estimated by cyclic voltammetry and a set of optimized conditions for film fabrication was inferred.The hemoglobin in{MSU/Hb}n/PDDA films displayed a good electrocatalytic activity to the reduction of hydrogen peroxide,which had linear current responses from 1.0×10-6to 1.86x10-4mol/L with the detection limit of 5.0×10-7mol/L(S/N=3).The apparent Michaeli-Menten constant(Kmapp)was 0.368 mmol/L.Thus,this methodology shows potential application of the preparation of third-generation biosensors.3.The Electrochemical Property of Hb/HGN/CHIT Modified Glassy Carbon Electrode and its Application as Biosensor(Chapter 4)Hollow gold nanospheres(HGN)with uniform diameter have been synthesized by sacrificial glavanic replacement of cobalt nanoparticles.Electrochemical and electrocatalytic properties of Hb in Hb/HGN/CHIT film were investigated.A pair of well-defined nearly reversible cyclic voltammetric peaks was observed and the formal potential of the heme FeⅢ/FeⅡredox couple was found to be -0.342V(vs.SCE).The influences of scan rate and the pH of the external solution to the electron transfer behavior of Hb in Hb/HGN/CHIT films were also estimated by cyclic voltammetry. The hemoglobin in Hb/HGN/CHIT films displayed a good electrocatalytic activity to the reduction of hydrogen peroxide,which had linear current responses from 1.0×10-5 to 1.5×10-4amol/L with the detection limit of 5.0×10-6mol/L(S/N=3).The apparent Michaeli-Menten constant(Kmapp)was 0.388 mmol/L.
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