Preparation Of Carbon Nitride Quantum Dots/Bimetallic Organic Framework Three-Dimensional Composite And Its Application As Artificial Peroxidases

Bio-enzyme is a polymer compound with biocatalytic function.As a natural biocatalyst,it has the advantages of high catalytic efficiency and specificity.Due to the complex structure,poor environmental resistance and high price,its application has been limited.Therefore,it is necessary to study synthetic materials with bio-enzymatic properties.In recent years,the metal organic framework,as a new type of ordered porous crystal,has attracted wide attention due to its inherent properties such as high specific surface area,structural diversity,and trimmability.In this thesis,g-C3Nx/ZIF-8(Cu-Zn)was used as an artificial enzyme to establish a new method for sensitively determining the concentration of glucose in serum.In chapter one,the biomimetic enzyme materials and biological enzymes were briefly introduced,the significance of the development of artificial enzyme materials was clarified,and several common methods for the synthesis of artificial enzymes were outlined.Then the research background,synthesis methods and important applications of metal-organic framework materials were introduced.Finally,the research purpose and design ideas of this work were proposed.In chapter two,we prepared and characterized g-C3Nx/ZIF-8(Cu-Zn)composites.Bulk g-C3Nx was prepared by the thermal polymerization of melamine with a strong alkali,and the obtained g-C3Nx was ultrasonically stripped in a mixed solution of concentrated sulfuric acid and concentrated nitric acid.Then the prepared g-C3Nx quantum dots were wrapped in ZIF-8(Cu-Zn)to obtain g-C3Nx/ZIF-8(Cu-Zn).The metal-organic framework was characterized by infrared spectroscopy,transmission electron microscopy,X-ray diffraction,X-ray electron spectroscopy and Brunner-Emmet-Teller(BET)measurements.In chapter three,the peroxidase activity of g-C3Nx/ZIF-8(Cu-Zn)was studied by selective catalytic oxidation of 3,3’,5,5’-tetramethylbenzidine.Its catalytic behavior is in accordance with the Michaelis-Menten catalytic kinetics model.The catalytic kinetic constants of hydrogen peroxide and 3,3’,5,5’-tetramethylbenzidine were calculated as 0.0176 mM and 0.222 mM,respectively.The maximum catalytic reaction rates of the two substrates were 1.59× 10-7 Ms-1 and 3.54 × 10-7 Ms-1,respectively.Based on the outstanding peroxidase activity of g-C3Nx/ZIF-8(Cu-Zn),the concentration of H2O2 could be detected sensitively.Glucose could produce H2O2 under the catalysis of glucose oxidase.Thus,a new method for detecting the concentration of glucose in serum was established.Compared with hospital test results,the results obtained using the proposed method was proved to be accurate.In chapter four,the preparation method of g-C3Nx/ZIF-8(Cu-Zn)composites and the detection method with g-C3Nx/ZIF-8(Cu-Zn)as catalyst were summarized and prospected.