Study On The Synthesis Of Silver Nano-materials And Their Application In Electrochemical Sensors

Due to the advantages such as good accuracy, fast analysis, high sensitivity and simple detection process, electrochemical sensors have important application potentials in the food analysis, pharmaceutical and clinical detection fields. Nanomaterials have become hot spot in the fabrication of electrochemical sensors with the rapid progress in nanotechnology. Based on the good conductive ability, silver nanomaterials have caught attention more and more widely. Thus, the main content of this thesis is the preparation of several silver nanomaterials and their application in electrochemical sensors to detect glucose, chiral amino acid and hydrogen peroxide.1. Different morphology of nanomaterials including gold-silver nanotubes, silver nanocubes, silver nanoparticles and copper oxide nanowires was preparated. Gold-silver nanotubes, silver nanocubes, and silver nanoparticles were obtained by polyhydric alcohol reduction method. Copper oxide nanowires were prepared by wet chemical method. Their morphology was uniform, with a diameter of100run. The morphology structure of these nanomaterials was characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray powder diffraction (XRD).2. A bienzyme glucose sensor was built based on AgNCs and Gox-HRP. Atomic force microscope (AFM) and cyclic voltammetry (CV) were employed to characterize the constructing process of the modified electrode. The mechanism of biosensor for glucose detection was verified by CV characterization. AgNCs and HRP played the role of the dual amplification signal. Under optimized conditions, the electrode modified with AgNTs-CS-Gox-HRP could detect glucose in the linear range of10μmol L-1～1.5mmol L-1, with the detection limit of0.698μmol L-1(S/N=3). The glucose biosensors showed high sensitivity and good stability.3. The electrochemical chiral sensor was constructed based on composite nanomaterials of P-CD-S-AgNWs and could recognize the chiral phenylalanine (Phe). Transmission electron microscopy (TEM) characterized the morphology of β-CD-S-AgNWs. Differential pulse voltammetry (DPV) characterization proved the mechanism of the modified electrodes for detection of L-Phe. By optimizing the ratio of AgNWs and β-CD, reaction time and so on, the sensor coule detect L-Phe in the linear range of0.5～12mmol L-1, with the detection limit of0.024μmol L-1.4. In order to explore the relationship between the morphology and electric catalytic activity of nanomaterials, we preparated Au-AgNTs/CS, AgNCs/CS, AgNPs/CS and CuONWs/CS composites membranes modified electrodes to detect H2O2. The electrochemical properties of modified electrodes were characterizated by CV. Then the working potential, pH and the quantity of the nanocomposites were optimized. Under the optimized condition, the constructed electrodes could detect hydrogen peroxide rapidly and sensitively. Among them, Au-AgNTs/CS modified electrodes could detect H2O2in the linear range of8μmol L-1～1.3mmol L-1, with the detection limit of3.18μmol L-1(S/N=3); AgNPs/CS modified electrodes could detect H2O2in the linear range of8μmol L-1～1.75mmol L-1, with the detection limit of0.066μmol L-1(S/N=3); CuONWs/CS modified electrodes could detect H2O2in the linear range of8μmol L-1～0.654mmol L-1, with the detection limit of7.42μmol L-1(S/N=3). In conclusion, Au-AgNTs and CuONWs conductive ability is weaker compared to the silver nano-materials. And the smaller the particle, conductive ability will be better and the detection limit will be lower.