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Phytic acid / gold nanoparticles, nano metal oxide - based sensing interface to build its electrochemical research

Author: WangYao
Tutor: YangHaiFeng
School: Shanghai Normal University
Course: Analytical Chemistry
Keywords: Nanomaterials Phytic acid Self-assembly Direct electron transfer Biosensor
CLC: TB383.1
Type: Master's thesis
Year: 2010
Downloads: 87
Quote: 1
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Abstract

With the rapid development of nanotechnology, its application has been extended to the field of sensors. Nano-materials with large specific surface area, high stability and good biocompatibility enzyme of the electron transfer process, and also reflect their unique catalytic effect. The phytic acid is an environment-friendly reagent, each molecule containing phosphorothioate linkages of the six non-coplanar, can occur strong complexation with the metal nano-particles or metal oxide nanoparticles. These new functional materials as a good electron transfer media to get a wide range of applications, and has attracted a number of scientific research carried out in-depth exploration of their structure, properties and applications in the field of electrochemistry. Biosensor has a very broad application prospects in the field of health safety testing, environmental monitoring and clinical medicine. And how to achieve biological molecules fixed in the converter, and also stably maintained its biological activity is to construct the biosensor most critical technologies. The purpose of this research paper is to solve this problem, the combination of nanotechnology and self-assembly technology means build electrochemical sensing interface with the the Functional Nanomaterials electrode surface, specifically the following four kinds of hydrogen peroxide biosensor development: (1) the The chapter describes a simple and effective hydrogen peroxide (H2O2) biosensor preparation. Through self-assembly technique, hemoglobin (Hb) was successfully fixed to gold nanoparticles (AuNPs) / phytic acid (PA) nanocomposite chain modified glassy carbon electrode. By UV - visible absorption spectroscopy to characterize the binding cyclic voltammetry test results show that: AuNPs play their own excellent biocompatibility and electron transport characteristics, and adsorption in the nano-chain the Hb to keep the good biological activity, and direct electron transfer. Further research shows that The biosensor good bio-catalytic activity for H2O2, the the H2O2 detection of linear range of 2.2 × 10-5 to 3.6 × 10-4 mol L-1, and a detection limit of 7.4 × 10-6 mol L-1 (signal-to-noise ratio S / N = 3). Michaelis constant (K Mapp) 1.47 mmol L-1. (2) based on the large differences will be both of the zinc oxide nanoparticles (ZnO) and hemoglobin between the isoelectric point of Hb-ZnO was prepared by mixing. Glassy carbon electrode (GCE) alternately immersed in a solution of phytic acid and Hb-ZnO layer self-assembly. The field emission scanning electron microscope (FESEM) to characterize the morphology of the multilayers on the electrode surface and to modification process characterization electrode electrochemical the chemical ac impedance spectroscopy (EIS). Further cyclic voltammetry experiments show that: embedding in the {Hb-ZnO/PA} n the composite structure of Hb achieve direct electron transfer between the electrodes but also has excellent catalytic activity for H2O2. The {Hb-ZnO/PA} 6/GCE on H2O2 short response time (less than 3 s), detect the concentration range of 2.0 × 10-6 ~ 1.2 × 10-4 mol L-1, the detection limit of 1.4 × 10 -6 mol L-1 (S / N = 3). K Mapp = 5.1 mmol L-1. (3) self-assembly of by phytate gold nanoparticles layers to form a three-dimensional ordered mesoporous Au interface at the surface of the gold electrode modified mesoporous structure and then horseradish peroxidase (HRP) to prepare a biosensor. With an atomic force microscope (AFM), and cyclic voltammetry of the process of formation of the interface of the mesoporous characterization. To hydroquinone as electronic media electron transfer between HRP and the electrode and the mesoporous membrane HRP shows excellent electrocatalytic hydrogen peroxide reduction ability. The prepared biosensors linear relationship between measured H2O2 concentration, in response to a concentration range of 6.5 × 10-6 to 1.4 × 10-5 mol L-1. Signal-to-noise ratio S / N = 3, the detection limit of 3.3 × 10-6 mol L-1. And calculate its K Mapp 0.078 mmol L-1. The sensor sensitivity and high accuracy, having a satisfactory stability and reproducibility. (4) horseradish peroxidase, gold nanoparticles and nano-titanium dioxide (TiO2) fixed on a glassy carbon electrode prepared nanocomposite film and its electrochemical properties. The field emission scanning electron microscope, electrochemical impedance and characterization of UV - visible spectral composite membranes were characterized. Experimental results show that: the special structure of TiO2 can be effectively prevented AuNPs reunion, AuNPs promote the transfer of electrons in this composite film, HRP maintained its biological activity. Cyclic voltammetry showed that the combination of TiO2 and AuNPs have a synergistic effect, not only to achieve the direct electron transfer of HRP, and also to improve the performance of this modified electrode. The composite membrane of the HRP reflects the nature of the hydrogen peroxide good catalytic reduction. Response to the current concentration of H2O2 in 6.0 × 10-5 to 1.4 × 10-4 mol L-1 a linear relationship between the detection limit is 6.5 × 10-6 mol L-1 (S / N = 3), appK M 1.2 mmol L-1. Additionally, the sensor has a longer service life and good reproducibility.

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