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Organic-inorganic hybrid materials and nanomaterials immobilized enzyme electrochemical biosensors

Author: TanShengWei
Tutor: TanXueCai
School: Guangxi University for Nationalities
Course: Applied Chemistry
Keywords: Organic - inorganic hybrid materials Multi-walled carbon nanotubes Nano- copper Zinc oxide nanoparticles Biosensor Glucose oxidase Hemoglobin Horseradish peroxidase
CLC: TP212.3
Type: Master's thesis
Year: 2011
Downloads: 85
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Abstract


Electrochemical biosensor is today the analytical chemistry and sensor technology and measurement science important research, mainly used in environmental monitoring, biomedical, food analysis and other fields. Sensing material and enzyme sense membrane construction method is to develop excellent electrochemical biosensor key. Based on sol-gel method of organic - inorganic hybrid materials have different from other material benefits for biological molecules fixed terms, as an ideal material. In this thesis, organic - inorganic hybrid materials have been synthesized by a sol-gel method, and then for a fixed hemoglobin, horseradish peroxidase, glucose oxidase developed a new biosensor. Study its electrochemical properties, the establishment of analytical methods, investigating the law and so on. This thesis consists of the following components: Preparation of a novel sol - gel organic - inorganic hybrid materials (PVA / TiO 2 ) embedding multi-walled carbon nanotubes and hemoglobin hydrogen peroxide biosensor . By electrochemical experimental results show that embedded in the hybrid material within the hemoglobin original biocatalytic activity is retained; addition, the multi-walled carbon nanotubes enhance the hydrogen peroxide catalytic properties, and promote the electron transport. Study of various factors such as concentration of the electrolyte, pH, enzyme concentration on the sensor response current, the sensor hydrogen peroxide linear response range of 5.0 × 10 -7 mol / L ~ 2.7 × 1.0 -6 mol / L (correlation coefficient of 0.997), the detection limit of 1.0 × 10 -7 mol / L (S / N = 3), the measured hemoglobin (Hb) catalyst Kinetic Parameters The Michaelis constant (Km) = 0.997 × 10 -6 mol / L. Biosensor with good repeatability, selectivity, high sensitivity and long term stability. A novel organic - inorganic hybrid materials, this hybrid material is composed of titanium dioxide sol and chitosan composition, this hybrid material to overcome the ordinary sol - gel easy to brittle fracture characteristics, can be effectively retained by embedding The Hb biocatalytic activity; and multi-walled carbon nanotubes and nano Cu synergistic effect improves the hydrogen peroxide catalytic performance and facilitate the electron transfer. Studies of various factors on the sensor response current. Hydrogen peroxide response linear range 1.0 × 10 -7 mol / L ~ 1.35 × 10-4 mol / L, the correlation coefficient 0.997, detection limit 1.0 × 10 -8 mol / L (S / N = 3), the apparent Michaelis constant Km = 12.83 × 10 -6 mol / L. Preparation of a highly sensitive biological compound bienzyme biological glucose sensor through embedding glucose oxidase (GOx) and horseradish peroxidase (HRP) in poly (vinyl alcohol) / titania hybrid materials, the will be fixed in a multi- walled carbon nanotubes and nano-copper-modified glassy carbon electrode. Such hybrid materials can retain entrapped HRP biological activity. In addition, multi-walled carbon nanotubes and copper nanoparticles synergy enhances glucose catalytic performance, promote glucose electron transfer. Bio-composite membrane electro-catalytic activity of the sensor for glucose detection response linear range 6.2 × 10 -8 mol / L 1 .0 × 10 -6 mol / L (linear regression coefficient 0.998) and the detection limit of 1.0 × 10 -9 mol / L (S / N = 3 pm). The apparent Michaelis constant (Km) of 3.7 × 10 -8 mol / L, and high sensitivity, selectivity and good reproducibility and long-term stability. Based on Hydrothermal Microemulsion Synthesis of ZnO nanorods and the hemoglobin dispersed in polyvinyl alcohol and zinc oxide nanorods hybrid composite membranes were prepared and efficient hydrogen peroxide sensor. Biocompatible ZnO-PVA composite membrane hemoglobin provides a suitable microenvironment make biological activity remains (Michaelis constant 0.0019 × 10 -6 mol / L). Electrochemical properties, the pH and the concentration of hemoglobin was also studied, Hb-ZnO/PVA sensor for hydrogen peroxide detection exhibit very good analytical performance, the linear range of 1.0 × 10 -8 mol / L 3 .2 × 10 -6 mol / L, detection limit of 0.009 × 10 -6 mol / L (S / N = 3 ) and sensor stability, reproducibility is very good. Developed using Nafion dispersion carboxyl multi-walled carbon nanotubes chemically modified electrode (GCE/Nafion- MWCNTs), study 2, 4 - two nitro-1 - naphthol (2, 4-dinitro-1-naphthol) in modified electrode electrochemical behavior and determination methods. Experimental results show that in 0.025 mol / L Michaelis (pH 6.7) solution, the modified electrode 2, 4 - two nitro-1 - naphthol has obvious catalytic and sensitizing effect of the reduction peak potential changes from -0.710 V (bare electrode) is moved to -0.370 V (vs.AgCl / Ag) (modified electrode), the peak potential shifted 340 mV, the sensitivity increased by about three times, and the reduction current increased significantly. The various experimental conditions were optimized to obtain a quantitative determination of 2, 4 - nitro - 1 - naphthol linear range of 1.0 × 10 -8 mol / L 2 .0 × 10 -5 mol / L, ip / (μA) = 2.248 0.87c (10 -6 mol / L), the correlation coefficient R of 0.998, the detection limit of 1.0 × 10 -9 mol / L. Of 2, 4 - two nitro-1 - naphthol were determined, recoveries 97.1% 1 01.3% between.

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