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Research on the Application of Electrochemical Immunoassay for Escherichia Coli in Water

Author: LiuHuiJie
Tutor: ZhangWen
School: East China Normal University
Course: Analytical Chemistry
Keywords: E. coli Electrochemical immunoassay method Immunosensor Composite Nanoparticles
CLC: R123.1
Type: Master's thesis
Year: 2010
Downloads: 123
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Abstract

E. coli is a normal place of residence and a variety of animal gut bacteria, often excreted with the feces, widely distributed in the natural environment. Some pathogenic E. coli can cause diarrhea, dysentery, gastroenteritis, food poisoning and other diseases. Therefore, the coliform count (or coliform values) often used as drinking water and food (or drugs) hygiene standards. Japan E. coli 0157: H7 food poisoning incident in 1996, about 9,000 people poisoning economic losses. In 2000, Canada due to infection and drinking water, causing the most serious in the history of E. coli infection, resulting in more than 5,000 people infected, seven people were killed, the symptoms of E. coli infection usually in infection and 5-7 days. Harm brought against E. coli, the World Health Organization and some countries in the health sector to develop appropriate regulations, strictly limited the number of areas closely related to people's lives, such as food, domestic water and daily necessities, such as E. coli. Therefore, to establish a more agile and efficient E. coli detection of new methods to become a huge challenge for the experts in the field of clinical medicine, environmental testing and food hygiene. The traditional method of detection of E. coli multiple tube fermentation method, filter method. As one of the multi-tube fermentation method, the detection time requires at least 48 hours, and operation cumbersome, reagent consumption and other shortcomings. Therefore, the traditional method is difficult to meet the requirements for timely monitoring of the environment, food, health and other fields. Relative to traditional methods, the development of sensitive, rapid and specificity of the detection method to become an important task of the analysis of workers. Detection of E. coli of the current development of the method mainly includes: the enzyme - substrate method, molecular biology methods, immunological methods, another Matrix Assisted Laser Desorption / Ionization Mass Spectrometry, GC-MS analysis instrument can also be used for the analysis and identification of E. coli method of study. Nanomaterials having the unique catalytic properties and biological compatibility is widely used for development and has a high sensitivity, the ultra-high selectivity of electrochemical sensors. Immune method has a high specificity and selectivity, widely used in clinical diagnosis, environmental analysis, pharmaceutical analysis, food safety testing. The electrochemical method has high sensitivity, simple operation, the instrument easy to miniaturize. Therefore, we combine nanotechnology, electrochemical immunoassay technology, to achieve the detection of E. coli in Water. Our work is mainly focused on the following aspects: 1 Cu _AT_ Au composite nanoparticles labeled antibody electrochemical immunoassay method for rapid detection of E. coli in Water synthesis of Cu @ Au composite nanoparticles, and the use of the Cu @ Au The composite nanoparticles mark E. coli antibody coupled with electrochemical detection technology, proposed a new method for the rapid detection of E. coli. Cu @ Au composite nanoparticles synthesis and antibody-modified Cu @ Au composite nanoparticles were characterized by TEM. E. coli immobilized on polystyrene modified ITO conductive glass (ITO), Cu _AT_ Au composite nanoparticles labeled antibody immune response to identify E. coli immobilized on ITO. Oxidation method Cu @ Au composite nanoparticles of copper in the form of ions dissolved mercury film / Nafion modified glassy carbon electrode as the working electrode, anodic stripping method to detect the release of copper ions. Use of the modified electrode to detect copper ions, the detection limit of 9.0x10-12mol / L can be achieved. Since Cu _AT_ Au composite nano particles-labeled antibody is only specific combination with E. coli, so the use of the copper ion concentration to the concentration of E. coli can be indirectly detected. The detection limit of this method can be as low as 30 cfu / mL. The entire detection process requires only two hours that can be completed. 3 cfu/10 mL of E. coli can be detected to surface water through enrichment was concentrated using the electrochemical detection method. Fe3O4 @ Au composite nanoparticles labeled antibody electrochemical immunoassay method for the detection of E. coli in Water of synthetic Fe3O4 _AT_ Au composite nanoparticles as a carrier of horseradish peroxidase labeled antibody, and the composite nanoparticles marker applications amplified in an electrochemical immunoassay. The electron mediator thionine polymer in a glassy carbon electrode surface, gold nanoparticles as the base of fixed E. coli antibodies to measure the current signal generated by horseradish peroxidase-catalyzed solution H202 E. coli. Experimental results show that: the linear range of the method for detection of E. coli in Water for 50 ~ 105cfu/mL, and the detection limit of 20 cfu / mL. Actual water samples after enrichment after the detection sensitivity of E. coli in Water reaches 2 cfu / mL. Studying this part 3 of gold nanoparticles and the poly anthranilic acid-based biosensor for detection of E. coli in water was prepared by a novel ampere sensor and used for the detection of E. coli in water. Glassy carbon electrode substrate, the deposition of gold nanoparticles on the electrode surface, the surface of the gold nanoparticles (Au NPs) electrically polymerizable poly anthranilic acid (poly-o-ABA) to provide rich carboxy prepared stable sensor interface in fixed immunologically reactive substance. Formed poly-o-ABA/Au NPs with SEM and FTIR. Through cooperation with fixed coli antibody by a covalent bond to the sensor interface. On hydroquinone body for the electronic media catalyzed H202 reduction current typical sandwich reaction, horseradish peroxidase, sensitive and specific detection of E. coli can be achieved. Examine H202 concentration, immune reaction conditions for the cultivation time, pH and other factors on the catalytic current. Under optimal conditions, the method can detect the concentration range of 103 ~ 107 cfu / mL E. coli. The successful detection of E. coli in the river.

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