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Studies on Novel Amperometric Immunosensor and Aptasensor Based on Nano-materials

Author: GuanZuo
Tutor: YuanRuo
School: Southwestern University
Course: Analytical Chemistry
Keywords: Immunosensor Aptamer sensor Conductive polymer Carbon nanotubes Signal amplification
CLC: TP212.3
Type: Master's thesis
Year: 2010
Downloads: 133
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Abstract

The biosensor is the use of a biological activity unit (such as enzymes, antibodies, nucleic acids, cells, etc.) Physico-chemical detection elements are combined to means for detecting the analyte. Current biosensors based on before and after the current changes in the biochemical reactions to detect the concentration of biological molecules, so the increase in the current response signal, the development of high sensitivity, good stability, bio-analysis technology has been an important direction of the current type biosensor research. In recent years, the nano-materials (such as nanoparticles, nanowires, nanotubes, etc.) has been widely applied to the biosensor, which has a larger specific surface area, a good adsorption capacity and biological compatibility, etc., as the carrier of the biologically active substance which not only can increase the amount of adsorption and stability of the biological molecules, but also to maintain a good biological activity of biological molecules, and can largely improve the performance of the sensor sensitivity and life. The electrochemical immunosensor use of highly specific binding between antigen and antibody the traditional immunity test methods and modern bio-sensing technology and the electrochemical analysis technology blend, both with the immune response of high selectivity and both electrochemical analysis The high sensitivity, is widely used in the field of clinical diagnosis. Aptamer as a molecular recognition element on the fixed electrode electrochemical aptamer sensor achieved according to the electrochemical changes in the signal before and after the aptamer with the target analyte binding to the analysis device for detection of target analytes, in recent years, the development of concern. In this thesis, the nano-technology, bio-sensing technology and electrochemical analysis techniques combined analysis for immune aptamer. Application of conductive nano polymer, the gold nanoparticles, carbon nanotubes, nano-materials, nano-platinum, using different methods fixed interface to build a function of biological molecules on the electrode surface, prepared a series of excellent electrochemical biosensors. Using scanning electron microscopy (SEM), transmission electron microscopy (TEM), spectroscopy, electrochemical analysis techniques electrode assembly process, functional interface characterization and its application in the analysis of biological. Specifically, this paper carried out the following work: 1. Based polylactic 2,6 - diaminopyridine films and gold nanoparticles modified carcinoembryonic antigen immunosensor research using conductive polymer 2,6 - aminopyridine (pPA), to carcinoembryonic antigen (CEA) and carcinoembryonic antibody (anti-CEA) for the biological model molecules using electro-polymerization technology and covalent bond, and the development of new high-sensitivity current immunosensor. Simple and quick electrical polymerization method, the surface of a glassy carbon electrode (GCE) polymerization of 2,6 - diamino-pyridine (PA), created with surface-NH3 good conductive properties, structural stability, was nano-linear poly 6 - the the diaminopyridine film (pPA) immune sensor fixed matrix. This matrix using glutaraldehyde crosslinked electroactive species thionine (Thi), and re-use the the thionine molecules rich in the amino combined with a large specific surface area, strong adsorption, biocompatibility advantages of gold nanoparticles (GNPs). Then Gold Nanoparticles Immobilized carcinoembryonic antibody (anti-CEA) CEA immunosensor. After scanning electron microscopy (SEM) and other experimental characterization of the sensor of the current type immune easily create fixed polymer matrix having a mesh structure of the surface fibers can be a large increase in electrode surface area, to provide more channels for the transfer of electrons . While taking advantage of the surface thereof a large number of positively charged amino group can be preferably obtained fixed Thi, while an increase of the fixed amount of the antibody using the GNPs and preferably maintain the biological activity of the antibody. The sensor has a simple production process, low detection limit, good stability and wide linear range. Immunosensor based on gold nanoparticles and carbon nanotubes - thionine complex fixed AFP current study, multi-walled carbon nanotubes - thionine (MWNTs-Thi) complexes and gold nanoparticles fixed anti-AFP successfully constructed the highly sensitive current AFP immunosensor. In this study, on the electrode surface immobilized matrix is ??created, the choice of be regarded as linear fullerene molecule has a unique molecular structure of carbon nanotubes (MWNTs) use can with compounds containing π electrons (for example, thionine) The role of non-covalent π-π combined on the functionalized MWNTs-Thi film modified glassy carbon electrode. The fixed matrix, carbon nanotubes as a hollow tubular structure of the electrically active material thionine carrier, can improve the thionin as a mediator in the modified electrode in a fixed amount, stability, and to improve its electron transfer. MWNTs modified by thionine molecules, surface functionalization with rich amino enhance its biocompatibility, ease of further immobilized nanoparticles, biomolecules. This composite membrane by electrostatic adsorption fixed nano Kim, adsorption alpha-fetoprotein antibody, prepared an excellent current alpha-fetoprotein antigen immune sensor. The sensor production process is simple, good stability, linear range of 0.20 to 200 ng / mL, the limit of detection of 0.06ng/mL (S / N = 3). Ultrasensitive thrombin aptamer sensor built based on of nano platinum and ELISA biotin - avidin nano platinum (PtNPs,), catalase marker thrombin aptamer by hydrogen peroxide catalyzed role, build new current thrombin sensor signal amplification. This study dual aptamer sandwich analysis mode, and the enzyme-labeled catalytic amplification means. Glassy carbon electrode surface electrodepositing gold nanoparticles, can increase the electrode surface area, to improve the transmission capability of electrons between the electrode surface and the biomolecule, providing a good assembling matrix, thrombin aptamer I (TBA I) Self-assembled mercapto a fixed amount, to improve the sensitivity of detection. -Bound thrombin, will be made of containing microtiter biotin - avidin (HRP-Biotin for HRP-Adivin). Nano-platinum, thrombin aptamers II composite nano particles, the role of the thrombin aptamer fixed to the electrode surface. Labeled aptamer II PtNPs-HRP complex in the presence of hydrogen peroxide, jointly acting on the substrate, thereby generating catalytic amplified current signal. Adopted functionalized aptamer Ⅱ use PtNPs combined 5 'end-labeled thiol group of the single-chain suitable body II, and through biotin - affinity and hormone systems introduce a large number of over-oxidation of hydrogen enzyme, will PtNPs and HRP the catalytic enlarged role organic The combined amplification cycle by enzymatic catalysis and substrate, greatly increased the response current, to improve the sensitivity of the sensor. The sensor shows a strong advantage in sensitivity and of thrombin detection range of 2.3 × 10-12 ~ 1.0 × 10-9mol / L, correlation coefficient of 0.9898, the detection limit was 0.8 × 10-12mol / L.

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