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Sensors based on gold nanoparticles and their composite system research

Author: LiMengYao
Tutor: HuangShanSheng
School: Shanghai Normal University
Course: Analytical Chemistry
Keywords: Gold nanoparticles and gold nanoparticles - chitosan composite Sensor Layer-by-layer assembly technique Determine
CLC: O657.1
Type: Master's thesis
Year: 2009
Downloads: 165
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Abstract

With the rapid development of science and technology, people are increasingly concerned about their own health as well as the quality of the living environment. But for some patients caused by defects in DNA fragments, or because of certain substances in the environment, excessive pollution caused, it is hard, or that existing detection methods such as defects, which difficult to early detect them, so as to achieve the object of the governance. So simple, research and development, high sensitivity, high selectivity detection technology for people's health and environmental safety have significant and far-reaching significance. In recent years, due to the properties of nanomaterials, especially gold nanoparticles, because of its excellent electrical conductivity properties, huge specific surface area, good biological compatibility has been widely applied to the study of the various types of biosensors and preparation process, and more and more people pay attention. The gold nanoparticles can be used as the fine conductive center to promote the electron transfer in the electrochemical reaction, to improve the sensitivity of the response, the amplification response signal, certain substances can also generate unique electrochemical response. In addition, gold nanoparticles can serve as a fixed vector of certain proteins, which direct electrochemical behavior of the protein on the electrode. There is no doubt that the gold nanoparticles has broad application prospects in the field of electrochemical biosensors. This thesis will combine layers of self-assembly technology and nanotechnology, and applied to the electrochemical biosensor. Research ideas: (1) gold nanoparticles have good biological compatibility, as well as to promote the effectiveness of electron transport, as carrier material, developed electrochemical biosensor with higher sensitivity and greater response signal; (2) nano gold particles and other material layers assembled system in electrochemical sensors and sensor response mechanism research. This thesis mainly include the following: gold nanoparticles and gold nanoparticles - Preparation of chitosan composites, characterization of gold chloride acid and tri-sodium citrate as raw material, the use of chemical reduction was prepared particle size is more uniform spherical or spherical gold nanoparticles; chitosan solution mixed prepared gold - chitosan complex. UV-visible absorption spectroscopy and transmission electron microscopy to characterize the gold nanoparticles and gold nanoparticles - chitosan complex. Modified them to the electrode surface in the process of the modified electrode, the method of using self-assembled, so as to achieve to promote electron transfer, the purpose of increasing the response signal or the like. 2 DNA biosensor based on ssDNA / Cyt c / L-Cys / GNPs / Chits modified glassy carbon electrode technology, using layers of modified chitosan, gold nanoparticles, L-cysteine, cytochrome c and ssDNA probe to the modification to the surface of the glassy carbon electrode was prepared by a novel DNA biosensor. Respectively voltammetry, impedance spectra, etc., it is characterized by an atomic force microscope to observe the morphological differences between the different layers of the DNA biosensor. The results showed that the modified electrode in 0.120V and 0.362V appear symmetrical peak shape redox peaks the adsorbed ssDNA probe is 1.672 × 10 ^{-10 mol cm ^{-2 . Help indicator daunorubicin, can be used for hybridization with DNA probes complementary DNA, so as to achieve the purpose of the determination of DNA. 3 the based on Electrodeposition of Prussian blue, the self-assembly of carbon nanotubes, gold nanoparticles - chitosan composite H ₂ O ₂ sensor by self-assembly of multi-walled carbon nanotubes gold nanoparticles - chitosan complex electrical deposition of Prussian blue prepared a new H ₂ O ₂ sensor. The H ₂ O ₂ sensor in 0.1 M KCl solution, two obvious peaks appear at 0.101 V and 0.193 V, corresponds to Prussian blue and Prussian white conversion. H ₂ O ₂ concentration of 3.98 ~ 19.61μM and 27.27 ~ 42.15μM range in response to the current into a good linear relationship, the regression equation for the I _p = 0.034c (H ₂ O ₂) 0.026 (R ₁ = 0.9948) and I _{p < / sub> = 0.028c (H ₂ O ₂) 0.274 (R ₂ = 0.9922), with a detection limit of 3.36μM (3 times the signal-to-noise ratio). 4 modified of cytochrome c L-Cys/Au electrode for nitrite ion detection using cyclic voltammetry, AC impedance studies assembled in the L-cysteine ??modified gold electrodes on the electrochemical behavior of cytochrome c; using electrochemical method and UV - visible spectroscopy to characterize the electrode. The results show that: assembled by electrostatic adsorption of cytochrome c on a gold electrode modified L-Cys good biological and electrochemical activity Cyt c / L-Cys-modified gold electrode detection of nitrite, in response to the current and nitrite root concentration of 5.0 × 10 ^{-6 to of 4.5 × ^{-4 M within a linear relationship between the linear regression equation was I _p = 0.031c (NO ₂ ^{- ) 8.165 × 10 ^{-6 , a correlation coefficient of 0.9995, the detection limit of 1.5 × 10 ^{-7 (three times the signal-to-noise ratio). For analog samples and pickles samples Nitrite determination, the recovery rate of 89.0% to 116.0%.}}}}}}}}

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