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Quantum Dot Modified with Gemini Surfactant for Selective Recognition of Protein

Author: HuMengYao
Tutor: SongGongWu
School: Hubei University
Course: Analytical Chemistry
Keywords: luminescent nanomaterial quantum dots Gemini surfactant protein detection Fluorescence spectra
CLC: O629.73
Type: Master's thesis
Year: 2012
Downloads: 19
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Abstract


Semiconductor nanocrystals (NCs) whose radii are smaller than the bulk exciton Bohr radius constitute a class of materials intermediate between molecular and bulk forms of matter. Quantum confinement of both electron and hole in all three dimensions (so called quantum dots) leads to an increase in the effective band gap of the material with decrease of NCs size. Consequently, Cadmium chalcogenide NCs exhibit all efficient photoluminescence(PL), and their energy or color can be controlled easily by adjusting their sizes. Because the surface of a nanocrystal is made up of atoms that are not fully coordinated, it is highly active and invites the possibility of epitaxial overgrowth of another semiconductor material In addition, surface atoms act like defects before passivated. To remove these defects, high quality homogeneous and monodisperse NCs have been passivated with the layer of inorganic epitaxial growth This call not only eliminate both the anionic and cationic surface dangling bonds but also generate a oew nanocrystal system with novel properties.Semiconductor quantum dots (QDs) have attracted great interest during the last two decadades due to their unique optiacl and photochemical stability, giving rise to numerous potenial applications in chemistry, physics, biology and medicine. For routine preparation, the available high-quality QDs are not well in Biological compatibility which are not suitable for biological application. Thus, these semiconductor quantum dots have to be furthermodified to allow to detect the biomolecules. My dissertation is foucused on the preparation, modification and primary application of high quality fluorescence quantum dots. Now, some new result are obtaind from our expertments.1. The interaction of the cationic Gemini surfactant hexamethylene-1,3-bis (tetradecyldimethylammonium bromide)(G14-6-14) with bovine serum albumin (BSA) has been investigated by fluorescence quenching spectra and three-dimensional (3D) fluorescence spectra. The Stern-Volmer quenching constants Ksv and the corresponding thermodynamic parameters ΔH, ΔG and ΔS have been estimated by the fluorescence quenching method. The results indicated that hydrophobic forces were the predominant intermolecular forces between BSA and the surfactant. Competitive experiments and the number of binding sites calculation show that G14-6-14can be inserted in site-II (in subdomain IIIA) of BSA. The effect of G14-6-14on the conformationof BSA was evaluated by synchronous fluorescence spectroscopy and3D fluorescence spectral methods. The results show that the conformation of BSA was changed dramatically in the presence of G14-6-14, by binding to the Trp and Try residues of BSA. The investigation provides interaction between BSA and G14-6-14as a model for molecular design and industrial research.2. Surfactant as a micromolecule to modify QDs, investigate their interaction. CdTe-G14-3-14as a fluorescence probe to investigate the fluorescence quenching of BSA to QDs. In this paper, we employed fluorescence correlation spectroscopy (FCS) to investigate the nonspecific interaction between CdTe-G14-3-14and bovine serum albumin (BSA) as a model. An excitation wavelength of350nm was selected and the fluorescence spectra were recorded in the range of500-680nm.The width of the excitation and emission slits was set at4.0nm and4.0nm, respectively. An excitation wavelength of350nm was chosen and the emission wavelength was recorded from500to680nm. The results showed that the fluorescence intensity of the CdTe-G14-3-14gradually enhanced with increasing the concentration of BSA, which is because of formation of core-shell structure. Therefore, in this paper we also had investigated the affection of some other interferingion to BSA, and the detection limit of each interferingion is, respectively. Last, we had based on the actual samples by the QDs presented, the LOD result of the urine is0.18μgL3. ZnSe QDs with short wave length-fluorescence were prepared in aqueous solution with3-Mercaptopropionic acid (MPA) as capping reagent. And ZnSe dots on the synthesis conditions were systematically studied. Characterized by TEM and XRD morphology characteristics and crystal structure of ZnSe Qdots. The results show that ZnSe nanoparticles have good stability, high fluorescence intensity and good adjustable emission spectra of ZnSe, ZnSe dots by Surfactant with the G16-6-16assembly and other means, We can get what we need of the CdTe-G14-3-14synthesized fluorescent material. Meanwhile based on the presence of proteins,the fluorescence intensity of CdTe-G14-3-14nanoparticles significantly reduce this phenomenon,established a kind of CdTe-G14-3-14for the fluorescence probe method for determination of bovine serum albumin, Under optimal conditions, the linear range was AF=0.41+0.081CBSA(μg L-1). Detection limits were LOD=2.66μg L-1. And samples were determined with satisfactory results.

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CLC: > Mathematical sciences and chemical > Chemistry > Organic Chemistry > Natural compounds > α-amino acids,peptides, proteins, nucleic acids > Protein
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