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1、半导体纳米材料的制备及其在生物分析中的应用 半导体纳米材料的制备及其在生物分析中的应用 【中文摘要】 半导体量子点(quantum dots,QDs)是近年来被广泛研究的一类发光物质,当其直径小于其激子玻尔直径(一般小于10 nm)时,就会表现出特殊的物理和化学性质。半导体量子点的这种特殊结构导致它具有量子尺寸效应、介电限域效应、表面效应、宏观量子隧道效应等特性,并由此派生出半导体量子点独特的发光特性。这些特性使它们在生命科学、分析科学、材料科学、免疫医学、检验检疫等传统及新兴领域中发挥着越来越重要的作用。与传统的有机荧光染料相比,量子点具有宽激发、窄发射、发射峰较窄并且对称、发射波长可通过控
2、制它的尺寸大小和组成来调节、荧光强度及稳定性是普通荧光染料的100倍左右、生物体系中几乎没有光漂白现象、生物相容性好等优点,可以用作荧光探针对生物样品和细胞进行染色。近年来在纳米技术方面所取得的研究进展使得纳米材料可以设计为高灵敏度的化学或生物传感器。纳米粒子与生物识别物质或结构相结合能够对某一特定的分析物产生响应,从而形成了纳米生物传感器。一维纳米材料(纳米棒、纳米带、纳米管以及纳米线)由于其在介观物理及纳米器件制造领域独特的应用潜力而逐步成为新的研究热点,同时一维半导体纳米材料也因本身所具有的许多独特的光学性质而获得了快速发展。理论研究比较成熟的是CdSe纳米棒,与球形半导体纳米粒子相比,
3、CdSe纳米棒的斯托克斯位移要大的多,并且在沿聚乙烯-丁烯整齐排列的长轴方向上出现极化发射现象,这对于半导体纳米棒用于生物材料标记时确定标记材料的取向很有帮助。CdSe/CdS/ZnS纳米棒作为探针用作荧光标记就要比半导体量子点亮的多。最近相继报道了很多一维半导体材料的合成,然而,合成一维纳米管却并不多见,究其原因是因为空心结构的形成条件比较苛刻。众所周知,花菁是一类可以通过改变共轭链的长度来调节吸收和发射波长的荧光染料。花菁-5是其中一个斯托克斯位移较大且发射在近红外的成员。花菁-5在600 nm左右的吸收较强,可以与CdTe量子点的发射峰位置重叠,两者相结合可以组建荧光共振能量转移体系(F
4、RET)。FRET因其对距离的敏感性,广泛地被应用于生物大分子结构、性质、反应机理以及定量分析等方面的研究。酶性DNA是近年来发展比较迅速的、与蛋白质酶和酶性RNA作用相似的酶家族新成员,另外金属离子作为辅助因子可以增强酶性DNA的活性。利用这个性质,可以通过体外选择来筛选合适的DNA链检测金属离子。本文综述了半导体量子点在生物检测中的应用、空心纳米结构的制备以及潜在的应用价值、酶性DNA作为检测金属离子探针的应用。在此基础上,分别开展了以下几方面工作:1、利用半导体纳米粒子在水油界面的自组装合成了油溶的一维CdTe纳米管和纳米线,克服了传统油相合成法的缺点。研究中分别考察了多个影响因素从而得
5、到了最优合成条件;2、设计组装了以CdTe量子点(QDs)和花菁-5(Cy-5)之间的荧光共振能量转移( FRET )为基础的纳米生物传感器:QDs- DNAzyme-Cy.5,预期目标是实现生物体内铜离子的直接测定。在没有铜离子存在的情况下,花菁-5猝灭CdTe的荧光。一旦加入铜离子后,铜离子特异性打断DNA结合位点,DNA链不可逆断开,花菁-5远离CdTe使得荧光共振能量转移现象消失,CdTe的荧光恢复从而达到测定铜离子的目的。【英文摘要】 In recent years, quantum dots have been widely investigated as a class of l
6、uminescent material. When their size is comparable to the size of Bohr diameter for exciton, they exhibit special physical and chemical properties which possess the quantum size effects, dielectric confinement effects, surface effects, macroscopic quantum tunneling effect and so on. So the quantum d
7、ots with these special optical characteristics applied in the fluorescent biological analytical applications have become a wide research focus. Compared to conventional organic dyes, QDs possess many advantages, such as narrower emission spectra, tunable maximum emission wavelength with changeable s
8、izes and compositions, photostability, high brightness, long fluorescence lifetime and biocompatibility, which have been successfully used as fluorescent probe or sensor in the imaging of biological samples and cells. Following the development on the nanotechnology, sensitive chemical and biology se
9、nsor can be designed from nanomaterial. Nanoparticles and biological material compose the nano-biological sensor which can respond to special analyte. One-dimensional (1D) nanomaterials (nanorods, nanobelts, nanotubes and nanowires) have drawn more attention particularly in view of physical and nano
10、apparatus applications. In the meantime, 1D semiconductor nanomaterials appears different optical properties, which have attracted more interest. The photoemission of CdSe nanorods is highly polarized along the longer axis and surface-modified CdSe/CdS/ZnS core/shell QRs as a biological label can be
11、 used in a variety of bioimaging applications. Furthermore, for single molecule fluorescence imaging, they are much brighter than QDs. Recently the syntheses of 1D semiconductor nanomaterial have been widely reported. However, the synthesis of 1D semiconductor nanotube was rarely researched.It is we
12、ll known that Cyanine is a kind of fluorescence dye which modulated the wavelength of abortion and emission by alter the length of conjugated chain. Cy-5 is the member of the family which has an absorption band centered at 600 nm. The fluorescence resonance energy transfer (FRET) process is highly e
13、fficient when there is an appreciable overlap between the emission spectrum of the CdTe QDs donor and the absorption spectrum of the Cy-5 acceptor. Thus,FRET is widely used for the research in molecule structures, properties, reaction mechanism and quantitative analysis. DNA was carried out catalyti
14、c functions, and thus became the newest member of the enzyme family after proteins and RNA. Metal ion as cofactor increased the active of DNAzyme. Utilizing the property, appropriate DNA chain by in-vitro selection can be used to direct metal ion.In this study, reviews were given on the application
15、of QDs in multiplexed biological detection, the synthetic methods and the potential biological application of semiconductor materials with hollow nanostructures, and the detection of metal ions by DNAzyme. On the bases of mentioned above, we carried out two aspects of investigation: 1, High aspect r
16、atio CdTe nanostructures were fabricated by hierarchical assembly of nanoparticles at the wateroil interface. The new method overcomes the disadvantages of traditional organic synthesis. In addention, we investigated the effect of several factors, including reaction temperature, reaction time, addit
17、ional components, and reactant ratio. Finally, optimal synthesis conditions have been chosed in research. 2, A new nanobiosensor QDs-DNAzyme-Cy.5 was assembled for the direct determination of copper ions (Cu2+) based on the fluorescence resonance energy transfer (FRET) between CdTe QDs and Cy.5. The
18、 sensing mechanism is based on the switching off FRET through the high specific recognition of DNAzyme to copper ions. In the absence of copper ions, Cy.5 as excellent fluorescent acceptor in CdTe-QDs-DNAzyme-Cy.5 composites. FRET switches off by the factor of copper ions-induced strand breaks in DN
19、Azyme, which restores the fluorescence of the CdTe QDs. 【中文关键词】 合成; CdTe纳米管和纳米线; 花菁-5; CdT纳米颗粒; 量子点; 荧光共振能量转移; 酶性DNA 【英文关键词】 synthesize; CdTe nanotube and nanowire; Cy-5; CdTe nanoparticle; quantum dots; FRET; DNAzyme 【毕业论文目录】摘要 5-7 Abstract 7-8 第一章 前言 9-50 1 量子点生物探针在生物检测中的应用 9-15 2 空心微米结构和纳米结构的合成和应
20、用 15-27 3 酶性DNA 检测金属离子 27-33 参考文献 33-50 第二章 CdTe 纳米管和纳米线在水油界面的分等级组装 50-75 1. 引言 50-51 2. 实验部分 51-52 3. 结果与讨论 52-57 4. 结论 57-58 参考文献 58-61 本章的英文译稿 61-75 第三章 基于CdTe 量子点和花菁-5 之间的共振能量转移监测Cu（）和Cu （）的动态转化初探 75-88 1. 引言 75-78 2. 实验部分 78-79 3. 结果和讨论 79-82 4. 阶段性结论与建议 82-83 参考文献 83-88 作者发表的学术论文及参加的课题 88-89 致谢 89