单分子三维取向研究
文献类型：学位论文
| 作者 | 王金媛 |
| 学位类别 | 硕士 |
| 答辩日期 | 2007 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 刘力 |
| 关键词 | 三维取向 荧光单分子 偏振 全内反射 离焦成像 |
| 其他题名 | Three-Dimensional Orientations of Single Molecules |
| 中文摘要 | 随着科学技术的不断向前发展，人们对世界的认知也不断加深，大到宇宙太空，小到纳米世界都引起了人们极大的研究兴趣。上个世纪八十年代，扫描隧道显微镜（scanning tunneling microscope, STM）的出现使单分子探测不再是梦想。自此以后，单分子研究引起了广泛的关注，人们力图在单分子水平来重新解读各种生命现象，揭示被系综平均所掩盖的各种局部效应。活体中研究单分子，首先选用光学技术，这是因为光子对受研究的分子扰乱最轻微，因此结果最直接和可靠。光学技术中，荧光因为它的高检测灵敏度常被选用。因此，荧光单分子也成为人们研究的一个热点。 单分子取向作为荧光单分子的一个重要特性，对其研究也具有十分重要的意义：1.单分子的许多光学特性都与它的方向有关；2.确定偶极矩方向是用荧光共振能量转移来更精确地探测分子间距离的先决条件；3.它可以成为研究分子与周围环境，分子与分子间相互作用的超灵敏探针；4.生物大分子的构象状态及其变化的动力学过程可以由单分子取向的改变来确定。因此单分子三维取向也成为目前的一个重要研究对象。 本论文围绕着荧光单分子及单分子的三维取向主要做了两个方面的工作，第一部分对不同单分子的荧光发光时间和发射功率等特性进行了分析和比较；第二部分对荧光标记物的三维取向进行了理论方面的模拟和分析，同时进行了实验方面的研究。本文主要取得了以下几个方面的创新性进展： 1.荧光单分子特性研究。用全内反射的显微方式来激发体外的荧光素和绿色荧光蛋白（GFP），对两者的发光持续时间和发射的峰值功率进行了统计分析，并比较了两者的差别。计算了光漂白前，两者发射的总的光子数，比较了它们的光稳定性。 2.单分子三维取向的理论研究。模拟了全内反射下由隐失场激发的单个分子的荧光在离焦的情况下，探测面上的光强分布，并由此改进了单分子三维取向的探测方法。改进后的方法可以进行真正的三维取向探测。 3.量子点三维取向探测。对荧光单分子（1D）的三维取向理论和量子点(2D)的三维取向进行了比较。在实验中，首次采用通过偏振的全内反射隐失场和远场传输场分别激发量子点，根据荧光强度的不同成功得到了量子点的三维取向。 |
| 英文摘要 | With the science and technology developed forward, people have been deepened understanding of the world. From universe outer space to the nanometer world all arouse people's research interests. 80's last century, the appearance of scanning tunneling microscope (STM) made the research of single molecules was not a dream. Ever since, the studies of single molecules are having aroused broad attention. People strive to understand and explain various biological phenomena in the level of single molecules, to explore various part effect that had been buried in the average properties of a system. Studies of the single molecules in the living cells, optical technology should be selected and used first, because molecules are disturbed by the photon slightest than others, results are direct and reliable. In the optical technology, fluorescence is often selected and used because of its supreme sensitiveness. Therefore, the study about fluorescence single molecules also becomes a hot spot that people study. The three-dimensional orientation which is an important characteristic property of single molecules, also has very important significance to study. 1. Many optics characteristic properties of single molecules are connected with its direction; 2. Ascertaining dipole direction is the precondition to detect the distance between molecules by forster resonance energy transfer (FRET); 3. It can make single molecules become a probe to study the interacting of individual molecules and the interacting of molecules and surrounding nanoenvironment; 4. The change of big molecule’s structure can be confirmed by the change of the single molecules orientation. Therefore, three-dimensional molecule orientation studies become a hotspot. We give a general review on current researches and detection of single molecules and the orientation. Our work included two parts. The first part is the experiments of GFP and fluorescein. We compared the intensity and duration between them, calculated the photon number before photobleaching. The second part is simulation and analysis in theory about the three-dimensional orientation of single molecules, and we also have carried out experiment about quantum dots. The main innovations are as following: 1.The research about the characteristic of single molecules. Single GFP and fluorescein molecules were excitated by total internal reflection (TIR). The reciprocal of duration and exciting intensity was obtained, the photon number that they launched before photobleaching were calculated, the photostability of them were compared. 2.The theory about the three-dimensional orientation of single molecules. The different field distribution under defocused imaging was simulated, and we improved the method of detecting three-dimensional orientation of single molecules. The improved method could get the real three-dimensional orientation. 3.The three-dimensional orientation of single quantum dots. Compared the theory of orientation about 2D transition dipole and 1D transition dipole. In the experiment, the single quantum dots orientation was obtained by comparing fluorescence intensities measured with ei-fluorescence imaging scheme and TIP imaging scheme. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16533]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 王金媛. 单分子三维取向研究[D]. 中国科学院上海光学精密机械研究所. 2007. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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