【作者】 陈伟；

【导师】 张国庆；

【作者基本信息】 中国科学技术大学 ， 高分子化学与物理， 2016， 硕士

【摘要】 能量转移体系和超分辨荧光显微成像是当今两大研究热点,前者有助于我们理解自然界中的光合作用的能量吸收与转移,后者可以方便的、无损的研究生物样品,尤其是对细胞内的精细结构和细胞内的相互作用的研究有着极其重要的意义。本文希望通过合成罗丹明衍生物,对能量转移体系和超分辨荧光显微成像进行探究,并能够理解其内在机理。本文的第一章主要是相关背景知识和理论基础,主要分为两大部分,荧光原理和超分辨荧光显微成像背景知识。荧光原理部分包括：激发与发射、能量转移、激子、荧光寿命与量子产率、稳态与时间分辨荧光光谱和荧光光谱仪。其中,能量转移部分又分为荧光共振能量转移(fluorescence resonance energy transfer, FRET)和电子交换能量转移；激子部分又分为Frekel激子和Wannier-Mott激子。超分辨荧光显微成像部分包括：衍射极限和超分辨荧光显微成像技术。其中,超分辨荧光显微成像技术主要介绍了受激发射耗损技术(stimulated emission depletion, STED)、结构光照明显微镜技(structured illumination microscopy, SIM)、光激活定位显微镜技术(photo-activation localization microscopy,PALM)与随机光学重构显微镜技术(stochastic optical reconstruction microscopy, STORM)。本文的第二章中,我们设计了由重复的染料分子单元二氟化硼二苯甲酰甲烷(BF2dbm)和一个封端的罗丹明B分子(RhB)所组成的荧光聚合物,其由于长寿命的聚合物激子而展现出高效的能量转移(EnT)。外部刺激,例如溶剂化作用和温度,能影响到能量转移的效率,从而改变发射光的波长。对供体-受体聚合物的理论计算和超快激光光谱研究揭示了在稀溶液中分子内的BF2dbm聚集体导致了更加禁阻和几乎退化的单线态和三线态。因此这些聚集体在光激发后充当了激子储存库,这使得受体RhB更容易接受能量,从而使得所观测的能量转移更加高效。这个无金属原子的模型系统通过长寿命的激发态实现了非常高效的能量转移。本文的第三章中,我们利用简单的酯化反应(DMAP和EDC·HCl作为催化剂)可以很简单地得到一系列罗丹明B与甲基封端的不同单元数的聚乙二醇的衍生物(RhB-4PEG,RhB-7PEG,RhB-10PEG,RhB-22PEG)。罗丹明B分子的光漂白速度很快,刚开始时处于“亮态”的罗丹明B分子个数骤减。大约2s后处于“亮态”的分子个数已经很少,之后趋于稳定阶段。通过RhB,RhB-4PEG,RhB-22PEG三种物质在相同的实验条件下,得到的光子数和占空比的信息,可以发现随着聚乙二醇(PEG)单元数的增加,罗丹明B与聚乙二醇链接产生的衍生物的光子数和占空比都有先增大后减小的趋势。在接下来的工作需要找到具有合适单元数的聚乙二醇与罗丹明B的衍生物,使得其光子数尽可能大,而占空比尽可能小,以达到优化超分辨荧光图像的目的。更多还原

【Abstract】 The energy transfer system and super resolution fluorescence microscopy are two major research topics, the former will help us understand the energy transfer process of photosynthesis, and the latter can facilitate the study of biological samples, specifically having a great significance to study the fine structure of the cells and interaction in cells. In this paper, we hope to explore the energy transfer system and super resolution fluorescence microscopy by synthesizing rhodamine derivatives, and to understand its intrinsic mechanism.Chapter 1 is mainly related to the background knowledge and theoretical basis. mainly divided into two parts, the fluorescence principle and the background knowledge of super resolution fluorescence microscopy. The fluorescence principle part includes:fluorescence excitation and emission, energy transfer, exciton, fluorescence lifetime and quantum yield, steady-state and time-resolved fluorescence spectroscopy and fluorescence spectrometer. And the Energy transfer part is divided into fluorescence resonance transfer energy (FRET) and electron exchange energy transfer. The exciton part contains Frekel exciton and Wannier-Mott exciton. The super resolution fluorescence microscopy part includes:the diffraction limit and super resolution fluorescence microscopic imaging technique. Among them, the super-resolution fluorescence microscopy imaging technology mainly introduces the stimulated emission depletion technique (STED), the structure light microscopy technique (SIM), the photo-activation localization microscopy technique (PLAM) and the stochastic optical reconstruction microscopy technique (STORM).In chapter 2, we demonstrate a highly fluorescent polymer consisting of repeating pendant dye molecules, difluoroboron dibenzoylmethane (BF2dbm), and an end-capped Rhodamine B (RhB) exhibits efficient energy transfer (EnT) owing to long-lived polymer excitons. External stimuli such as solvation and temperature can dramatically affect the efficiency of EnT and thus change the emission colour. Detailed theoretical calculations and ultra-fast laser spectroscopy studies on the donor-acceptor polymers reveal that in dilute solution intrachain BF2dbm aggregates lead to more forbidden and nearly degenerate singlet and triplet states. Thus these aggregate species serve as an exciton reservoir after photo-excitation, which is readily harvested by the RhB acceptor dye and contributes to the observed high EnT efficiency. The model system shows that very efficient EnT can be realized through long lived excited states in metal-free systems.In chapter 3, we can easily get a series of Rhodamine B derivatives with methyl terminated polyethylene glycol (RhB-4PEG. RhB-7PEG, RhB-10PEG, RhB-22PEG) using the esterification (DMAP and EDC·HCl as a catalyst). The photobleaching rate of Rhodamine B is very fast, after excitation about 2 s, the number of molecules which are in the "bright" state is very small, and then tends to be stable. Under the same experimental conditions, the photon number and the duty ratio of RhB, RhB-4PEG, RhB-22PEG show that with the increase of polyethylene glycol (PEG) unit number, the photon number and duty ratio of the Rhodamine B derivative increases first and then decreases. In the next work, we need to find a Rhodamine B derivative with suitable unit number of polyethylene glycol (PEG), making the photon number as much as possible while the duty ratio as small as possible, and achieving the optimization of super-resolution fluorescence images.更多还原