【作者】 韩翠平；

【导师】 李海兵；

【作者基本信息】 华中师范大学 ， 有机化学， 2012， 博士

【摘要】 生命存在的最基本过程是发生在纳米尺度的表界面环境中的一系列分子识别过程,因此,对纳米表界面分子识别与作用机制的研究是从分子水平研究和探索生命现象的重要途径。结合超分子主-客体高选择性识别性能与纳米材料的特性,设计和制备各种高效、灵敏、便捷的功能材料,成为智能传感体系的重要发展方向。环糊精是一种环状低聚糖,具有独特的结构和分子识别特性。本论文在概述了环糊精的分子识别性能以及基于环糊精建立的传感界面的研究背景及最新进展的基础上,着眼于高性能的环糊精功能化的纳米界面的设计与分子识别研究。充分融合纳米材料独特的物理化学性质和环糊精良好的识别性能,建立高效传感方法,研究环糊精功能材料界面的分子间相互作用与信号转换机制,为建立环境、生命复杂体系中的高灵敏测试方法提供理论依据。具体内容如下：1.介绍了了环糊精独特的结构和特性,以及基于环糊精超分子主体化合物功能化的纳米传感器的研究进展,简述了半导体量子点、贵金属纳米粒、纳米通道的性质及其在传感分析中的应用和原理,并由此提出了本论文的设想和研究思路。2.创新性的提出了一种简单的超声振荡方法,将母体环糊精快速组装到量子点表面,使量子点从疏水性转变为亲水性。所制备的超分子纳米复合体同时具有量子点的优良的光学性能和环糊精的分子识别能力,表现出对酚类异构体较好的选择性识别性能。在所考察的8种酚类异构体中(包括邻硝基苯酚、间硝基苯酚、对硝基苯酚、邻甲基苯酚、间甲基苯酚、对甲基苯酚、1-荼酚、2-禁酚),α-、β-环糊精修饰的量子点可以分别对对硝基苯酚和1-萘酚选择性识别,检测限分别为7.92×10-9M和4.83×10-9 M。研究表明,该类探针选择性好,灵敏度高,且制作简单,操作方便。通过对实际环境中的水样进行检测,证明检测探针具有很好的抗干扰性和实用性。3.利用环糊精内在的手性和良好的主-客体包结性能,建立了一种以量子点为荧光探针的手性识别新方法。我们通过简单的组装方法,分别把具有手性识别性能的α-和β-环糊精引入到CdSe/ZnS量子点表面,该类传感器能够有效灵敏地对蛋氨酸和酪氨酸进行手性识别。在一定浓度范围内,L-型的氨基酸使环糊精修饰的量子点荧光强度显著增强,而D-型的氨基酸对量子点的荧光影响不大。环糊精功能化的量子点可以显著提高对手性化合物的对映选择性,对今后手性传感器以及手性识别分析方法的应用和发展都具有重要的意义。4.基于纳米银表面等离子共振性质,建立了一种高选择性稀土离子的识别新方法。以p-环糊精/4,4’-联吡啶(β-CD/4-DPD)超分子配合物为稳定剂和功能基团制备出稳定的、单分散的银纳米粒探针,通过离子加入后引起的纳米溶胶颜色、UV-vis光谱及微观形态的变化来研究纳米探针对稀士离子的识别作用。其中Yb3+离子的加入,使单分散的银纳米逐渐组装成链状的网状纳米结构,颜色由黄色向红色转变,同时吸收波长红移,而La3+、Ce3+、Pr3+、Nd3+、Sm3+和Eu3+离子对溶胶的颜色和UV-vis光谱都没有影响,从而建立了一种高选择性的、新型的稀土离子比色传感方法。5.利用环糊精内在的手性微环境,将其组装到纳米通道内,开发出一个高选择性的手性检测体系。首先通过重离子轰击加径迹化学刻蚀方法(track-etching technique)制备出的单锥形聚合物纳米通道,利用化学蚀刻过程表面产生的羧基将具有手性识别性能的β-环糊精分子修饰到纳米通道内,基于离子电流的不同变化,实现了对组氨酸的手性识别,并可以对异构体进行定量分析。此检测体系具有较好的选择性和重现性,为研究和模拟生物体的手性识别提供了一种新的思路,为新型的手性传感器的设计提供了一种新的方法。更多还原

【Abstract】 The fundamental process of life is a series of molecular recognition at the nanoscale interface, therefore, the study of molecular recognition and mechanism of action at the nanoscale interface is important for exploration of the biological phenomena at the molecular level. The combination of the excellent properties of nanomaterials and the molecular recognition ability of host molecules to design intelligent sensing system is an active line of research, and has contributed to creating a variety of efficient, sensitive, convenient sensing system. Cyclodextrins (CDs) are a class of cyclic oligosaccharides, has a unique structure and molecular recognition characteristics. On the basis of reviewing the molecular recognition properties of CDs and their applications in chemical sensors, this thesis is focused on fabricating novel and efficient CD-functionalized nano-interfaces and exploring their potential applications in molecule recognition.The main contents are shown as following:1. The unique structure and characteristics of cyclodextrin were introduced. The properties and application of semiconductor quantum dots, metal nanoparticles, and nanochannel were outlined. On the basis of the above review we put forward our design ideas and research topics.2. A simple, rapid sonochemical procedure for the preparation of highly fluorescent and water-soluble CdSe/ZnS quantum dots (QDs) usingα-,β-, andγ-CD as surface-coating agents was reported. The functional QDs retained the excellent optical properties of QDs and engaging molecular recognition ability of CDs. These receptor-modified QDs afforded a very sensitive detection system for analysis of phenol isomers. It was found that theα-CD-QDs andβ-CD-QDs were selectively sensitive toward p-nitrophenol and 1-naphthol, respectively. Under optimal conditions, the relative fluorescence intensities ofα-CD-QDs andβ-CD-QDs both decreased linearly with increasing p-nitrophenol and 1-naphthol in the concentration range of 0.01-100μM, with the corresponding detection limits (3σ) of 7.92×10-9 M and 4.83×10-9 M, respectively. However, the sensitivity toward other phenols, including o-nitrophenol, m-nitrophenol, 2-naphthol, o-cresol, m-cresol and p-cresol, were negligible. The results showed that the CD-QDs had a good specificity and excellent anti-disturbance ability.3. A novel chiral fluorescence sensor based on quantum dots was constructed using CD as chiral selector. CDs, with a capability of chiral recognition, were introduced on the surface of CdSe/ZnS QDs by using a simple and convenient sonochemical approach. It has been demonstrated that the CD-QDs can carry out highly enantioselective fluorescent recognition of tyrosine and methionine. Within a certain concentration range, one enantiomer of the chiral amino acids can increase the fluorescence intensity of the CD-QDs, whereas the other enantiomer scarcely influences the fluorescence. Such unusually high enantioselective responses make these CD-QDs very attractive as fluorescent sensors in determining enantiomeric compounds.4. A new colorimetric method base on the surface plasmon resonance of silver nanoparticles (Ag NPs) was demonstrated for determination of rare earth (RE) ions in aqueous solution with high sensitivity and selectivity. A well-stable and dispersed Ag NP probe was synthesized using theβ-cyclodextrin/4,4’-dipyridine (β-CD/4-DPD) supramolecular inclusion complex system as a stable ligand. The recognition ability ofβ-CD/4-DPD-modified Ag NPs for RE ions could be realized by monitoring the UV-vis spectra and color changes of the Ag NPs solution before and after addition of various RE ions. In the presence of Yb3+, Yb3+-induced assembly of theβ-CD/4-DPD-modified Ag NPs to form chainlike supramolecular aggregates, gives a distinct color change from yellow to red and dramatic increase in the absorbance intensity at-610 nm. However, the addition of other RE ions, including Pr3+, Nd3+, Sm3+and Eu3+, no changes in the UV-vis spectra and color of Ag NPs were observed.5. A simple enantioselective sensing nanodevice based on a single conical nanochannel was fabricated in a PET membrane. Chiral recognition elements (β-CD molecules) were incorporated into the channel by directly exploiting the carboxyl groups generated during the track-etching process. The modified nanochannel provided a novel sensing platform to discriminate chiral His based on rectified ionic currents. This successful study is a potential step toward the ability to simulate the process of chiral recognition in living organisms. The artificial nanochannel systems offer real promise for preparing practical chiral-sensing devices that could be employed in a biological environment.更多还原