【作者】 高大明；

【导师】 张忠平；

【作者基本信息】 中国科学技术大学 ， 无机化学， 2007， 博士

【摘要】 分子印迹技术(Molecular imprinting technology)是一种制备对特定分子具有专一识别性能的聚合物的技术，分子印迹聚合物(molecularly imprinted Polymers，MIP)对模板分子的识别具有构效预定性、特异识别性和广泛实用性等优点。并且，基于分子印迹技术制备的分子印迹聚合物材料具有高亲和性和选择性、抗恶劣环境能力强、稳定性好、制备成本低、使用寿命长，应用范围广等优点而在分离提纯、免疫测定、生物模拟、仿生传感、催化、环境的痕量分析、药物释放等以及相关领域显示出广阔的应用前景。本文首先对分子印记技术的基本原理、分子印记聚合物的制备、分子印记技术应用状况以及分子印记技术新发展和荧光发射能量转移机理进行了较为全面的综述和评价，探讨了当前分子印记技术所面临的机遇和挑战。一种理想的分子印记材料应该具备模板分子能完全除去，印记材料能后功能化，具有完整、均一和稳定的印记位点，对目标分子具有高亲和力，快速结合动力学等特点。但是通过传统方法制得的印记聚合物上大多数分子识别位点都包埋在高交联密度的聚合物内部，从而导致了分子印记材料虽然具有较高的分子识别选择性，但具有结合容量低、位点可接近性差以及结合动力学慢的特点。因此，通过控制印记位点位于合成印记材料表面，对提高印记位点的有效性和位点可接近性具有十分重要的意义，作为一种可以选择的印记方法，纳米结构分子印记材料具有较高的比表面积，印记材料上大多结合位点位于或接近材料表面，所以发展合成纳米结构分子印记材料有望真正解决传统分子印记遇到的困难，以便进一步推动分子印记技术的发展。本论文重点针对TNT分子识别与探测，运用纳米技术、表面功能化设计和分子印记技术等手段，发展制备具有高密度印记位点、高选择性、高亲和力和快速结合动力学的TNT印记芯-壳型纳米二氧化硅复合物壳层，同时，探索纳米结构分子印记材料和荧光发射能量转移对痕量目标分子TNT的识别特性和敏感机制。二氧化硅成为关注的热点是因为其是工艺研究中重要的媒介材料。二氧化硅材料功能化的提升促进了人们重新认识其性质的兴趣。丰富了我们对其基本性质地理解，提升了当前存在应用特性。通过化学修饰方法使单分散的二氧化硅凝胶纳米粒子作为表面纳米印记结构的印记模板分子的支撑体，因为二氧化硅纳米粒子支撑体同有机材料的支撑体相比拥有明显的优点：(a)二氧化硅表面可以修饰从而导致形成不同的硅烷化试剂，在这种无机物的结构中带有许多的功能基团；(b在二氧化硅支撑体的表面被修饰上功能基团是相对容易的反应，这点是不同于有机材料的支撑体；(c)在有机溶剂里二氧化硅支撑体并不溶胀；(d)对有机溶剂的化学惰性。(e)二氧化硅拥有很高的热稳定性；(f)粒径和分散性可控。拥有一致粒径和形状的二氧化硅不仅在处理动态行为和粒子体系稳定性的物理化学领域得到的广泛的应用，而且在分离、催化、陶瓷、涂料和照相的感光乳液等工业上的应用。单分散二氧化硅粒子是在混合了醇、水和氨水的条件下通过硅烷化试剂的水解和缩合反应制备。实验结果显示在以氨水为催化剂、乙醇为溶剂正硅酸乙酯、水为反应物料通过水解和缩合反应可以制的粒径和单分散的二氧化硅纳米粒子，有许多关于这个反应体系的机理研究。然而，这里通过对影响因素的研究，如反应物TEOS、氨水和水的量以及反应温度的变化来获得合适粒径和单分散的印记模板分子的支撑体二氧化硅纳米粒子。随后，用两步化学修饰过程得到丙烯酰胺覆盖的二氧化硅粒子。首先，在氮气气氛中惰性溶剂里APTS通过共价耦联到二氧化硅纳米粒子的表面。然后，富含氨丙基的二氧化硅粒子表面通过与丙烯酰氯的酰化反应，得到表面富含丙烯酰胺功能单体的二氧化硅粒子。修饰的粒子性质和形貌分别用SEM、TEM和FT-IR进行表征。以TNT分子为目标分析物，一种在二氧化硅纳米颗粒表面修饰功能单体诱导策略对TNT分子高密印记。结果进一步证明了二氧化硅表面乙烯基单体层不仅能够在二氧化硅表面通过乙烯基单体和功能单体的引导印记聚合，而且通过TNT分子与功能单体层电荷转移形成复合物驱使TNT模板分子形成聚合物壳层。这两种基本过程导致形成核-壳厚度一致的TNT印记的纳米颗粒，所得的芯-壳型分子印记聚合物的壳厚可调且拥有高密度的有效识别位点。一种渐进式聚合反应被设计用来在二氧化硅表面制备可调控高质量TNT印记的聚合物。同传统的印记聚合物粒子相比，拥有高密度表面印记的聚合物壳层能够明显地提高结合量，加速结合动力学和识别的选择性。通过壳厚的变化与最大饱和结合量的关系，得到分子印记聚合物对最大TNT结合量的壳厚临界值。这些将提供进一步的洞察分子印记有效壳的厚度和印记材料的形式。这一结果不仅能够在分子印记技术方面的应用而且可以成为一种的新的在二氧化硅纳米粒子支撑体上制备聚合物涂层方法。以TNT分子为目标分析物，在液相和气相环境中发现一种用荧光发射能量转移策略对2，4，6-三硝基甲苯(TNT)超痕量探测。这种基于荧光发射能量转移的纳米粒子传感器是在二氧化硅纳米粒子表面通过用硅烷化耦联反应使氨基和荧光染料分子共价反应合成的。实验结果已经证实了富电子的氨基配合物(3-aminopropyltriethoxysilane，APTS)能够通过形成电荷转移复合物作用特定的结合缺电子芳香苯环硝基化合物TNT，在二氧化硅粒子表面所得到的APTS-TNT复合物能够强烈的吸收染料荧光分子的发射光。这两个在二氧化硅表面上发生的基本过程是通过荧光发射能量转移淬灭机理导致对TNT分子快速地、选择性响应。二氧化硅纳米粒子自组装荧光阵列是通过在刻蚀阵列阱的硅片上自组装形成，这种纳米粒子荧光阵列在超痕量的TNT溶液中能够很敏感的探测到大约皮克级的TNT，同样在汽相中能够探测到数个ppb的TNT蒸气。同时，通过高效的荧光淬灭可以选择性的区分TNT与其他几种硝基化合物。这里报道的结果将为其他目标分析物如金属离子、生物分子检测提供一种新颖的、基本的纳米传感器设计方法。更多还原

【Abstract】 Molecular imprinting technique （MIT） is becoming increasingly recognized as a powerful technique of preparing synthetic polymers that contain tail-made recognition sides for certain molecules. The most significant advantages of molecularly imprinted materials are high affinity and high selectivity to analyte, mechanical/chemical stability, low cost and ease of preparation, usage of long lifetime, and hence have attracted extensive research interests due to the potential application in purification, separation, immunoassay, biomimics, chemical and biological sensors, catalysis, environment detection, drug release and other relevant fields for its predetermination, specificity and practicability of molecule recognition.The research described in this thesis gives a brief overview of the development of novel strategies facilitating advanced understanding of the fundamental principles governing selective recognition of molecularly imprinted polymers and fluorescence emission energy transfer （FEET） at molecular level, which is a prerequisite for the rational optimization of biomimetic and sensor materials, and discusses the problems and challenges that molecular imprinting technique meets with at present. Ideal molecularly imprinted materials should exhibit these characteristic as follow: complete removal template molecules, able to be post-synthetically functionalized, homogeneous imprinted sites of high stability, high affinity, rapid binding kinetics and transduction of binding into easy readout etc. However, traditional molecular imprinting techniques often produce the polymer materials exhibiting high selectivity but low binding capacity, poor site accessibility, and slow binding kinetics due to most imprinted recognition sites to be embedded in high rigid polymer matrix interior. Therefore, controlling template molecules to locate in the proximity of materials surface is critical to create more effective recognition sites and to improve sites accessibility. As an alternative to these approaches, nano-sized imprinting materials may provide a potential solution to these difficulties due to their extremely high surface-to-volume ratio which lead to the recognition sites to locate in the proximity of materials surface This thesis aims at an exclusive TNT recognition and detection. The nanoshell of TNT-imprinted SiO₂@MIP nanoparticles with high density imprinted sites, high selectivity, high affinity and rapid binding kinetics had been prepared by means of using nanotechnology, surface functionalized design and molecular imprinting technique etc. Moreover, molecular properties and sensitivity mechanism of nanostructured molecularly imprinted materials and fluorescence emission energy transfer （FEET） on silica surface to trace TNT molecular were also investigated.It is well known that silica has been of considerable interest because it forms the basis of technologically important materials. The ability to functionalize silica materials has prompted a renewed interest in enriching our understanding of its fundamental properties and enhancing its performance in currently existing applications. Monodisperse silica colloidal nanoparticles were suitably used as the imprinted-template substrates of surface nanostuctured molecule imprinting through the chemistry modification. because this support offers pronounced advantages over the organic supports, such as: （a） the immobilization on silica results in a great variety of silylating agents, allowing a myriad of pending functional groups in the inorganic framework; （b） functional groups immobilized on the surface react easier oninorganic support, whose behavior, differs from the organic support. （c） the inorganic supports do not swell in organic solvents; （d） it is resistant to organic solvent; （e） silica has a high thermal resistance and （f） the controllable size and dispersivity of the particle.Monodisperse silica colloidal particles that are uniform in size and shape have extensive application not only in the field of physical chemistry dealing with dynamic behavior and stability of particle systems, but also in industries involving catalysts, chromatography, ceramics, pigments, photographic emulsion, etc. Monodisperse silica particles can be prepared by hydrolysis and condensation of alkoxysilanes in a mixture of alcohol, water, and ammonia. The results have demonstrated the formation of monodisperse silica particles through the hydrolysis and condensation of tetraethylorthosilicate （TEOS） in ethanol with ammonia as catalyst, many studies have been made on the many mechanisms of this reaction system. However, herein, the size and dispersivity of silica particles were investigated through the effective factors of reaction, such as, reactant concentration （TEOS, ammonia aqueous and demonized water）, reaction temperature. Therefore, the suitable size and dispersivity of silica particles that is imprinted as support were achieved by the effective parameters of change reaction condition. Subsequently, the monodispersive silica particles are chemically modified using a two-step procedure to obtain the acrylamide-monomer-capping silica particles. Firstly, Aminopropyl modification of silica nanoparticles was carried out through the covalently attached to silica surface using 3-aminopropyltriethoxylsilane at inert solvent under nitrogen atmosphere. Then, the resultant amino end groups of APTS monolayer were further acryloylated with acryloyl chloride （CH₂=CHCOCl）. Finally, the AA-APTS-silica particles were obtained. The nature and morphology of particles was investigated by scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and FT-IR.Herein, TNT used as analyte, a surface functional-monomer-directing strategy for the highly-dense imprinting of 2, 4, 6-trinitrotoluene （TNT） molecules at the surface of silica nanoparticles was investigated. It has been demonstrated that the vinyl functional-monomer layer of silica surface can not only direct the selective occurrence of imprinting polymerization at the surface of silica through the copolymerization of vinyl end groups with functional monomers, but also drive TNT templates into the formed polymer shells through the charge-transfer complexing interactions between TNT and the functional-monomer layer. The two basic processes lead to the formation of uniform core-shell TNT-imprinted nanoparticles with a controllable shell thickness and a high density of effective recognition sites. A stepwise progressive polymerization was designed toward the controllable preparation of high-quality shell of TNT-imprinted polymers in the silica surface. Compared to traditional imprinted particles, the imprinted nanoshell with high density of surface imprinted sites can significantly improve the binding capacity, binding kinetics and recognizing selectivity. A critical value of shell thickness for the maximum rebinding capacity was determined by testing the evolution of rebinding capacity with shell thickness, which provides new insights into the effectiveness of molecular imprinting and the form of imprinted materials. These results reported here can not only find many applications in molecularly-imprinting techniques but also form the basis of a new strategy for preparing various polymer-coating layers on silica support.Herein, TNT used as analyte, the finding of an investigation of fluorescence emission energy transfers （FEET） strategy for the ultratrace dectetion of 2, 4, 6-trinitrotoluene （TNT） in solution and vapor environments was reported. The FEET-based nanoparticle sensors were synthesized by covalently linking fluorescent dyes and amine ligands onto the surface of silica nanoparticles through the use of alkoxysilane coupling reactions. It has been demonstrated that electron-rich amine ligands （3-aminopropyl triethoxysilane, APTS） can specifically bind TNT molecule with electron-deficient aromatic ring by the charge-transfer complexing interaction, and the resultant APTS-TNT complex strongly absorbs the fluorescence emission of the chosen dye molecules. The two basic processes occurring at surface of silica nanoparticles lead to the selectivity and rapidly response to TNT by fluorescence quenching. The nanoparticle-assembled photoluminescence arrays through the etched microwells on silicon chip can sensitively detect down to several pg of TNT solution or several ppb of TNT from other types of nitrocompounds by the higher efficiency offluorescence quenching. These results reported herein will also form a novel basis ofnanosensor design for the detection of other analytes such as metal ions and biological molecules.更多还原