基于毛细管电泳的复杂基体中量子点与多种配体竞争交换机理的研究方法

Ligand exchange is an important strategy not only for improving the water solubility and biological compatibility of quantum dots (QDs), but also for understanding the interaction between biological particles and ligands. The study on the ligand exchange mechanism can help us understand the QDs-ligand interaction and design novel QDs sensors for practical application. The common techniques used to study the ligand exchange mechanism include transmission electron microscopy (TEM), dynamic light scattering (DLS), atomic force microscope (AFM), infrared spectroscopy (IR), ultravoilet-visible spectroscopy (UV-Vis) and photoluminescence spectroscopy. But all these ensemble techniques stay at a mixture level without a separation process, and are incapable to straightly probe the ligand exchange mechanism. Moreovre, the additional operations to obtain the purified QDs is necessary, such as firstly precipitating from the complex solution and then redispering into another fresh solvent, which easily results in the change of the QDs surface property. Various solution nuclear magnetic resonance spectroscopy (solution NMR) can distinguish the bound and free ligands, so is a powerful tool to qualitatively and quantitatively characterize the ligand exchange on QDs surface. But NMR is only available for the simple system such as one QDs and one new ligand, but incompetent for more complex system. Capillary electrophoresis (CE) is one of the principal separation and analysis techniques with versatile advantages of high efficiency, short analysis time, low sample and reagent consumption. The development of various kinds of CE separation modes and on-column preconcentration strategies makes it a powerful tool for a wide range application. The electrophoretic peak of an analyte is closely related to its charge and size, so CE should be a perfect tool to characterize the ligand exchange mechanism on QDs surface. In the project, based on the changes in the intensity and migration time of CE peak, combining the peak identification from the cooperation of ultraviolet (UV) and laser induced fluorescence (LIF) detections, the ligand exchange mechanism on QDs surface with diffirent sizes/morpholy/structure and capping ligands after adding new ligands will be visualizedly demonstrated. Furthermore, the ligand coordination number on QDs surface and the detailed kenetic process of the ligand exchange can be quantitatively obtained. The strategy is very simplified without the need to purify QDs, therefore it can truly reflect the QDs surface property and demonstrate the process and degree of the competitive ligand exchange in complex matrix. The successful implementation of the project will provide a simple and visualized method to study the interaction and exchange mechanism between biological particles (such as liposome) and ligands (such as amino acids, protein and some drug molecule).

配体交换是改善量子点(QDs)性质和功能的有效手段，也是了解生物颗粒与配体相互作用的重要途径。通过对配体交换机理的研究，可深入理解量子点与配体的作用方式，为新型量子点探针的开发和应用提供一定的理论指导。然而，目前常用的表征手段，如TEM、FT-IR、UV-Vis、荧光、液体NMR等都无法实现复杂基体如生命物体中多种配体的竞争交换研究。毛细管电泳 (CE) 具有高效、快速、经济的优点，谱峰与待测物的电荷和尺寸密切相关，是研究复杂基体中配体交换的理想方法。因此，本项目拟采用紫外和激光诱导荧光两种检测技术、结合CE多种分离模式和柱上富集手段、依据CE谱峰强度和迁移时间的变化，定量进行不同配体与不同粒径/形貌/结构的量子点的竞争交换机理和动力学研究。该方法无需提纯量子点，能真实、直观地反映复杂基体中配体交换的过程和程度，可为生物颗粒(如脂质体)与配体的结合和交换研究提供一种新的方法。

本项目发展了一种基于毛细管电泳研究量子点表面配体交换机理和动力学的新方法。该方法简单、快速，无需对混合溶液进行预处理，可同时分离检测疏水性量子点、疏水性配体、亲水性量子点和亲水性配体。研究结果也表明，量子点表面配体交换的动力学过程与配体交换时间和亲水性配体的浓度有关。建立了一种研究Hg2+猝灭L-半胱氨酸(L-cys)修饰的CdTe QDs的荧光机理的毛细管电泳新方法，并提出了一种比较全面的猝灭剂浓度调控的作用机制。发展了三种生物膜涂层毛细管的新方法，并考察了所制备的毛细管柱用于开管毛细管电色谱分离对映异构体的可行性。实验结果表明，所制备的-环糊精/聚多巴胺涂层毛细管柱对三种单胺类神经递质、三种药物和一种氨基酸的对映异构体均表现出良好的分离效果；以原位聚合的方法制备了聚左旋多巴涂层毛细管，该涂层柱对十对对映异构体具有较好的拆分作用；基于溶菌酶相转变体成膜的特性，制备了超分子膜涂层的毛细管柱，该涂层柱对特布他林、异丙肾上腺素和肾上腺素三对对映异构体表现出良好的分离效果。合成了具有双酶活性的三维石墨烯纳米复合材料3DRGO_Fe3O4-Pd，并建立了比色检测H2O2、谷胱甘肽和葡萄糖的新方法。合成了一些新型纳米探针并研究了其在生命分析化学中的应用。发展了几种基于等温核酸扩增检测生物标志物的新方法。本项目的开展显著提高了毛细管电泳在反应机理和动力学方面的理论和应用研究，也拓宽了纳米材料和等温核酸扩增的应用范围。该项目的研究结果对生命分析化学和纳米分析化学的发展具有重要意义。