The Study Of Capillary Electrophoresis Based On Quantum Dots And Its Application

As a high-performance separation tool, capillary electrophoresis (CE) has earned popularity in nanomaterial research, especially in the separation of nanomaterial and the applications study basing on nanomaterial.Typically, quantum dots (QDs) nanomaterials have been widely applied as ideal probes for heavy metal ions detection due to their unique optical properties. To further develop and design more effective sensors, it is essential to reveal the accurate mechanism of interaction between QDs and heavy metal ions. Although several interaction mechanisms have been reported, a separation process that can distinguish and identify specific interactions among the free ligands, the capping ligands of QDs, and heavy metal ions is needed to clarify the michanisms involved. Therefore, a CE method was introduced and developed for the mechanism study to obstain more intuitive and sound results.Recently, as the representative of carbon nanomaterial, carbon quantum dots (CQDs) taking the advantages of facile synthesis, excellent photochemical stability and environmental friendliness, have found rising applications in the fields including bioimaging, chemical sensing and optoelectronics. Notably, functionalization of nonmaterial was a hot research approach to broaden the application of CQDs in separation science. After being surface modified with ?-cyclodextrin (?-CD), functionalized CQDs integrated the cativity selectivity of P-CD and the like-graphene structure of CQDs. In this dissertation, ?-CD functionalized CQDs (?-CD@CQDs) were first used as the CE pseudostationary phases (PSPs) for the separation of five aromatic hydrocarbons (AHs) and four racemic drugs.In view of the above, to explore the interaction mechanism between QDs and heavy metal ions as well as the applications of functionality CQDs as PSPs in CE, innovative reserches were carried out basing on the previous works. This dissertation is divided into four chapters, and a brief introduction is as follows:Chapter 1 This chapter briefly introduced the development of capillary electrophoresis and quantum dots, especially reviewed the applications of capillary electrophoresis in the characterization and separation of nanomaterial and the applications of nanomaterial as pseudostationary phases in capillary electrophoresis, and simply described the feature and application of ?-CD functionalized nanomaterial.Chapter 2 In this chapter, CE was employed to explore how L-cysteine-capped-CdTe QDs (L-cys-CdTe QDs) interacts with Hg2+. The change in electrophoretic mobility can synchronously reflect the change in the composition and property of QDs. The effects of the free and capping ligands on the system are discussed in detail. ESI-MS, dynamic light scattering (DLS), zeta potential, and fluorescence (FL) were also applied as cooperative tools to study the interaction mechanism. Furthermore, the interaction mechanism, which principally depended on the concentration of Hg2+, was proposed reasonably.Chapter 3 In this study, ?-cyclodextrin (P-CD) functionalized carbon quantum dots (P-CD@CQDs) were first used as the pseudostationary phases (PSPs) in capillary electrophoresis (CE). The new PSPs have a good performance on the separation of five aromatic hydrocarbons (AHs). CA-CQDs, P-CD, and the precursors of ?-CD@CQDs including citric acid modified P-CD (CA-?-CD) and BPEI functionalized CQDs (BPEI-CQDs) were also used as PSPs at their respective optimal conditions. However, ?-CD@CQDs demonstrated the best separation performance, which should be attributed to the cavity selectivity of P-CD and the "?-?" stacking interaction between CQDs and AHs.Chapter 4 Furthermore, we extended the applications of ?-CD@CQDs as PSPs to the capillary electrophoresis enantioseparation. Four racemic drugs, terbutaline, chlorpheniramine, verapamil and carvedilol, were baseline separated. The effects of pH and concentration of background electrolyte, organic addtives and concentration of PSPs on the enantioseparation were carefully explored. Moreover, the possible separation mechanism was discussed. This method needs not complicated capillary coating or cumbersome treatment, and demonstrates good enantioseparation performance.