The Application Of Nanoparticle And Polydopamine Coating Layers In Chiral Capillary Electrophoresis

Coating technology, namely modification of the inner wall of the capillary, is the simplest and most effective way to suppress disadvantageous adsorption, and to improve the separation efficiency and analysis repeatability. Using the coating technology, chiral selectors can be fixed on the inner wall of the capillary to get a chiral capillary column. The wide applications of all kinds of coating technology greatly promote the development of the technique of capillary electrophoresis. The thesis mainly includes the following three parts:In chapter 1, the importance of chiral separation and the development of chiral separation technology were introduced. Capillary coating methods were summarized and the applications of capillary coating technology in chiral separation were reviewed.In chapter 2, diamino moiety functionalized silica nanoparticles with the size of 118±12 nm were successfully synthesized and directly introduced into a chiral capillary electrophoresis system to improve the enantioseparation of 9-fluorenyl methoxycarbonyl derivatized amino acids using norvancomycin as chiral selector. Under acidic background electrolyte conditions, functional silica nanoparticles can be readily adsorbed onto the inner surface of bare silica capillary column through electrostatic interaction to form a dynamic coating, resulting in a reversed anodic electro-osmotic flow(i.e. from cathode to anode). As expected, chiral amino acid derivatives(usually negatively charged) can be rapidly separated under co-electro-osmotic flow conditions in the current separation system. Furthermore, the column performance and detection sensitivity for the enantioseparation were also obviously improved because the adsorption of chiral selector of norvancomycin to the capillary wall was greatly suppressed. Some important factors influencing the separation were also investigated and the optimized separation conditions were obtained.In chapter 3, coated capillary column was prepared using dopamine, a relatively new coating material. Owing to the strong adhesive force of polydopamine, norvancomycin was embedded in polydopamine, and a chiral capillary column was achieved. Preparation conditions of PDA/NVC coating were investigated, and the coating layers were characterized with scanning electron microscopy(SEM), raman spectroscopy and nuclear magnetic resonance(NMR). The coating column was used to resolve some chiral compounds and the chiral separation of propranolol was realized. Problems still existing in the experiment were discussed, and the development of the method was also expected.In chapter 4, two subjects in this paper are summarized here, and the development of coating layers preparaed and the preparation technology involved is prospected.