| Nowadays, the separation and detection of trace substances in complex matrix is a great challenge of modern separation and analytical science, especially the environmental and biological samples. Metabolomics, which has been developed in the post-genomic era and studied as the complement of genomics and proteomics, can help people to study the life science from metabolic level. Some metabolites are associated with diseases or certain physiological states, so it is very important to detect and identify these biomarkers in diagnosis and therapy of diseases.The environmental and biological samples are usually complex and the matrix effects often interfere with the separation and analysis of the analytes, especially the trace analytes. Therefore, analysis of these components not only relies on modern analytical instrumentation, but also requires appropriate sample pretreatment methods. At present, micro-solid phase extraction technology based on magnetic functional materials is one of the hotspots of sample pretreatment, which is always simple, fast and selective in sample enrichment.In this thesis, we focused on the polymer-functionalized micro/nano materials, the separation methods based on magnetic micro-solid phase extraction and the metabolomics research. A series of work have been carried out and novel analytical methods have been established. The main contents and results are summarized as follows:The first chapter introduces the research significance of sample pretreatment and gives an overview of novel technologies in sample pretreatment. Then it summarizes the development of the functional magnetic materials, combined with the micro-solid phase extraction methods based on functional magnetic materials. In addition, it also introduces the research significance and progress of metabolomics. Finally, it outlines the significance and main contents of this thesis.The second chapter introduces the synthesis and application of polypyrrole-coated Fe3O4magnetic microspheres. The functionalization of polypyrrole prevents the aggregation of magnetic microspheres, modifies the surface with π-conjugated system so that it can adsorb aromatic compounds. Then, we investigated the enrichment ability of this material to extract phthalates from water samples. After optimization of the enrichment conditions and the validation analysis, it was proved that the micro-solid phase extraction based on the proposed material is simple, high sensitive and it was successfully applied to the enrichment and analysis of phthalates in real water samples.The third chapter describes a novel synthetic method and application of polyaniline-modified magnetic microspheres. In this method, magnetic carbon microspheres (Fe3O4@C) were first synthesized via a hydrothermal reaction, and then polyaniline-modified magnetic microspheres (Fe3O4@C@PANI) were synthesized via another hydrothermal reaction. In the latter reaction, the polymerization of aniline was initiated by copper (Ⅱ) acetate and occurred on the surface of magnetic carbon microspheres. The process was simple and facile, without any use of templates. Finally we examined the enrichment ability of this material to extract phenolic compounds from water sample. The results showed our proposed method had good linearity, reproducibility and low detection limit, and also it was successfully applied to the analysis of phenolic compounds in real water samples.The fourth chapter introduces the metabolomic research of morphine-treated mouse brains. First, we applied the conditioned place preference (CPP) model to investigate the mechanism of context-dependent learning associated with rewarding effect of morphine. Then, we analyzed the metabolites in mouse brains of morphine group and controlled group by GC-MS-based analytical platform. A total of69known metabolites were identified. According to Wilcoxon rank sum test,21metabolites with significant change were selected as potential biomarkers. Finally, using principal component analysis (PCA) and receiver-operator characteristic (ROC) curves, a model was constructed with a combination of these21potential markers, and several metabolites were further discussed to study their relationship of morphine-related pathway. The results showed that our technology could be effectively applied to the screening of biomarkers, and it also provided new insights into the mechanisms of drug addiction.The fifth chapter describes a novel synthetic method of multi-walled carbon nanotubes and polyaniline composites (MWNTs@PANI) and its application as a novel matrix in MALDI-MS analysis of small molecule metabolites. The composites were synthesized by a one-step hydrothermal reaction, and the water-soluble polyaniline pellets were evenly coated on the sidewalls of carbon nanotubes, which greatly improved the dispersibility of carbon nanotubes in water. Subsequently, we investigated the capacity of this material as a MALDI matrix, and some common small molecule metabolites were analyzed by MALDI-MS, including amino acids, carbohydrates and fatty acids. The results showed that the material would help to improve the dispersibility of canotubes in water and could be well mixed with the analytes, which contributed to the achievement of a new platform for high-throughput analysis of metabolites based on MALD-MS technologies. |
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