【作者】 宋兴良；

【导师】 王江涛；

【作者基本信息】 中国海洋大学 ， 海洋化学， 2010， 博士

【摘要】 分子印迹聚合物(molecularly imprinted polymers, MIPs)是制备对特定分子具有专一性结合能力的高分子技术。MIPs具有亲和性好、选择性高、抗干扰性强、稳定性好,使用寿命长以及应用范围广等优点。目前,分子印迹技术已在环境检测、天然药物分离以及色谱分析等领域得到广泛应用。采用传统本体聚合所制备的MIPs对目标分子的结合量小,可接触性差,在制备过程中所使用的模板分子难以完全洗脱,影响检测的准确性。为有效克服上述缺点,近几年相继出现了一些新的印迹技术解决这些问题,如表面分子印迹法、悬浮聚合法、虚拟模板分子印迹法等。本论文取得的主要研究成果包括：1.以槲皮素分子为模板,以丙烯酰胺为功能单体、乙二醇二甲基丙烯酸酯为交联剂,通过热引发聚合方法制备了分子印迹聚合物(MIPs),并结合傅里叶变换红外光谱和扫描电镜对MIPs进行了表征。紫外光谱研究证实了槲皮素与单体之间可以通过氢键作用形成1:4型配合物。采用Scatchard模型和Langmuir-Freundlich模型分析表明所制备的MIPs具有均一的结合位点。结合量子化学中的密度泛函计算,系统考察模板分子、功能单体和交联剂溶剂化能的大小对槲皮素分子印迹聚合物分子识别能力的影响,实验表明,以极性较小的四氢呋喃为溶剂和极性较小的EDMA为交联剂所制备的MIPs具有较好的分子识别能力,这就为印迹聚合物合成时正确选择功能单体、分散溶剂及交联剂提供理论依据。以儿茶酚和芦丁为模板相似化合物,用液相色谱探讨了MIPs柱对槲皮素的保留效果,评价了MIPs的选择性识别能力；利用所制备的MIPs为固相萃取吸附剂对侧柏叶提取物进行了萃取和富集以及高效液相色谱分析,表明MI-SPE柱对槲皮素具有很好的亲和性和分子识别能力,分子印迹-固相萃取法将为用于富集和测定天然产物中的黄酮类化合物提供一种新颖的方法。2.基于分子印迹-溶胶凝胶技术(molecularly imprinted sol-gel materials, MISGMs)在硅胶表面制备了对2,4-二甲基苯酚分子具有选择性识别能力的分子印迹聚合物,并对2,4-二甲基苯酚分子印迹硅胶吸附剂和非印迹硅胶吸附剂进行了红外光谱表征。以双酚A为竞争分子的静态吸附实验表明：相对于双酚A,印迹硅胶吸附剂对2,4-二甲基苯酚表现出显著的选择性吸附能力,印迹和非印迹硅胶吸附剂对2,4-二甲基苯酚的最大静态吸附量分别为374和171μg.g-1。MIP对2,4-二甲基苯酚的因子值为2.2。而后,以MIP为固相萃取吸附剂结合高效液相色谱测定海水中的2,4-二甲基苯酚的回收率为82.4%(RSD为5.1%)。实验表明,基于表面印迹技术的MISGMs使识别位点暴露在载体的表面,减少模板分子的“包埋”现象,提高传质速率,有利于模板的洗脱和分子识别。3.以萘和蒽为双模板分子,以甲基丙烯酸为功能单体、二甲基丙烯酸乙二醇酯为交联剂,以聚乙烯醇(PVA)为分散剂,采用悬浮聚合法制备了双模板分子印迹微球。用扫描电镜(SEM)表征微球形貌,考察了搅拌速度对交联微球的成球性能的影响；用静态吸附法研究单、双分子印迹微球的吸附特性,并通过紫外光谱法分析了双模板分子印迹效应产生的原因,为双模板或多模板分子印迹合成提供理论依据。静态吸附实验和Scatchard分析显示,以甲基丙烯酸为功能单体的双分子印迹微球可以形成两类结合位点,并求算了两类不同结合位点的离解常数。实验表明,双模板分子的作用模式优化了分子印迹材料的印迹孔穴,增强了印迹聚合物的多抗性,增加了双模板分子印迹微球的分子识别能力。通过分子印迹-分散固相微萃取法考察了双分子印迹微球对海水中2-3环多环芳烃的吸附行为,所制备的双分子印迹微球显示出富集与分离海水样品中2-3个环多环芳烃的良好前景。4.以萘乙酸为虚拟模板,以甲基丙烯酸为功能单体、二甲基丙烯酸乙二醇酯为交联剂,用表面印迹-牺牲硅胶法合成了萘的分子印迹聚合物。运用理论化学计算初步探讨了功能单体的筛选方法,利用平衡吸附法考察了印迹材料对海水中萘、蒽、菲化合物选择识别特性,用红外光谱和扫描电镜表征了对印迹聚合物的物理性能。本文用结构类似物为虚拟模板代替模板分子可以解决模板的渗漏问题,这种模拟的分子印迹法是非共价印迹的一种扩展。实验表明,以α-萘乙酸分子为模板的分子印迹聚合物除了对萘具有较好的识别能力以外,由于α-萘乙酸中存在羧基而使得MIP的印迹空穴与菲的体积大小相匹配,所以也表现出对菲的独特吸附能力。5.建立了一种富集倍数更高、消耗溶剂更少的新型样品萃取富集技术结合气相色谱-质谱技术来测定海水中多环芳烃(PAHs)类有机污染物的新方法。本文建立的USA-DLLME-LSC实验方法为：取6mL海水样品于带尖底的10mL离心试管中,加入6.15mol·L-1的氯化钠溶液0.05mL、80μL萃取剂(3：7四氯乙烯和乙醚的混合溶液,V/V),在35℃水浴条件下超声5min,调节离心机转速为8000rpmin,离心5 min。对海水中16种PAHs的富集倍数达到762-8133倍,检出限达到0.05-10ng·L-1,明显优于传统方法。此法用于模拟海水中16种PAHs的加标回收率为87-145%,实际海水中16种PAHs的加标回收率为67-122%,对于简单而快速地测定海水中的多环芳烃具有较高的实际应用价值。更多还原

【Abstract】 Molecularly imprinted polymers are specific high polymer materials that have the selective binding ability to the particular molecules. Molecularly imprinted polymers have many advantages of good affinity, high selectivity, powerful anti-interference performance, better stability, as well as long life and wide range of applications. Molecular imprinting technology had been widespread used in more fields such as environmental monitoring, natural products separation and chromatographic analysis. But the preparations MIPs by using traditional bulk polymerization have many disadvantages, such as small binding capacities to templates, bad accessibility, difficult to completely eluting templates from MIPs, and as well as resulting in the determination accuracy. So it appears some new molecular imprinting technologies to solve the problems in these years, for example, surface imprinting technique, suspension polymerization, analog-imprinted polymer, and so on. As following were primary research results to be acquired in this paper:1. Molecular imprinted polymers (MIPs) were prepared through thermal polymerization by using quercetin as the template molecule, acrylamide (AA) as the functional monomer and ethylene glycol dimethacrylate (EDMA) as the cross-linker in the porogen of tetrahydrofuran (THF). The synthesized MIPs were identified by both Fourier transform infrared (FTIR) and scanning electron microscope (SEM), and it was showed that the complex ratio between AA and quercetin was 1:4 studied by UV spectrum. Systematic investigations of the influences of key synthetic conditions, including functional monomers, porogens and cross-linkers, on the recognition properties of the MIPs, such as THF and EDMA were conducted by using Computational quantum chemical analysis. Scatchard and Langmuir-Freundlich analysis revealed that the homogeneous binding sites were formed in the polymers. Besides quercetin, two structurally similar compounds of rutin and catechol were employed for molecular recognition specificity tests of MIPs. Binding study demonstrated that MIPs showed excellent affinity and high selectivity to quercetin. Accordingly, the MIPs were used as a solid-phase extraction (SPE) sorbent for the extraction and enrichment of quercetin in cacumen platycladi samples, followed by HPLC-UV analysis. The application of MIPs with high affinity and excellent stereo-selectivity toward quercetin in SPE might offer a novel method for the enrichment and determination of flavonoid compounds in the natural products.2. A novel molecularly imprinted sol-gel material was synthesized by combining a surface molecular imprinting technique with a sol-gel process on the supporter of amino-functionalized silica gel for solid-phase extraction-high performance liquid chromatography (SPE-HPLC) determination of 2.4-dimethylphenol (DMP). Non-imprinted silica sorbent was synthesized without the addition of 2,4-dimethylphenol using the same procedure as that of MIPs. The 2,4-DMP-MIP and NIP were characterized by FT-IR and the static adsorption experiments. It was showed that the prepared DMP-imprinted silica sorbent had good performances of high adsorption capacity and good site accessibility for 2,4-DMP. The maximum static adsorption capacity of the MIP and NIP for DMP was 374 and 171μg.g-1, respectively. The relatively selective factor value of this DMP-MIP was 2.2, and the 2,4-DMP-MIP was used as the sorbent in solid-phase extraction to determine 2,4-DMP in seawater samples with satisfactory recovery higher than 82.4%(RSD 5.1%). It was obvious that the MIP-SPE-HPLC method showed a higher selectivity to DMP, because the molecularly imprinted sol-gel materials by surface molecular imprinting technique could reduce the embedding phenomenon of MIP to templates, and resulting in speeding up mass transfer and benefitting templates eluting or rebinding in MIPs.3. Double molecularly imprinted polymeric microspheres (DMIPMs) was prepared via heat-initiating polymerization with naphthalene and anthracene as the template molecule, acrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross linker and polyvinyl alcohcol as dispersant by using suspension polymerization. Dispersive solid-phase microextraction method was proposed to study the molecular recognition of 2-3 cycles PAHs pollutants in seawater with the DMIPMs. The effects of mixing speeds to spherulization were characterized by means of SEM. The reason of double template molecule molecular imprinting effect occurred was studied by ultraviolet spectra method. It was studied of the two selective sites in DMIPMs by static adsorption experiments and Scatchard analysis. Experimental results show that the prepared DMIMP exhibits high selectivity and good recognition ability to naphthalene and anthracene than that of the MIPMs using single template molecule. The possible reasons were that the mutual effect model of double template molecule optimizing the cavities of molecularly imprinted polymer (MIP) and increasing the multi-resistance of MIP. The recognition ability of prepared DMIPM didn’t show descend even if the DMIPM was used repeatedly for 3 times. The preparation of the DMIPM provides an innovative opportunity for the development of the novel material for selective enrichment and determination of trace 2-3 cycles PAHs in complex seawater.4. A novel surface imprinting material was synthesized using a template immobilized on a modified silica gel matrix where naphthyl acetic acid was grafted to aminopropyl silica. The silica template conjugate was co-polymerized with a functional monomer (methacrylic acid) and cross-linker (ethylene glycol dimethacrylate), and then the silica-polymer composites were treated with an aqueous NH4HF2 solution to dissolve the silica matrix. FT-IR spectrum and scanning electron microscope (SEM) were adopted for characterization the surface and structure of the molecularly imprinted polymer. The binding energy of imprinted molecule with functional monomer was calculated by using the density functional theory (DFT) method, and the largest binding energy could be chosen for the synthesis of molecularly imprinted polymer (MIP). Competitive rebinding test was carried out in seawater media, and the selective adsorptions of target molecule on MIP were studied. The resulting polymer was found as specific affinity toward naphthalene and phenanthrene. The reason for the higher sensitivity to phenanthrene owe to the size of the carboxyl group, where the imprint molecule was larger than naphthalene. So it was possible to preconcentrate the structural analogues of naphthalene for seawater by using the analog-imprinted polymer in the future.5. The coupling of ultrasound-assisted dispersive liquid-liquid microextraction with little solvent consumption (USA-DLLME-LSC) for gas chromatography-mass spectrometry (GC-MS) determination of 16 typical kinds of polycyclic aromatic hydrocarbons (PAHs) in seawater samples was studied. Some important factors that potentially affecting the microextraction processes and the enrichment efficiency were systematically investigated, such as extraction solvent, dispersive solvent, phase ratio, extraction temperature and time, sodium chloride concentration, and content of humic acid. A 6 mL seawater sample was placed in a 10 mL glass-centrifuge tube. Then 0.05mL 6.15 mol. L-1 NaCl and 80μL mixed organic solvents (TCE:DE=3:7, V/V) were added into the tube. The resulting mixture was immersed into an ultrasonic bath for 5 min at 35℃. The resulting emulsion solution was centrifuged at 8000 rpm for 5 min and then 1μL aliquot of the TCE phase was removed from the conic bottom of the centrifuge tube and injected into GC-MS system for analysis. Under the optimized conditions, enrichment factors (EFs) ranging from 722 to 8133 were obtained, and allowing achieving limits of detection at 0.05-10.0ng.L-1.The proposed USA-DLLME method attained about 1.1-10 times higher EFs than those in the traditional DLLME method. The recoveries of PAHs from simulated seawater samples were 65-145%, that for real seawater was 67-122%, correspondingly. So the USA-DLLME coupled to GC-MS was successfully applied to determinate PAHs in the environmental seawater samples.更多还原