分子印迹聚合物的制备及其识别特性的应用研究

【作者】 雷启福；

【导师】 周春山；

【作者基本信息】 中南大学 ， 分析化学， 2005， 硕士

【摘要】 本文在综述了分子印迹技术(molecular imprinting technology, MIT)的基本理论、制备技术及其应用研究进展的基础上,制备了具有分子识别能力的分子印迹聚合物(molecularly imprinted polymer, MIP),采用静态吸附、色谱分离、膜分离、固相萃取、扫描电镜等方法对制备的分子印迹聚合物进行表征和应用,研究内容如下: 1) 采用沉淀聚合方式,以辛可宁(cinchonine, CN)为模板分子,制备了辛可宁分子印迹聚合物微球(CN-MIP)。通过红外光谱、平衡结合方法、Scatchard分析等手段对分子印迹聚合物的分子识别行为、底物结合选择性进行了研究,揭示了CN-MIP的结合机理,为进一步研究MIP提供了理论基础和实验基础。实验表明,制备的MIP对非对映体辛可宁和辛可尼丁的分离因子α可达1.86,而空白聚合物的分离因子α仅为1.02;Scatchard模型分析证明MIP具有两种结合位点,其高、低结合位点的平衡常数分别为131.43μmol/L和2.32mmol/L。MIP微球粒径小而均匀(平均粒径为0.5μm),无需研磨过筛即可使用,并且聚合物本身非常稳定。 2) 采用本体聚合方法制备辛可宁分子印迹聚合物,并把制得的聚合物用作色谱固定相对辛可宁和辛可尼丁进行拆分。实验对模板分子和可聚合的功能单体形成配合物的比例、聚合方式、聚合物用作色谱固定相时的流动相组成、流速、柱压等条件进行了选择和优化。结果表明,当模板分子与功能单体的比例为1:4,采用光冷引发聚合制备的MIP具有良好的色谱分离效果,分离因子α为1.82。得到较优的色谱操作条件为:检测波长280nm,流动相甲醇-氯仿(9:1,v/v),流速0.4mL/min。该方法制备分子印迹聚合物条件容易控制,操作简单,重复性较好。 3) 通过紫外光冷引发制备了分子印迹聚合物(复合)膜,重点研究了以尼龙膜为支撑体的分子印迹-尼龙复合膜的结构和性能。结果显示,该膜表面均匀、膜通量较大、韧性较好、选择性高,对辛可宁和辛可尼丁具有良好的选择性透过拆分能力,为进一步研究分子印迹复合膜提供了实验基础。 4) 采用本体聚合法制备了EGCG((-)-Epigallocatechin-3-gallate)分子印迹聚合物,研究了其识别特性和吸附能力,并用作固相萃取材料分离富集茶多酚中的EGCG。首先通过EGCG与功能单体的紫外更多还原

【Abstract】 Molecular imprinting technology （MIT） has been a hot issue to investigate because which can provide the polymers that have high recognizetion and selectivity properties to objective molecular. On the base of the review to the progress of MIT, following experiments were carried on.1 Using cinchonine（CN） as template molecule, spherical cinchonine imprinting polymers were synthesized by precipitation Polymerization. Their mechanisms of recognition and binding selectivity were explored by IR, equilibrium binding, Scatchard analysis. This could give an impetus to investigate the application of MIP further. The separation factor α between cinchonine（CN） and cinchonidine（CD） was 1.86 by the CN-MIPs, but the factor only 1.02 by non-imprinted polymer（NIP）. Scatchard analysis showed that two sites were produced in the polymer matrix and their equilibrium constants were calculated to be 131.43μmol/L, 2.32mmol/L respectively. And the spherical particles were uniform and stable, their average size was 0.5μm.2 CN imprinting polymer was prepared by bulk polymerization. Conditions of polymerization and operation when the MIP used as chromatography station-phase were selected and optimized. The results showed that better effect could be achieved under 0 ℃ with ultraviolet light in 366nm when the ratio of template molecule to monomer was 1 .’ 4. Diastereoisomers of CN and CD could be separated on the MIP column and the resolution factor was 1.82 using CH₃OH-CHCl₃ （9:1,v/v） as mobile phase in the flow rate of 0.4mL/min. The operation conditions to synthesize the polymer were easy to control and its reproduction was nice.3 On the base of the former researches, imprinted polymer membranes（IPM） were prepared by UV light initiation under 0 ℃. In order to get a better membrane, several experiments were compared such as to directly polymerize a membrane without any backstop, to polymerize with polytetrafluoroethylene（PTFE） or nylon membrane as backstop. The imprinted composite membrane with nylon（Nylon-ICM）had the advantages of uniform surface,better flux, better tenacity and high selectivity property. The good result using Nylon-ICM to separate CN and CD provided an experiment foundation to further investigate imprinted composite membrane.4 Molecular imprinted polymer against Epigallocatechin gallete（EGCG） was prepared and its molecular recognition characteristics to EGCG were evaluated by batch adsorption experiments. At the same time, the EGCG-imprinted polymer was applied to extract EGCG from tea polyphenols（TP） which had been extracted from green tea. Firstly, the presence of hydrogen bond between template and monomer was proved by the change of UV spectrum. Secondly, the special ablity to recognize and bind EGCG was showed by the MIP’s adsorption experiments to EGCG, GCG, EGC and ECG. And the separation factor could be 2.54 between EGCG and GCG The EGCG-imprinted polymer exhibited higher selectivity and better recognition ability to EGCG compared to the non-imprinted polymer（NIP）. In addition, the EGCG-MIP had been used as solid-phase in a column to extract EGCG from TP. The extraction conditions, such as cleaning agent, eluent, uploading quantity, recovery rate, using times, were tested and choosed. The better condition to the column was as following: 7.46mg EGCG per gram to upload, then methanol-water（l ’. 9, v/v） solution to clean the column, methanol-acetic acid （9 * 1, v/v） to elute EGCG from the column. The EGCG recovery rate was 69.3%, and the ablity to recognize didn’t descend when the EGCG-MIP column used 20 times. It’s significative to apply the MIP as solid phase materials to extract effective components from plant extracts according to the MIP’s special ability to recognize the objective molecular.5 Resveratrol imprinted polymer was prepared by molecular imprinting technique, and the MIP was try to use as solid-phase material to separate resveratrol from Polygonum cuspidatum Sieb. et Zucc.extracts. The interactional strength between template and monomer was expressed by infrared spectra. The molecular imprinted polymer was investigated in equilibrium binding experiments to evaluate the molecular recognition and binding characteristics of the Res-MIP.Scatchard analysis showed that two sites were produced in the polymer matrix and their dissociation constants were calculated to be 2.665 X 10 "3mol/L, 7.998 X 10"4 mol/L respectively. The results showed that, compared with non-imprinted polymer（NIP）, the imprinted polymer exhibited much higher affinity for trans-resveratrol among the tested compounds: Res, Pol and BPA. Also, the MIP was applied to separate resveratrol from Polygonum cuspidatum Sieb. et Zucc. Extracts. The purity of the Res’ HPLC Peak was 85.7% and 74.0% recovery rate was obtained.The study on this paper can provide an experiment foundation to further investigate molecular imprinting technology on molecular recognition, membrane separation and solid-phase extraction.更多还原