【作者】 王红飞；

【导师】 张黎明；

【作者基本信息】 中山大学 ， 高分子化学与物理， 2010， 博士

【摘要】 分子印迹材料(MIMs)在分离、传感、药物传输、酶模拟等领域有重要应用。近年来,以天然多糖为基本原料制备多糖基MIMs的研究工作,成为研究的热点。多糖基MIMs具原料来源广泛、生物相容性和生物降解性好等优点。本论文不仅合成了可用于酪氨酸、蛋白质分离的多糖基MIMs,还制备了具有电化学传感、荧光检测、药物缓释功能及酯酶活性的多糖基MIMs。采用红外光谱(FTIR)、扫描电镜(SEM)、热重分析仪(TG/DTG)等研究了所得多糖基MIMs的结构和性能,并利用静态吸附法、电化学法、荧光检测法分别研究了其识别、缓释及催化性能。本工作的主要创新点如下:(1)采用酶促凝胶化法快速制得可用于蛋白质分离的淀粉基分子印迹凝胶,解决了蛋白质印迹过程中易变性失活问题;(2)通过分散聚合法制备了集磁性和温度响应于一体的淀粉基分子印迹微凝胶;(3)以壳聚糖、β-环糊精-异氰酸丙基三乙氧基硅烷偶联物为基本原料,通过溶胶-凝胶法制得具电化学传感功能的分子印迹杂化膜;(4)合成了集识别和荧光响应功能于一体的淀粉基分子印迹凝胶;(5)通过反相乳液法制得具有药物缓释功能和酯酶活性的多糖基分子印迹微凝胶。本论文工作包括如下六个方面:(1)用于蛋白质分离的淀粉基分子印迹凝胶以羧甲基淀粉-氨基苯酚偶联物(CMS-AP)为功能单体,通过酶促凝胶化法制得牛血清蛋白(BSA)分子印迹凝胶(MIHs)。圆二色谱测试表明,BSA与CMS-AP作用后构象未发生改变。用FTIR确定了MIHs中与模板分子相互作用的识别单元。通过流变仪研究了聚合物浓度、CMS-AP上氨基苯酚基团含量等因素对MIHs性能的影响。吸附实验表明,MIHs对BSA的吸附量明显高于non-MIHs的;其对BSA的吸附行为符合Langmuir方程;介质pH为5.0时平衡吸附量最高。选择性吸附实验表明,MIHs的选择性受模板分子用量和CMS-AP上氨基苯酚基团含量影响。(2)用于酪氨酸分离的淀粉基磁性分子印迹温敏微凝胶以羧甲基淀粉-氨基吡啶偶联物(CMS-AP)为功能单体,采用分散聚合法制得磁性分子印迹温敏微凝胶(MMIGs)。用TG/DTG测定了磁性微凝胶的组成;X-衍射(XRD)测试表明,聚合物包覆不会改变Fe3O4的晶相;SEM分析表明,MMIGs粒径为100-500 nm;FTIR分析表明,分子印迹过程中在MMIGs中形成了与模板分子相互作用的识别单元;磁性能测试表明,MMIGs具有超顺磁性。吸附实验表明,MMIGs对酪氨酸的吸附行为可用Langmuir方程进行描述;温度和吸附介质pH对MMIGs吸附酪氨酸有很大影响,在30～40 oC区间发生突变,pH为6.0时平衡吸附量最高。以苯丙氨酸为竞争分子进行的选择性吸附实验显示,MMIGs的分离因子随模板分子和交联剂用量的增加而增大。(3)具电化学传感功能的壳聚糖基分子印迹杂化膜以壳聚糖和β-环糊精-异氰酸丙基三乙氧基硅烷偶联物(CD-IPTS)为基本原料,通过溶胶-凝胶技术制得酪氨酸分子印迹杂化膜(MIMs)。1H NMR测试表明, CD-IPTS与模板分子间能形成稳定的包合物。用FTIR确定了MIMs中与模板分子相互作用的识别单元。吸附实验表明,MIMs对酪氨酸的吸附行为可借助Langmuir方程描述,选择性受交联剂和模板分子用量影响。电化学性能测试表明,电解液pH为7.4、交联剂用量为20 wt%、模板分子用量为3 wt%时,MIMs修饰电极的响应电流最高;10-80μg/mL浓度范围内,MIMs修饰电极的响应电流与浓度呈现出良好的线性关系,线性相关系数达0.998。(4)具荧光检测功能的淀粉基分子印迹凝胶以马来酸酐酯化淀粉-氨基喹啉偶联物(St-MA-AQ)为功能大单体,制得具荧光检测功能的分子印迹凝胶(MIGs)。用SEM和激光粒度分析仪表征了MIGs的形貌、尺寸。吸附实验表明,MIGs对茶碱的吸附过程可用Lagergren一级动力学方程进行描述。以咖啡因药物为对照的选择性吸附实验表明,选择性受模板分子和交联剂用量影响。MIGs对茶碱和咖啡因的等温吸附行为可借助Scatchard方程进行描述,其与茶碱间的亲和力更高。荧光测试表明,MIGs吸附茶碱后发生明显的荧光淬灭现象,且淬灭强度受茶碱的浓度影响;不含底物时MIGs的荧光强度与加入底物后的荧光强度的比值(Io/I)可达1.25;在0-200 ug/mL浓度范围内,(Io/I)值与底物浓度的线性相关系数为0.993。(5)具药物缓释功能的壳聚糖基分子印迹磁性微凝胶以羧甲基壳聚糖(CMC)为基本原料,采用反相乳液法制得对咖啡因具有缓释功能的分子印迹磁性微凝胶(MMIGs)。用TG/DTG确定了磁性微凝胶的组成;XRD测试表明,分子印迹过程不会改变Fe3O4的晶相;SEM分析表明,磁性微凝胶粒径为1-5 um;用FTIR和荧光光谱结果显示,MMIGs中形成了与咖啡因相互作用的识别单元;磁性能测试表明,MMIGs具有超顺磁性。释放实验表明,模板分子用量为4 wt%、交联剂用量为45 wt%时,所得MMIGs对咖啡因释放速率最低,且释放速率随负载量增加而升高;其对咖啡因对释放行为可用Peppas方程进行描述;外加磁场作用可明显降低咖啡因的释放速率并改变药物释放机理;MMIGs对咖啡因的释放速率明显低于其对茶碱的。(6)具酯酶活性的葡聚糖基分子印迹温敏微凝胶以双醛葡聚糖-组氨酸偶联物(PAD-His)为功能大单体,利用反相乳液法制得具有酯酶活性的分子印迹温敏微凝胶(MIGs)。采用紫外光谱研究了模板分子与功能单体间的相互作用。SEM分析表明,MIGs粒径为200-500 nm。催化水解实验表明,当模板分子p-硝基苯磷酸酯(NPP)与咪唑基团摩尔比1:3、交联剂用量为20 wt%时,制得的MIGs催化p-硝基乙酸苯酯(NPA)水解的活性最高,且催化活性受反应介质pH影响;当温度由25 oC升高至38 oC时,催化活性急剧下降;MIGs催化NPA水解反应行为可用Michaelis-Menten方程进行描述,最大催化水解反应速率和Michaelis-Menten常数分别为2.04×10-8 mol/h和2.20×10-5 mol/L,且具有较好的催化选择性。更多还原

【Abstract】 Molecularly imprinted materials (MIMs) have found wide applications in the fields of separation, biosensing, drug delivery and enzyme mimics. In recent years, MIMs based on polysaccharides have attracted great attention due to their abundant raw materials, good biodegradability and biocompatibility. In this work, we have synthesized the polysaccharide-based MIMs for separation, electerochemical sensing, fluorescent detection, drug delivery and catalyzing. The resultant MIMs were characterized by Fourier transform infrared spectroscope (FTIR), scanning electron micrographs (SEM) and thermogravimetric analyzer (TG/DTG), and their properties were also explored.The innovative points in this work are as follows. (1) Molecularly imprinted starch-based hydrogels for protein separation were prepared by enzymatic cross-linking technique. (2) Novel molecularly imprinted starch-based microgels with superparamagnetism and thermosensitivity were prepared for tyrosine separation. (3) Molecularly imprinted hybrid membranes as electerochemical sensors were prepared by a sol-gel process, using chitosan andβ-cyclodextrin-isocyanatopropyltriethoxysilane conjugate as main materials. (4) Molecularly imprinted hydrogels used as both the recognition and measuring elements for fluorescent assay were prepared. (5) Molecularly imprinted microgels with drug delivery effect and esterase activity were synthesized by a reverse emulsion method.The following results were obtained from this work.(1) Molecularly imprinted starch-based hydrogels for protein separationMolecularly imprinted hydrogels (MIHs) for bovine serum albumin (BSA) separation were prepared by an enzymatic cross-linking technique, using carboxymethylstarch-aminophenol conjugate (CMS-AP) as the functional macromonomer. Circular dichroism analysis showed that the conformation of BSA could be maintained after interacting with CMS-AP. The hydrogels were characterized by FTIR and SEM. Rheological analysis showed that the storage modulus of MIHs was dependent on the concentration and content of aminophenol group on CMS-AP. Adsorption experiments revealed that the adsorption capacity of MIHs was much higher than that of non-MIHs. Adsorption isotherm of MIHs followed Langmuir equation. The maximum BSA adsorption for both non-MIHs and MIHs was observed at pH 5.0. The selectivity of MIHs was greatly influenced by the template amount and the content of aminophenol group on CMS-AP.(2) Molecularly imprinted starch-based microgels with superparamagnetism and thermosensitivity for tyrosine separationMolecularly imprinted microgels with superparamagnetism and thermosensitivity (MMIGs) for tyrosine separation were prepared by a dispersion polymerization using carboxymethyl starch-aminopyridine conjugate as the functional macromonomer. The composition of the microgels was determined by TG/DTG analysis. X-ray diffraction (XRD) analysis revealed that imprinting process did not lead to the phase change of Fe3O4. SEM analysis showed that the particle size distribution of MMIGs was from 100 to 500 nm. The recognition sites in MMIGs were confirmed by FTIR. Magnetic measurement revealed that the MMIGs were superparamagnetic. Adsorption behavior of MMIGs could be described by the Langmuir equation. Temperature and medium pH were found to have great influence on the adsorption of MMIGs for tyrosine. Selectivity of MMIGs increased with the increase of the template or cross-linker amount.(3) Molecularly imprinted hybrid membranes based on chitoasn as electerochemical sensorsMolecularly imprinted hybrid membranes (MIMs) as electerochemical sensors were prepared by a sol-gel process, using chitosan andβ-cyclodextrin- isocyanatopropyltriethoxysilane conjugate (CD-IPTS) as the main materials. 1H NMR analysis revealed that inclusion complexes between CD-IPTS and tyrosine were formed. The recognition sites were confirmed by FTIR. Adsorption behavior of MIMs could be described by the Langmuir equation. The amounts ofγ-glycidoxypropyltrimethoxysilane (GPTMS) and template were found to have a great influence on the selectivity of MIMs. Electrochemical measurements showed that the response current of electrode modified by MIMs was obviously higher than that of the electrode modified by non-MIMs. The response current was influenced by medium pH, and the amounts of GPTMS and template. A highly linear response with a linear correlation coefficient of 0.998 to tyrosine was observed in the concentration range of 10-80μg/mL. (4) Molecularly imprinted starch-based hydrogels for fluorescent assayFluorescent molecularly imprinted hydrogels (MIGs) used as both the recognition and measuring elements for fluorescent assay were prepared by using maleic anhydride esterified starch-aminoquinoline conjugate as the functional macromonomer. The morphology and size of gels were characterized by SEM and Malvern particle size anylyzer. The adsorption process of theophylline to MIGs could be described by Lagergren first-order equation. The amounts of template and cross-linker were found to have a great influence on the selectivity of MIGs. Scatchard analysis indicated that the MIGs exhibited high affinity and good selective binding of theophylline relative to its analog caffeine. Dramatic quenching of fluorescence was observed when MIGs was re-exposed to theophylline. The ratio (Io/I) of fluorescence intensities in the absence of theophylline to fluorescence intensities in the presence of theophylline could reach 1.25. A highly linear response with a linear correlation coefficient of 0.993 to theophylline was observed in the concentration range of 0-200μg/mL.(5) Molecularly imprinted magenetic microgels based on chitosan for controlled release of drugMolecularly imprinted microgels (MMIGs) with superparamagnetism for controlled release of drug have been prepared by a reverse emulsion method, using carboxymethyl chitoan as the functional macromonomer. The contents of modified Fe3O4 in microgels were determined by TG/DGT. FTIR and photoluminescence spectra of microgels confirmed the presence of the recognition sites. XRD analysis revealed that coating process did not lead to the phase change of Fe3O4. SEM analysis showed that the particle diameters of MMIGs were about 1-5 um. Magnetic measurement revealed that the resultant MMIGs were superparamagnetic. Release rate of caffeine from MMIGs was much slower than that of caffeine from non-MMIGs. The release rate was influenced by the amounts of template, cross-linker and loading. Release behavior of caffeine from MMIGs could be described by Peppas equation. The release mechanism changed from a Case II transport to non-Fickian diffusion due to the effect of magnetic field. The release test of theophylline from MMIGs exhibited an inherent selectivity to caffeine.(6) Molecularly imprinted dextran-based microgels with thermosensitivity and esterase activityTemperature-sensitive molecularly imprinted microgels (MIGs) exhibiting esterase activity were prepared by a reverse emulsion method using dialdehyde dextran-histidine conjugate as the functional macromonomer. The interaction between functional group and the template was studied by UV spectrophotometer. SEM analysis revealed that well-shaped microgels with the diameter ranging from 200 to 500 nm were obtained. The obtained MIGs showed high catalytic activity to the hydrolysis of p-nitrophenyl acetate (NPA), which was influenced by medium pH value and temperature. The hydrolysis kinetics of NPA in the presence of MIGs could be described by the Michaelis-Menten equation. The Michaelis-Menten constant and maximium velocity were found to be 2.2×10-5 mol/L and 2.04×10-8 mol/h, respectively. In addition, the MIGs were found to have a high catalytic selectivity to NPA.更多还原