摘要
生物碱是中草药中重要的有效成分,不同生物碱具有不同的药理活性。但是从中草药中提取纯化生物碱,是一项十分复杂的生物活性成分提取工程,通常所用的溶剂萃取分离法,效率低成本又高。本研究采用本课题组建立的新型表面印迹技术,分别制得了苦参碱印迹材料与金雀花碱印迹材料,并探讨了它们对模板分子的结合特性与机理,为将分子表面印迹材料应用于生物碱的分离提纯进行了探讨性研究,本文的研究结果对于提升生物碱分离纯化技术水平具有重要的科学意义与价值。
本文首先通过偶联剂γ-(2,3-环氧丙氧)丙基三甲氧基硅烷(EPPS)的媒介,以硫酸铈铵为引发剂,在酸性溶液聚合体系中实施了丙烯腈(AN)在硅胶表面的接枝聚合,制备了接枝微粒PAN/SiO_2。以硫酸为试剂,进行了接枝聚丙烯腈PAN的酸性水解,制得了接枝有聚丙烯酸(PAA)的功能微粒PAA/SiO_2。重点考察了各主要因素对AN的接枝聚合过程及对PAN酸性水解的影响规律。研究结果表明,在接枝聚合过程中,采用适宜的引发剂用量与反应温度,PAN的接枝度可达19g/100g。影响PAN/SiO_2酸性水解的主要因素为介质的pH值与温度。在适宜条件下,腈基转化率才能达到50%。显然,经聚丙烯腈接枝接枝PAN/SiO_2水解方法所制备的功能微粒PAA/SiO_2,PAA含量较低(虽然聚丙烯腈接枝效率高)。因此,本研究又采用在硅胶微粒表面直接接枝聚甲基丙烯酸(PMAA)的方法,制备了接枝微粒PMAA/SiO_2。在适宜的条件下,制得了接枝度为15.54 g/100g的PMAA/SiO_2,可大幅度提高对生物碱的吸附能力。
较深入地研究了接枝微粒PMAA/SiO_2对生物碱的吸附性能与机理。实验结果表明,PMAA/SiO_2对生物碱具有强的吸附作用,吸附的驱动力是氢键及静电相互作用两种作用协同的结果。在pH=9时,PMAA/SiO_2对苦参碱具有最大吸附量;在pH为10时,PMAA/SiO_2对金雀花碱具有最大吸附量。温度对吸附性能也有很大的影响,升高温度吸附量降低。
以苦参碱为模板分子,乙二醇二缩水甘油醚(EGDE)为交联剂,对接枝在硅胶表面的PMAA大分子链进行了分子交联,同时实现了苦参碱分子的表面印迹,制备了苦参碱分子表面印迹材料MIP-PMAA/SiO_2。采用静态与动态两种方法研究了MIP-PMAA/SiO_2对苦参碱的结合性能与分子识别特性。实验结果表明,印迹材料MIP-PMAA/SiO_2对苦参碱具有特异的识别选择性与优良的结合亲和性,相对于对比物金雀化碱,印迹之前,PMAA/ SiO_2对苦参碱的吸附选择系数仅为0.95,而印迹之后,分子印迹材料MIP-PMAA/ SiO_2的吸附选择系数则提高至8.14。此外,印迹材料MIP-PMAA/SiO_2具有良好的洗脱性能。
最后,以金雀花碱为模板分子,乙二醇二缩水甘油醚为交联剂,在PMAA/SiO_2表面上的PMAA进行交联反应,同时实现了金雀花碱分子的表面印迹,成功地制得了金雀花碱分子表面印迹材料MIP-PMAA/SiO_2。采用静态与动态两种方法研究了MIP-PMAA/SiO_2对金雀花碱的结合性能与分子识别特性。实验结果表明,MIP-PMAA/SiO_2对金雀花碱具有特异的识别选择性与优良的结合亲和性。相对于参比物苦参碱,PMAA/ SiO_2对金雀花碱的识别选择系数仅为1.06,而表面印迹材料MIP- PMAA/ SiO_2的识别选择系数则提高至12.08;相对于参比物氧化苦参碱,PMAA/ SiO_2对金雀花碱的识别选择系数仅为1.03,而表面印迹材料MIP- PMAA/ SiO_2的识别选择系数则提高至15.05。同时金雀花碱印迹材料MIP-PMAA/SiO_2的洗脱性能良好。
Alkaloid is the main active ingredient contained in Chinese herbal medicine and the various alkaloids have different pharmacological activities. But it is very complicated to purify the alkaloid. This paper investigates the synthesis of novel adsorption materials for matrine and cytisine, and researches the adsorption character and mechanism. The experimental results have important reference values for separating alkaloid.
Firstly, via the coupling effect of 2, 3-glycidoxypropyltrimethoxysilane (EPPS), the graft polymerization of acrylonitrile on the surface of silica gel particles was performed in an acidic solution polymerization system by using cerium ammonium sulfate as initiator, and grafted microspheres PAN/ SiO_2 were prepared. The transform reaction of nitrile groups of the grafted PAN to carboxylic groups (AA) was conducted with vitriol as reagent in the presence of H2O, resulting in functional composite-type particles PAA/SiO_2, on which poly (acrylic acid) macromolecules were chemically anchored. The experimental results show that in the graft polymerization process, the grafting degree of PAN can get up to 19g/100g by controlling the used amount of initiator and temperature. The conversion ratio of the nitrile groups is affected greatly by the pH value of the medium and temperature. Under the appropriate conditions, the functional particles PAA/SiO_2 with a nitrile group conversion ratio of 50% can be obtained. This means that the content of PAA on the surface of the functional particles PAA/ SiO_2 is lower. Therefore, grafted microspheres PMAA/ SiO_2 were prepared by grafting from on the surface of the silicon. The adsorption capacity of PMAA/SiO_2 for alkaloid in water is largely improved.
The adsorption capacity and adsorption mechanism of PMAA/SiO_2 for alkaloid in water is further studied. The experimental results show that the grafted particle PMAA/SiO_2 has strong adsorption ability for alkaloid. The driving force of the adsorption is the synergism of electrostatic and hydrogen bond interaction. The adsorption capacity has a maximum value at pH=9 for matrine and pH=10 for cytisine. The reaction temperature can exert great effect on the adsorption property of PMAA/SiO_2, and the adsorption capacity is decreased with the increase of the temperature.
Then, the molecular imprinting towards the grafted PMAA was performed with alkaloid matrine as template molecule and ethylene glycol diglycidyl ether (EGDE) as crosslinking agent, and the matrine molecule-imprinted material MIP-PMAA/SiO_2 was prepared. Both static and dynamic methods were adopted to study the binding properties and molecule recognition character of MIP-PMAA/SiO_2 for matrine. The experiment results show that MIP-PMAA/SiO_2 possess strong recognition capability for matrine. In relation to cytisine, the selectivity coefficient of PMAA/SiO_2 for matrine is 0.95, and that of MIP-PMAA/SiO_2 for matrine is 8.14. Besides, MIP-PMAA/SiO_2 has excellent elution property.
Finally, MIP-PMAA/SiO_2 was prepared with cytisine as a template molecule and EGDE as crosslinking agent, and by right of the intermolecular hydrogen bond and electrostatic interactions between the grafted PMAA macromolecules and cytisine molecules. Both static and dynamic methods were adopted to study the binding properties and molecule recognition character of MIP-PMAA/SiO_2 for cytisine. The experiment results show that MIP-PMAA/SiO_2 possess strong recognition capability for cytisine. In relation to matrine, the selectivity coefficient of PMAA/SiO_2 for cytisine is 1.06, and that of MIP-PMAA/SiO_2 for matrine is 12.08, and in relation to oxymatrine, the selectivity coefficient of MIP-PMAA/SiO_2 for cytisine is increased from 1.03 to 15.05. Besides, MIP-PMAA/SiO_2 has excellent elution property.
引文
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