三聚氰胺分子印迹聚合物的理论设计与制备

发布时间：2018-02-09 14:50

  本文关键词： 三聚氰胺 分子印迹聚合物 计算模拟 功能单体 交联剂 溶剂　出处：《吉林农业大学》2016年硕士论文　论文类型：学位论文

【摘要】：三聚氰胺(Melamine,MAM)是一种高含氮量的有机化工原料,主要用于生产胶黏剂、胶水、层压板等。其加入到食品中可提高蛋白质的表观含量,对人类健康造成严重威胁。近几年,发生在国内外婴儿奶粉受MAM污染导致肾结石事件使MAM的检测成为研究的热点。因此,如何从食品中快速、准确且低成本地分离、纯化MAM目标待测物,对提高其检验方法的灵敏度及准确度具有重要的意义。分子印迹技术是以某一特定的目标分子为模板(印迹)分子,制备对该分子有特异选择性识别的分子印迹聚合物(Molecularly imprinted polymers,MIPs)的过程。MIPs具有较好的理化稳定性、构效预定性和特异识别性,在固相萃取、色谱分离、传感器、催化剂等诸多领域展现了良好的应用前景。其制备受功能单体、印迹反应比例、溶剂及交联剂等诸多因素的影响,为提高MIPs对印迹分子的亲和性、选择性和识别性,计算机辅助模拟被广泛地应用于优化分子印迹体系。本研究借助Gaussian 09软件,分别选用B3LYP、PBE1PBE、LC-wPBE和WB97XD四种密度泛函理论方法与两种基组(6-31G(d,p)、6-31+G(d,p))优化MAM印迹分子。结果表明,WB97XD/6-31G(d,p)方法更适合三聚氰胺分子印迹聚合物(MAM-MIPs)的理论研究。然后以WB97XD/6-31G(d,p)为计算方法,MAM为印迹分子,丙烯酰胺(Acrylamide,AM)、甲基丙烯酸(Methacrylic acid,MAA)、N,N-亚甲基双丙烯酰胺(N,N'-Methylenebisacrylamide,MBA)、衣康酸(Itaconic acid,IA)及三氟甲基丙烯酸(Trifluoromethylacrylic acid,TFMAA)为功能单体,二乙烯基苯(Divinylbenzene,DVB)、乙二醇双甲基丙烯酸酯(Ethylene Glycol Dimethacrylate,EGDMA)、三羟甲基丙烷三甲基丙烯酸酯(Trimethylolpropane Trimethylacrylate,TRIM)和季戊四醇三丙烯酸酯(Pentaerythritol triacrylate,PETA)为交联剂,模拟并探讨MAM与五种功能单体间的成键作用位点、成键数目、印迹反应摩尔比例及印迹作用机理,依据结合能(△E)优化功能单体和交联剂,溶剂化能筛选印迹体系的最佳溶剂,并借助分子中的原子理论(Atoms In Molecules,AIM)与红外光谱揭示MAM与功能单体印迹作用的本质。计算结果表明:MAM通过氢键与功能单体进行印迹聚合,其中IA作为功能单体与印迹分子形成的复合物结合能最低,结构最稳定,且最佳反应摩尔比例为1:6;DVB与MAM结合能最低,更适合作为MAM-MIPs的交联剂。在甲醇(Methanol,MT)溶剂中有望合成对MAM印迹分子识别与选择能力较强的MIPs。在MAM-MIPs稳定复合物构型的基础上去除印迹分子MAM,并固定剩余原子,在对应位置分别插入MAM结构类似物环丙氨嗪(Cyromazine,CYR)、三聚氰酸(Cyanuric acid,CYA)、三聚硫氰酸(Trithiocyanuric,TRI)分子作为底物,通过再结合能来预测MIPs对MAM的亲和性和选择性。结果表明,MAM-MIPs对MAM印迹分子展现出良好的选择吸附性。依据理论计算结果,采用沉淀聚合法合成一系列不同功能单体、交联剂、印迹摩尔比例、溶剂的MAM-MIPs,测定其吸附量并进行表征。实验结果表明,与AM、MAA、MBA、TFMAA相比,IA作为功能单体,且印迹摩尔比例为1:6时形成的MAM-MIPs复合物结合能最低,结构最稳定;与EGDMA、TRIM、PETA交联剂相比,DVB与MAM结合能最低,更适合作为MAM-IA印迹聚合物的交联剂。在MT溶剂中制得的MAM-MIPs纳米微球形貌较好,呈规则的球形,平均粒径为195 nm。Scatchard分析结果表明,在研究浓度范围内MIPs对印迹分子MAM的结合位点是等价的,其最大表观吸附量Qmax为20.79 mg/g,离解平衡常数Kd为58.82 mg/L;与CYR、CYA、TRI的吸附量相比,MAM-MIPs对MAM表现出较强的特异吸附能力。最后,在纯牛奶样品中添加一定量的MAM,将本研究所制得的MAM-MIPs作为吸附材料对奶制品中的MAM进行富集分离,其回收率高达99.41%。本研究为MAM-MIPs作为分离吸附剂选择性分离和检测奶制品中的MAM提供了依据。
[Abstract]:Melamine (Melamine, MAM) is a kind of high nitrogen content of organic chemical raw materials, mainly used in the production of adhesive, glue, laminated plate. It is added to food can increase the apparent protein content, poses a serious threat to human health. In recent years, in the domestic and foreign infant formula contaminated by MAM lead the kidney stone event has become a research hotspot of MAM detection. Therefore, how to quickly and accurately from the food, low cost, separation, purification of MAM target, to improve the test sensitivity and has important significance for accuracy. Molecular imprinting technique is based on a specific target molecule (imprinted as template) molecules, preparation of molecularly imprinted polymer specific and selective recognition of the molecule (Molecularly imprinted, polymers, MIPs) of.MIPs has good physical and chemical stability, structure-activity and predetermined specificity, in solid phase extraction, color Spectrum separation, sensor, catalyst and other fields show a good application prospect. The prepared functional monomer, blotting ratio, solvent effects of crosslinking agent and other factors, in order to improve the MIPs of molecular imprinting affinity, selectivity and recognition, computer aided simulation is widely applied to the optimization of molecular imprinting system this study with Gaussian 09 software, respectively by B3LYP, PBE1PBE, LC-wPBE and WB97XD four kinds of density functional theory and two kinds of basis set (6-31G (D, P), 6-31+G (D, P) MAM) to optimize the imprinted molecule. The results showed that WB97XD/6-31G (D, P) method is more suitable for melamine molecularly imprinted polymer (MAM-MIPs) theory. Then based on the WB97XD/6-31G (D, P) for the calculation method of MAM as the template molecule, acrylamide (Acrylamide, AM), methacrylic acid (Methacrylic acid, MAA), N, N- methylenebisacrylamide (N, N'-Methylenebisacrylamide, MBA Itaconic acid (Itaconic), acid, IA) and three fluorine (Trifluoromethylacrylic acid, TFMAA methacrylate) as functional monomers, two vinyl benzene (Divinylbenzene, DVB), ethylene glycol dimethacrylate (Ethylene Glycol, Dimethacrylate, EGDMA), three hydroxymethyl propane three methyl acrylate (Trimethylolpropane Trimethylacrylate, TRIM) and pentaerythritol three acrylate (Pentaerythritol triacrylate, PETA) as crosslinking agent, and to explore the role of key sites of MAM simulation and five kinds of functional monomer into the bonding reaction and the molar ratio of the number of Western blot mechanism, on the basis of energy (E) optimization of functional monomer and crosslinker and solvation energy is the best solvent screening imprinting system, and using the theory of atoms in molecules (Atoms, In Molecules, AIM) and infrared spectra revealed that the MAM and functional monomer for imprinting nature. The calculation results show that the MAM by hydrogen bonding and power Can the monomer imprinting polymerization which complex formation of IA monomer and imprinted molecules as a function of the binding energy of the lowest, the most stable structure, and the optimum molar ratio of 1:6; DVB and MAM with the lowest, more suitable as a crosslinking agent in methanol. MAM-MIPs (Methanol, MT) solvent to synthesis of MAM imprinted molecule identification and selection ability of MIPs. based on MAM-MIPs stable complex configuration on the removal of imprinted molecule MAM, and fixed the remaining atoms, are respectively inserted into the corresponding position in the MAM structural analogs of cyromazine (Cyromazine, CYR), cyanuric acid (Cyanuric, acid, CYA, Trithiocyanuric acid (Trithiocyanuric). TRI) molecules as substrate, to predict the MIPs of MAM affinity and selectivity by binding energy. The results showed that MAM-MIPs of MAM imprinted molecules show selective adsorption well. According to the theoretical calculation results, synthesized by precipitation polymerization 绯诲垪涓嶅悓鍔熻兘鍗曚綋,浜よ仈鍓，

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