Improved Method of Molecular Imprinting of Cyclodextrin on Silica-gel Surface for the Preparation of Stable Stationary HPLC Phase

By using N-(3-triethoxysilyl)propylacrylamide (TPAAm), vinyl groups were introduced onto the surface of silica-gel. On the surface of this silica-gel, β-CyD was molecularly imprinted by using a redox initiator, and the composite was used as stationary phase of high performance liquid chromatography (HPLC). The pump pressure was sufficiently low and did not increase even after continuous elution for 24 h. In order to prepare still more stable columns, a new polymerization process was developed. There, the redox initiator was first mixed with the surface-modified silica-gel and then vinylated β-CyD, crosslinker, and the template were added. This modification promoted the immobilization of β-CyD copolymer to the silica-gel, resulting in still lower pump pressure. Concurrently, the imprinting efficiency was increased in comparison with previous method where the redox initiator was directly added to the mixture of the β-CyD–template complex, crosslinker, and surface-modified silica-gel. The molecularly imprinted β-CyD column, prepared by this new method, efficiently discriminated the enantiomers of N-benzyloxycarbonyltyrosine.     

Magnetic Core-Shell Nanoparticles Using Molecularly Imprinted Polymers for Zearalenone Determination

This paper describes the synthesis of novel molecularly imprinted magnetic nano-beads for the selective extraction (MISPE) of zearalenone mycotoxin in river and tap waters and further analysis by high-performance liquid chromatography (HPLC) with fluorescence detection (FLD). A semi-covalent imprinting approach was achieved for the synthesis of the molecularly imprinted polymers (MIP). The nanoparticles were prepared by covering the starting Fe₃O₄ material with a first layer of tetraethyl orthosilicate (TEOS) and then with a second layer using cyclododecyl 2-hydroxy-4-(3-triethoxysilylpropylcarbamoyloxy) benzoate. The last was used with a dual role, template and functional monomer after the extraction of the template molecule. The material was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopies (FT-IR). The solid phase extraction was optimized in all the steps: loading, washing and elution. The optimal conditions allowed the determination of zearalenone in trace levels of 12.5, 25 and 50 µg L⁻¹ without significant differences between the fortified and found level concentrations.     

Smart Molecularly Imprinted Polymers: Recent Developments and Applications

The use of the molecular imprinting technique to produce polymers with high specificity for a given “molecular template” has undergone a rapid and expansive evolution since the inception of the idea over half a century ago. It was only a matter of time before the seemingly inevitable “marriage” of this concept with another modern research obsession, the generation of “smart” polymers, capable of reacting quickly, accurately and reproducibly to changes in their environment. Many advances have since been made, concerning the quality and diversity of these systems and polymers responsive to temperature, pH and a host of other environmental cues now exist. This article provides a succinct overview of the process and outcomes of “smart” molecular imprinting, followed by a detailed assessment of recent developments and applications in such field.

     

Chromatographic Properties for Enantiomeric Separation of Amino Acid Derivatives on the Molecularly Imprinted Monoliths

Since their introduction in 1992 by Fréchet and Svec[1], monolithic supports as stationary phases in high performance liquid chromatography (HPLC) and capillary electrochromatography (CEC) have gained significant interest due to a number of unique properties. Their ease of preparation, high reproducibility, versatile surface chemistry and fast mass transport are advantageous in a variety of applications[2-4]. Separations in diverse chromatographic modes have been performed in either HPLC or CEC, showing their strong point for high-speed separations of biological and synthetic molecules[5-12]. Although a number of papers have been reported on the application of monolithic supports as chiral stationary phases in CEC and pressure-assisted capillary electrochromatography (p-CEC)[13-19], few reports have so far been published on chiral monolithic stationary phases for liquid chromatography[20].     

Selective Preconcentration of Mezlocillin from Eggs by Molecularly Imprinted Polymers on Silica

Surface molecularly imprinted polymers for mezlocillin were used for the selective solid-phase extraction of mezlocillin from eggs. The molecularly imprinted polymers were prepared using mezlocillin as the template, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, silica particle as the support and were characterized by infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The adsorption properties of polymers were investigated in detail. The obtained polymers provided high imprinting efficiency to mezlocillin with an imprinting factor of 3.72 and were used as selective sorbents for mezlocillin. Molecularly imprinted solid-phase extraction followed by high-performance liquid chromatography was used for the determination of mezlocillin in eggs and the conditions were evaluated. The average recovery of mezlocillin in fortified eggs was between 69.8 and 82.3% with a relative standard deviation less than 6.9%. The results demonstrate the application of molecularly imprinted polymers for the extraction of mezlocillin from biological samples.     

分子印迹聚合物研究:从小分子到生物大分子

分子印迹技术是一项制备功能聚合物材料的方法,其对印迹分子的专一性选择识别能力引起了人们的广泛关注。随着方法的基本确立和技术的逐渐成熟,其应用领域和范围不断扩大。本文在总结以往研究结果的基础上,对迄今为止进展相对缓慢的生物大分子印迹研究予以了特别关注,对相关的水环境下的分子识别问题进行了仔细的讨论,认真的分析了生物大分子印迹研究工作的难点和不利因素,对分子印迹技术的未来发展和应用前景进行了展望。     

分子印迹聚合物微球的制备及应用研究进展

球形分子印迹聚合物具有制备简单、使用方便；分子识别效率高且便于功能设计等优点，近年来成为分子印迹技术领域研究的热点之一。对球形分子印迹聚合物微球的制备及其应用研究进展作了较为详细的介绍。     

Binding Studies on Substrate- and Enantio-Selective Molecularly Imprinted Polymers

Abstract

A molecularly imprinted polymer was prepared using tert-butyloxycarbonyl-L-phenylalanine as the print molecule and methacrylic acid as the functional monomer. The bulk polymer obtained was ground, sieved, packed into a column and investigated in the HPLC-mode by frontal chromatography to determine the number of binding sites and dissociation constants for the enantiomers interacting with the polymer. The dissociation constant for the L-enantiomer of the print molecule was lower than for the D-enantiomer (6.3 mM and 8.1 mM, respectively). This means that the affinity for the L-enantiomer was higher than for the D-enantiomer. The number of binding sites in the polymer giving rise to these dissociation constants were determined to be 28 μmol per g dry polymer.     

磺酰脲类除草剂分子印迹聚合物制备及应用研究进展

磺酰脲类除草剂本身易降解,在环境和生物样品中痕量存在,其残留分析工作颇具挑战。分子印迹聚合物因其良好的选择性和稳定性已被广泛应用于农药残留分析的分离与富集前处理过程,提高了检测的准确度和精密度。本文从单体、溶剂与致孔剂、聚合方法三个方面概述了近15年来磺酰脲类分子印迹聚合物的制备,并对其在残留检测中的应用方式进行了综述,为磺酰脲类除草剂残留检测技术的进一步开发提供了参考。     

Molecularly Imprinted Nanospheres by Nonaqueous Emulsion Polymerization

The preparation of nanosized, molecularly imprinted polymer particles by nonaqueous emulsion polymerization is presented. Monodisperse cross‐linked polymer nanospheres with a diameter of around 100 nm were synthesized using a standard monomer mixture of methacrylic acid and ethylene dimethacrylate, containing (±)‐propranolol as a template. The rebinding efficiency of the resulting particles was determined by batch rebinding tests and isothermal titration calorimetry (ITC). The results indicate that the proposed imprinting process under nonaqueous conditions lead to particles with an enhanced capacity of template rebinding compared to both nonimprinted ones and to particles obtained by more conventional emulsion polymerization in water.

     

Molecular Imprinting of Cyclodextrin on Silica-Gel Support for the Stationary Phase of High-Performance-Liquid-Chromatography

By copolymerizing acryloyl cyclodextrin (CD) andN,N'-methylenebisacrylamide with vinylated silica-gel in the presence of a template in water,a thin layer of molecularly imprinted CD polymer was immobilized on a porous silica-gel support. This mechanically weak polymer was reinforced by the silica-gel andsuccessfully used as a stationary phase in high-performance-liquid-chromatography (HPLC). When L-Phe-L-Phe was the template, the polymer/silica-gel conjugate retainedL-Phe-L-Phe in the aqueous eluent more strongly than D-Phe-D-Phe. As expected, the D-Phe-D-Phe-imprinted polymer retained D-Phe-D-Phe more strongly than L-Phe-L-Phe. Selective separation of antibiotics was also achieved by thepolymer/silica-gel conjugate. Molecularly imprinted CD polymer, immobilizedon silica-gel, is an eminent stationary phase for HPLC in water.     

沉淀聚合法合成拟除虫菊酯类分子印迹聚合物及其吸附性能研究

采用沉淀聚合法,以拟除虫菊酯的结构类似物二苯醚-联苯共晶作为替代模板,优化得到最佳的拟除虫菊酯类分子印迹聚合物合成条件:模板分子(二苯醚-联苯共晶)、功能单体(4-乙烯吡啶)、交联剂(乙二醇二甲基丙烯酸酯)的摩尔比为1∶6∶20,反应温度为70℃,引发剂用量为1%。将合成的分子印迹聚合物通过扫描电镜进行表征,并对吸附性能进行测试,其对60μg·mL~(-1)的二苯醚-联苯共晶的最大吸附量为6 041μg·g~(-1),且在7 h后达到吸附平衡。通过选择性实验得到印迹聚合物对毒死蜱、联苯菊酯、甲氰菊酯、氯菊酯、氯氰菊酯、氰戊菊酯的吸附量分别为259、316、311、271、305、298μg·g~(-1),而非印迹聚合物的吸附量则为169、188、181、183、151、142μg·g~(-1),印迹聚合物的选择性能明显高于非印迹聚合物。     

除草剂青莠定分子印迹聚合物的合成及结合性能研究

采用分子印迹技术,分别以α-甲基丙烯酸和4-乙烯基吡啶为功能单体,合成了两种对除草剂青莠定具有选择性结合能力的分子印迹聚合物．紫外光度法研究显示了模板分子青莠定和4-乙烯基吡啶的离子作用强于它和α-甲基丙烯酸之间的氢键作用,并用平衡结合实验研究了不同功能单体的聚合物对模板分子的结合能力和对底物的选择性,结果表明以4-乙烯基吡啶为功能单体合成的分子印迹聚合物对青莠定表现出更高的结合能力和更优的选择性．这对分子印迹技术用于环境样品中除草剂青莠定的分离和富集具有重要意义。     

芦丁-槲皮素双模板印迹聚合物的制备、表征及识别

以芦丁(RT)-槲皮素(QT)为混合模板分子制备了芦丁-槲皮素复合模板分子印迹聚合物。 优化了制备条件,研究了模板用量比、功能单体及交联剂用量对印迹聚合物吸附性能的影响。 用傅里叶红外光谱和扫描电镜对分子印迹聚合物进行结构表征。 探讨了分子印迹聚合物的吸附动力学、等温吸附及键合位点特征,考察了其选择识别性能,并以分子印迹聚合物为吸附介质,萃取分离芦丁粗提液中的目标化合物。 结果表明,当槲皮素与芦丁的摩尔比为3:2,且模板总量与功能单体及交联剂用量摩尔比为1:8:10时,所得分子印迹聚合物的吸附性能最好,对槲皮素和芦丁的吸附量分别达47.86和60.97 mg/g。 吸附可在3.5 h内达到平衡,显示了较快的吸附动力学。 Scatchard分析表明,分子印迹聚合物基体中存在四类不同性能的键合位点,分别为芦丁和槲皮素的高亲和键合位点及非选择键合位点。 相对分布系数(k=K_d(RT)/K_d(QT),K_d=q_e/ρ_e,K_d为分布系数,q_e为平衡吸附量,ρ_e为平衡质量浓度)大于1,表明了分子印迹聚合物对芦丁具有更高的选择键合作用,当模拟混合物中芦丁和槲皮素浓度分别为0.07和0.03 mmol/L时,相对分布系数和分离因子(α=q_e(RT)/q_e(QT))分别达6.669和25.02。 另外,以乙腈、甲醇及甲醇-醋酸混合物依次为洗脱剂,通过分子印迹固相萃取可从槐米提取物中分离芦丁和槲皮素两种黄酮类化合物,总回收率分别为96.70%和94.67%。     

Molecularly Imprinted Polymers: Compromise between Flexibility and Rigidity for Improving Capture of Template Analogues

New synthetic strategies for molecularly imprinted polymers (MIPs) were developed to mimic the flexibility and mobility exhibited by receptor/enzyme binding pockets. The MIPs were prepared by bulk polymerization with quercetin as template molecule, acrylamide as functional monomer, ethylene glycol dimethacrylate as cross‐linker, and THF as porogen. The innovative grafting of specific oligoethylene glycol units onto the imprinted cavities allowed MIPs to be obtained that exhibit extended selectivity towards template analogues. This synthetic strategy gives promising perspectives for the design of molecular recognition of molecules based on a congruent pharmacophore, which should be of interest for drug development.     

核-壳型分子印迹聚合物的制备与应用

分子印迹聚合物是具有与模板分子形状、大小及官能团完全匹配的特异识别位点的高分子聚合物,能选择性识别、有效富集目标分析物(模板分子)并去除干扰物,已广泛应用于样品前处理、化学/生物传感、药物输送等领域.然而,在合成过程中,仍存在模板分子洗脱困难、有效识别位点少、结合容量低、传质速率慢等问题.核-壳型分子印迹聚合物即在核层颗粒表面进行分子印迹,即表面印迹,印迹位点仅存在于壳层结构中,利于模板分子洗脱及扩散,能够增加有效识别位点并提高印迹容量.依据核层材料的不同,本文详细介绍了以磁性材料及非磁性材料为核的核-壳型分子印迹聚合物的合成与应用,探讨了中空核-壳分子印迹聚合物的制备与发展,并对核-壳印迹聚合物的发展前景进行了展望.     

A Molecularly Imprinted Nicotine-Selective Polymer

Abstract

A (-)-nicotine-selective polymer was prepared by molecular imprinting technique using methacrylic acid as a functional monomer. Liquid-chromatographic tests, using the polymers as a stationary phase, exhibited that the basicity of the functional group of (-)-nicotine is crucial for rebinding by the molecularly imprinted polymer. Scatchard analysis implied that the binding sites generated within the polymer are heterogeneous in terms of affinity, and the apparent dissociation constant of the highest affinity binding sites was estimated as 3.7 μM.     

原位聚合法制备氨基安替比林分子烙印聚合物及分离特性的研究

以氨基安替比林为模板分子,采用原位聚合法制备了具有特定识别性能的棒状分子烙印聚合物。通过考察烙印分子的化学基团对分离的影响,以及离子作用和氢键作用在分离中的贡献,论证了分子烙印聚合物选择性专一的作用机理。结果表明,这种棒状聚合物对模板分子及其类似物有很好的分离能力。     

高效液相色谱环糊精键合固定相

环糊精是由Ｄ（＋）－葡萄糖单元通过α－１，４糖苷键连接的环状齐聚糖，其最典型的性质是能与许多客体分子形成包容配合物。高效液相色谱环糊精键合固定相广泛用于对映异构体，非对映异构体，结构异构体和常规化合物的分离。     

An Update on the Use of Molecularly Imprinted Polymers in Beta-Blocker Drug Analysis as a Selective Separation Method in Biological and Environmental Analysis

Beta-blockers are antihypertensive drugs and can be abused by athletes in some sport competitions; it is therefore necessary to monitor beta-blocker levels in biological samples. In addition, beta-blocker levels in environmental samples need to be monitored to determine whether there are contaminants from the activities of the pharmaceutical industry. Several extraction methods have been developed to separate beta-blocker drugs in a sample, one of which is molecularly imprinted polymer solid-phase extraction (MIP-SPE). MIPs have some advantages, including good selectivity, high affinity, ease of synthesis, and low cost. This review provides an overview of the polymerization methods for synthesizing MIPs of beta-blocker groups. The methods that are still widely used to synthesize MIPs for beta-blockers are the bulk polymerization method and the precipitation polymerization method. MIPs for beta-blockers still need further development, especially since many types of beta-blockers have not been used as templates in the MIP synthesis process and modification of the MIP sorbent is required, to obtain high throughput analysis.