Synthesis of molecularly imprinted polymers for amino Acid derivates by using different functional monomers

Fmoc-3-nitrotyrosine (Fmoc-3-NT) molecularly imprinted polymers (MIPs) were synthesized to understand the influence of several functional monomers on the efficiency of the molecular imprinting process. Acidic, neutral and basic functional monomers, such as acrylic acid (AA), methacrylic acid (MAA), methacrylamide (MAM), 2-vinylpyridine (2-VP), 4-vinylpyridine (4-VP), have been used to synthesize five different polymers. In this study, the MIPs were tested in batch experiments by UV-visible spectroscopy in order to evaluate their binding properties. The MIP prepared with 2-VP exhibited the highest binding affinity for Fmoc-3NT, for which Scatchard analysis the highest association constant (2.49 × 10(4) M(-1)) was obtained. Furthermore, titration experiments of Fmoc-3NT into acetonitrile solutions of 2-VP revealed a stronger bond to the template, such that a total interaction is observed. Non-imprinted polymers as control were prepared and showed no binding affinities for Fmoc-3NT. The results are indicative of the importance of ionic bonds formed between the -OH residues of the template molecule and the pyridinyl groups of the polymer matrix. In conclusion, 2-VP assists to create a cavity which allows better access to the analytes.     

Fabrication of ordered microporous styrene‐acrylonitrile copolymer blend imprinted membranes for selective adsorption of phenol from salicylic acid using breath figure method

Highly selective, ordered microporous molecularly imprinted membranes (MIMs) for phenol were synthesized by breath figure (BF) method using styrene‐acrylonitrile copolymer (SAN) as the membrane matrix and molecularly imprinted polymer nanoparticles (nano‐MIPs) as the imprinted nanoparticles. The nano‐MIPs were synthesized by oil‐in‐water emulsion polymerization using 4‐vinyl pyridine (4‐VP), methyl methacrylate (MMA) or cinnamic acid (CA) as the functional monomer, respectively. The prepared nano‐MIPs were characterized by transmission electron microscope (TEM) and Raman, whereas MIMs were characterized by SEM, membrane flux, and selective adsorption experiments. Morphological analysis exhibited that the addition of nano‐MIPs improved the formation of ordered and well‐defined porous membrane morphology. Compared with MMA‐MIM and CA‐MIM, the 4‐VP‐MIM exhibited higher membrane flux, adsorption capacity, and stronger selective binding for phenol as well as excellent permeation selectivity for phenol. Moreover, the selective effect of 4‐VP‐MIM on phenol was strongly affected by the amount of 4‐VP imprinted nanoparticles (nano‐4‐VP‐MIPs). The experimental data revealed that the 4‐VP‐MIM containing 2.0 wt % of nano‐4‐VP‐MIPs exhibited the highest separation selectivity for the template phenol, whose selectivity coefficients for phenol relative to salicylic acid (SA) and p‐hydroxybenzoic acid (p‐HB) were 5.6770 and 5.5433, respectively, which was close to the predicted selectivity coefficient value. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42350.     

单体对分子印迹聚合物分子识别能力的影响：量子化学计算与实验研究

采用密度泛函方法计算功能单体与印迹分子的结合能,以与目标分子结合能最大的单体分子来合成分子印迹聚合物.为此,以茶碱为印迹分子,氯仿为溶剂,首先计算了茶碱与甲基丙烯酸、丙烯酰胺和三氟甲基丙烯酸的结合能,其强度顺序为：三氟甲基丙烯酸 > 甲基丙烯酸 > 丙烯酰胺.然后以茶碱为印迹分子、氯仿为溶剂、二甲基丙烯酸乙二醇酯为交联剂,分别采用上述3种单体合成分子印迹聚合物并测定了其分子识别能力,实验结果和量子化学计算结果具有一致性.最后,采用1H NMR考察了茶碱和上述3种单体之间的氢键作用,揭示出二者相互作用的内在机制.研究结果表明量子计算方法可以应用于合成分子印迹聚合物时单体的选择.     

二氯喹啉酸分子印迹聚合物微球的制备

采用改进的分散聚合方法制得的纳米级聚苯乙烯微球(PS)为种球,以二氯喹啉酸(quinclorac)为模板分子,通过单步溶胀聚合法在水相中制备了单分散分子印迹聚合物微球(MIPs)。通过红外光谱分析MIPs的结合位点;利用紫外光谱研究了MIPs的结合机理和识别特性;用扫描电镜观察了微球的形貌。结果表明,PS微球的粒径分布100～150nm,MIPs的粒径分布为200～300nm;Scatchard分析表明,MIPs在识别二氯喹啉酸过程中存在两类结合位点:高亲和性位点的解离常数KD1=0.0488mmol/L;低亲和性位点的解离常数KD2=0.423mmol/L。     

Precipitation polymerization of molecularly imprinted polymers for recognition of melamine molecule

Molecular imprinted polymer microspheres (MIPs) were prepared by precipitation polymerization using melamine as template molecule, methacrylic acid (MAA) as functional monomer, trimethylol‐propane trimethacrylate (TRIM) as crosslinking agent, acetonitrile as solvent and dispersion medium. Release of the template was performed by continuous extraction with methanol containing 10% acetic acid. The microspheres were observed by scanning electron microscopy (SEM). The perfect microspheres were produced when the addition of crosslinker was 7.48 mmol. The binding capacity of MIPs was examined, Q_max = 68.36 μmol g^?1, and the dissociation constant at binding site of MIPs, K_d = 0.761, was estimated. Compared with the performance of conventional imprinted polymer, the imprinted microspheres showed high selectivity in special binding to template molecule. The imprinted microspheres could be used as the stationary phase in HPLC or SPE for selective extraction of melamine in daily products. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Imprinted microspheres doped with carbon nanotubes as novel electroresponsive drug‐delivery systems

Novel molecularly imprinted polymers (MIPs) suitable for the electroresponsive release of diclofenac were synthesized by precipitation polymerization in the presence of carbon nanotubes (CNTs). Both conventional and electroresponsive imprinted polymers were synthesized with methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the crosslinker. Preliminary experiments were performed to fully characterize the conventional MIPs and composite materials in terms of their morphological properties, recognition behavior, and electric resistivity. In vitro release experiments were performed in aqueous media to elucidate the ability of the MIPs and spherical imprinted polymers doped with CNTs to release the loaded template in a sustained manner over time in comparison to the that of the corresponding nonimprinted materials. Furthermore, a 20‐V direct‐current voltage was applied through the releasing media to evaluate how the electric field influenced the drug release to demonstrate the suitability of the proposed macromolecular system as an electroresponsive drug‐delivery device. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 829‐834, 2013     

Molecularly imprinted polypyrrole prepared by electrodeposition for the selective recognition of tryptophan enantiomers

Herein we report the electrosynthesis of polypyrrole with L ‐tryptophan (L ‐Trp) as a template to prepare molecularly imprinted polymers (MIPs). Overoxidized polypyrrole films with cavities complementary to the template were used for the enantioselective detection of L ‐Trp and D ‐tryptophan (D ‐Trp). Important parameters, such as the electropolymerization potential, overoxidization potential and time, thickness of the polypyrrole films, and scanning rate of the stripping voltammetric experiments, were varied to achieve an optimum sensor response. We found that L ‐Trp was inserted about 2 times higher into the imprinted polymer film than D ‐Trp. Also, in this study, an electrochemical quartz crystal microbalance technique was used to investigate the performance of overoxidized polypyrrole films. The enantioselectivity of the MIPs was attributed to the cavities in the imprinted films, which were complementary to the target molecules, both in shape and in positioning of the functional groups. The results also suggest the feasibility of preparing MIPs by electropolymerization for the enantioselective recognition of other amino acid enantiomers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

To Remove or Not to Remove? The Challenge of Extracting the Template to Make the Cavities Available in Molecularly Imprinted Polymers (MIPs)

Template removal is a critical step in the preparation of most molecularly imprinted polymers (MIPs). The polymer network itself and the affinity of the imprinted cavities for the template make its removal hard. If there are remaining template molecules in the MIPs, less cavities will be available for rebinding, which decreases efficiency. Furthermore, if template bleeding occurs during analytical applications, errors will arise. Despite the relevance to the MIPs performance, template removal has received scarce attention and is currently the least cost-effective step of the MIP development. Attempts to reach complete template removal may involve the use of too drastic conditions in conventional extraction techniques, resulting in the damage or the collapse of the imprinted cavities. Advances in the extraction techniques in the last decade may provide optimized tools. The aim of this review is to analyze the available data on the efficiency of diverse extraction techniques for template removal, paying attention not only to the removal yield but also to MIPs performance. Such an analysis is expected to be useful for opening a way to rational approaches for template removal (minimizing the costs of solvents and time) instead of the current trial-and-error methods.     

Charged groups synergically enhance protein imprinting in amphoteric polyacrylamide cryogels

Proteins are amphoteric biopolymers with unevenly charged exterior surfaces. Taking this point fully into account could accomplish ingenious recognition systems for the biological macromolecues. Molecularly imprinted polymers (MIPs) are good tools to study the interactions between polymeric matrices and template molecules. Here different protein imprinted cryogels were prepared. Imprinting factors (IFs) were determined with bovine serum albumin (BSA) as the template. The IF of the polymeric cryogel made from only acrylamide (AM) and N,N′‐methylenebisacrylamide (BisAM) is about 1.38. The introduction of charged monomers, either acrylic acid or diallylamine, would increase IFs obviously. One of the basic cryogels gave the maximum IF (about 2.0) of that type. As both acrylic acid and diallylamine were involved, IFs were further increased. An amphoteric cryogel with a suitable acid‐base ratio gave a high IF of about 3.7. Whatever used alone or both, too many added acidic or basic monomers resulted in IF reduction. Taking full advantage of charged groups in MIPs could be a good way to manipulate protein–polymer interactions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43851.     

Preparation and characterization of uniform molecularly imprinted polymer beads for separation of triazine herbicides

Uniform molecularly imprinted polymer beads were synthesized by precipitation polymerization for separation of triazine herbicides. A series of imprinted polymers were prepared using ametryn as template and divinylbenzene as crosslinking monomer, in combination with three different functional monomers under different solvent conditions. Under optimized reaction conditions, we obtained uniform molecularly imprinted polymer microspheres that display favorable molecular binding selectivity for triazine herbicides. The imprinted polymer beads synthesized using methacrylic acid as functional monomer in a mixture of methyl ethyl ketone and heptane showed the best results in terms of particle size distribution and molecular selectivity. Compared with nonimprinted polymer microspheres, the imprinted microspheres displayed significantly higher binding for a group of triazine herbicides including atrazine, simazine, propazine, ametryn, prometryn, and terbutryn. For the first time, precipitation polymerization has been used to produce highly uniform imprinted microspheres suitable for affinity separation of triazine herbicides. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Uniformly sized molecularly imprinted polymers for on‐line concentration,purification, and measurement of nimodipine in plasma

Uniformly sized molecularly imprinted polymers (MIPs) for nimodipine have been prepared in an aqueous system by multi‐step swelling and polymerization method, utilizing 4‐vinylpyridine (4‐VPY) or methacrylic acid (MAA) as a functional monomer, ethylene glycol dimethacrylate (EDMA) as a cross‐linking agent. Scanning electron microscopy was used to identify the structure features of the obtained polymers. Further, the influences of some chromatographic conditions were examined to explore the possible recognition mechanism. The results reveal that stable molecularly imprinted polymeric microspheres with good size monodispersity were obtained, and the polymer beads showed specific recognition for the template molecule and some other dihydropyridine calcium antagonists (DHPs). Besides hydrophobic interaction, the molecular shape complementation of DHPs and the MIPs seems to play an important role in the retention and recognition of DHPs. The Scatchard analysis showed that two kinds of binding sites existed in the MIPs. The MIPs was then used as a high‐performance liquid chromatography (HPLC) separation medium to simultaneously concentrate and purify nimodipine in plasma. The results reveal that the obtained MIPs could be used for on‐line concentration, purification, and measurement of nimodipine in biological samples. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of high selective molecularly imprinted polymers for bisphenol A and 2,4-dichlorophenoxyacetic acid by using supercritical fluid technology

Molecularly imprinted polymers (MIPs) have been extensively used in chemical and biochemical related areas due to their high molecular recognition affinity and selectivity for the target molecule. On the other hand, supercritical polymerization is relatively novel technique, which can be applied in the polymerization without hazard organic solvent. This work introduces a supercritical fluid polymerization technique for preparation of MIP particles. The adsorption properties of prepared MIP particles are also investigated. The MIPs were prepared with methyl methacrylate (MMA) as a third monomer, methacrylic acid (MAA) as a functional monomer, templates (bisphenol A (BPA) and 2,4-dichlorophenoxyacetic acid (2,4-D)), methyl methacrylate (MMA) as a third vinyl monomer and ethylene glycol dimethacrylate (EGDMA) as a cross-linker. Equilibrium binding experiments are conducted to evaluate the binding characteristics of MIPs and templates (BPA and 2,4-D). The Scatchard plot analysis demonstrates that two classes of binding sites are formed with the equilibrium dissociation constants. The adsorption ability of the MIPs was also evaluated by measuring the adsorbed amounts of a similar imprinted template structure, the selectivity factor (α), and the imprinting-induced promotion of binding (IPB).     

Nanopore Molecularly Imprinted Polymer Membranes for Environmental Usage: Selective Separation of 2,4-Dichlorophenoxyacetic Acid as a Toxic Herbicide from Water

Nanopore molecularly imprinted polymers and membranes for selective separation of 2,4-dichlorophennoxyacetic acid were prepared using 2,4-dichlorophennoxyacetic acid as a template molecule, methacrylic acid as a functional monomer and trimethylolpropane trimethacrylate as a cross linker. Recognition properties of molecularly imprinted membranes were evaluated by performing binding experiments with analog phenoxyacetic acid. Flux, permeability, and permselectivity of the membranes as well as their properties were studied. Molecularly imprinted membrane-2 showed the equilibrium binding capacity of 34.57 mg/g and a selectivity factor of 12.96 toward 2,4-dichlorophennoxyacetic acid at 500 mg/l concentration. Permeability experiments indicated that molecularly imprinted membrane can recognize and absorb 2,4-dichlorophennoxyacetic acid from aqueous solutions’ selectively.     

一种可温度与pH调控的分子印迹光催化材料的制备及其性能

以氧氟沙星为模板分子,通过表面引发原子转移自由基聚合技术（SI-ATRP）,成功合成了一种智能凝胶接枝纳米TiO₂的分子印迹光催化材料（TiO₂-DR/MIPs）。采用透射电镜（TEM）、红外光谱（FTIR）、热重（TG）和X射线衍射（XRD）等方法对该材料进行了形貌及性质表征。分别研究了材料的温度与pH敏感性质及其对氧氟沙星光催化降解效率的影响,并对该材料的选择性和稳定性进行了探究。结果表明,TiO₂-DR/MIPs的粒径可随着温度与pH的变化呈现出良好的响应特性,并且可以通过改变环境温度和pH实现对其光催化活性的调控。TiO₂-DR/MIPs对氧氟沙星具有较好的选择性吸附和降解作用,且稳定性和重复使用效果好,经4次光催化降解循环实验后,光催化效率仅降低了5％。此外,TiO₂-DR/MIPs中的双敏感分子印迹层还可以有效地阻止纳米TiO₂的团聚,实现纳米TiO₂的均匀分散。     

Extraction and determination of malachite green from aquatic products based on molecularly imprinted polymers

Molecularly imprinted polymers (MIPs) were synthesized using malachite green (MG) as template, and methacrylic acid/sodium methacrylate as composite monomers. The equilibrium dissociation constant and apparent maximum adsorption capacity of the MIPs reach 12.2 mg·L^?1 and 3.2 mg·g^?1, respectively. The MIPs demonstrate excellent recognition ability due to high-affinity sites constructed by the electrostatic interaction and hydrogen bonds between template and composite monomers. The MIPs were successfully employed for the detection of MG residue in aquatic products coupled with high-performance liquid chromatography (HPLC) with a detection limit of 0.57 μg·kg^?1.     

Zn2+配位双模板印迹聚合物的制备表征及同时萃取升麻中的阿魏酸和咖啡酸

以Zn²⁺-阿魏酸-咖啡酸配合物为模板制备了双分子印迹聚合物,优化了制备条件,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,测试了分子印迹聚合物的吸附特性,探讨了分子印迹聚合物固相萃取应用效能并对萃取条件进行了优化.结果表明,当预反应混合液中金属离子、模板总量(阿魏酸-咖啡酸摩尔比为2:3)、功能单体及交联剂用量比为1:1:3:30(摩尔比)时,所得印迹聚合物对两种模板(阿魏酸和咖啡酸)均具有最好的吸附性能,吸附量分别达51.12mg/g和70.26mg/g.吸附动力学测试表明吸附3h,分子印迹聚合物可达到吸附平衡.用分子印迹聚合物进行固相萃取时,优化的淋洗过程为1.00mL H₂O、1.00mL甲醇-H₂O (3/7,体积比)及1.00mL甲醇-H₂O-ACN (4/4/2,体积比),洗脱溶剂为2.00mL甲醇.在优化条件下,分子印迹聚合物可同时选择富集升麻初提液中的阿魏酸和咖啡酸,二者回收率分别为92.67%和95.42%,而且产品中杂质少于用硅胶萃取所得产品.     

Optimal design of an imprinted preassembled system by quantum chemical calculations and preparation of a surface‐imprinted material for the selective removal of quinoline

In this study, we examined the rational preparation of molecularly imprinted polymers (MIPs) for the selective removal of quinoline from octane. Before the preparation, density functional theory, as one of the methods of quantum chemical calculation, was used for the simulation of a quinoline‐imprinted preassembly system. Methacrylic acid turned out to be the more suitable monomer for quinoline compared with acrylamide, and different template–monomer ratios, including 1:1, 1:2, and 1:3, were studied and are discussed. On the basis of the result of molecular simulation, quinoline‐imprinted polymers were prepared with a combination of surface imprinting and living polymerization. The prepared quinoline–MIPs were characterized and used as selective adsorbents for batch‐mode binding experiments. The fitting result of the adsorption data indicates that the adsorption kinetics and adsorption isotherms of the quinoline‐imprinted polymers fit well a pseudo‐second‐order kinetics model and the Freundlich model, respectively. A selective recognition ability was demonstrated by equilibrium binding analysis. This study will provide needful guidance and a theoretical basis for the preparation of imprinted materials in the field of industrial denitrification. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41730.     

Synthesis of the artemisinin‐imprinting polymers on silica surface and its adsorption behavior in supercritical CO2 fluid

Molecular imprinting polymers (MIPs) for artemisinin were prepared by using 3‐aminopropyltriethoxysilane and calix[4]arene bonded on silica particle surface as the functional monomers, tetraethoxysilicane as cross‐linker, and artemisinin as template. The MIPs were characterized by Fourier Transform Infrared Spectroscope and SEM. Their adsorption capacities were evaluated by static adsorption experiments. The MIPs showed high adsorption capacity and good selectivity for artemisinin. The maximum adsorption capacity of MIPs for artemisinin was 40.0 mg/g. The imprinting factor and the selective factor of the artemisinin‐imprinting polymers was 2.0 and 1.5, respectively. The imprinted film coating onto the silica surface showed a fast kinetics for recognizing and binding templates. Especially, mass transfer reaches the equilibrium within 3.5 h and the adsorption capacity of MIPs for artemisinin reached 120.0 mg/g in supercritical CO₂ fluid. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

Molecularly imprinted polymers for the selective recognition of l‐phenylalanine based on 1‐buty‐3‐methylimidazolium ionic liquid

To enhance the affinity of 4‐vinyl pyridine to l ‐phenylalanine (l ‐Phe) and convert the imprinting process from the aqueous phase to the organic phase, an oil‐soluble amino acid ionic liquid was introduced as a template. In this study, 1‐butyl‐3‐methylimidazolium α‐aminohydrocinnamic acid salt was first applied to prepared surface molecularly imprinted polymers (MIPs) in acetonitrile for the selective recognition of l ‐Phe. Fluorescence quenching analysis of the functional monomer on the template was investigated under different conditions to study the imprinting mechanism. Several binding studies, such as the sorption kinetics, sorption thermodynamics, and solid‐phase extraction application, and the chiral resolution of racemic phenylalanine were investigated. The binding isotherms were fitted by nonlinear regression to the Freundlich model to investigate the recognition mechanism. The affinity distribution analysis revealed that polymers imprinted by ionic liquid showed higher homogeneous binding sites than those imprinted by l ‐Phe. The competition tests were conducted by a molecularly imprinting solid‐phase extraction procedure to estimate the selective separation properties of the MIPs for l ‐Phe. The target MIP was shown to be successfully for the separation of l ‐Phe from an amino acid mixture. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42485.     

以混旋的头孢拉定为模板的分子印迹聚合物的制备及拆分性能研究

以混旋的头孢拉定为模板分子与合成的（S）-（1-苯乙基）-甲基丙烯酰胺作为功能单体制备分子印迹聚合物,并用高效液相色谱法对印迹聚合物的选择性进行了考察。实现了对混旋的头孢拉定的拆分。同样的方法分别制备了3种混旋的氨基酸衍生物的分子印迹聚合物,未能实现对其混旋物质的分离。对比得出结论：对混旋物质的直接印迹需要模板分子应具有4个以上的作用位点。