Preparation of molecularly imprinted polymers for recognition and extraction of benzoylureas from apple samples

ABSTRACT

In this work, diflubenzuron (DBZ) molecularly imprinted polymers (MIPs) were synthesized by precipitation polymerization. The polymers were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), dynamic light scattering (DLS). The influences of synthetic conditions including template molecules, functional monomers and crosslinker on the surface morphology, particle size and size distribution of polymers were investigated. Scatchard analysis indicated the presence of specified recognition sites in MIPs. The Sips model was fitted better to the equilibrium data of MIPs over whole concentrations. The pseudo-second-order kinetic model was well fitted to the experimental data of adsorption kinetic experiment, suggesting the chemisorption mechanism between MIPs and DBZ. Four structurally similar compounds were used for the selectivity test of MIPs. It was observed that MIPs can selectively rebind the template molecules (DBZ) under the interference of four other structurally similar compounds. The application of MIPs in solid-phase extraction (SPE) offers a method for extraction and determination of benzoylureas (BUs) pesticides in apple samples prior to high-performance liquid chromatography (HPLC) analysis.     

Equilibrium and kinetic isotherms and parameters for molecularly imprinted with sclareol poly(acrylonitrile‐co‐acrylic acid) matrix

The present work continues the previous studies concerning the synthesis and characterization of molecularly imprinted polymers (MIPs) with sclareol as template and three poly(acrylonitrile‐co‐acrylic acid) (AN:AA) copolymers with different ratios between monomers as matrices. The previous studies of rheology, elemental analysis, infrared spectroscopy, size exclusion chromatography, thermogravimetry, differential scanning calorimetry, batch rebinding tests, and Scatchard analysis, which confirmed the molecular imprinting, are being completed with the current equilibrium and kinetic adsorption studies. For this purpose, eight adsorption isotherms and three kinetic adsorption models were applied to six sets of experimental data obtained after three sclareol‐imprinted adsorbents (MIPs) and three nonimprinted adsorbents (NIPs) were submitted to batch adsorption experiments. After ordering the adsorption models according to the “minimum sum of normalized errors (SNE)” criteria, it was concluded that the adsorption in sclareol imprinted AN:AA copolymers is characterized by low surface coverage, takes place on heterogeneous binding sites and is reversible, while for NIPs the results suggest a difficult adsorption and/or easiness of template extraction, and that NIPs have homogeneous, but nonimprinted micropores. For the kinetic experiments, the minimum SNE for MIPs points to the first order kinetic model, fact that suggests a physical adsorption of template molecules on the imprinted sites. POLYM. ENG. SCI., 55:1152–1162, 2015. © 2014 Society of Plastics Engineers     

Surface molecularly imprinted polymer prepared by reverse atom transfer radical polymerization for selective adsorption indole

The preparation of indole molecularly imprinted polymers (indole‐MIPs) using 4‐vinylpyridine as functional monomer, silica gel as matrix were used to adsorb indole from fuel oil specifically. The reverse atom transfer radical polymerization (RATRP) technology was introduced to prepare the surface molecularly imprinted polymers, and the precipitation polymerization was adopted in the preparation process. The obtained indole‐MIPs were characterized by nitrogen adsorption, Fourier transform infrared spectrometry and scanning electron microscopy. The results show that indole‐MIPs were provided with the larger surface areas and more pores. The adsorption capacity of indole‐MIPs was 31.80 mg g^?1 at 298 K, and the adsorption equilibrium was reached in a short time. The adsorption process was spontaneous by thermodynamic analysis, and an appropriate decrease in temperature could enhance the adsorption capacity. The adsorption process obeyed pseudo‐second‐order kinetic model by kinetics analysis. The isotherm analysis results show that both Langmuir and Sips equations were suitable to experimental data. The selective adsorption and reusable performance of indole‐MIPs were favorable. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40473.     

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.     

Influence of synthesis conditions on the production of molecularly imprinted polymers for the selective recovery of isovaleric acid from anaerobic effluents

Two molecularly imprinted polymers (MIPs) – poly(methacrylic acid‐co‐TRIM) (TRIM, trimethylolpropanetrimethacrylate) and poly(acylamide‐co‐TRIM) – were synthesized in different solvents for the selective recovery of isovaleric acid (template) generated during the anaerobic digestion process. The chemical and structural characterizations of the synthetic adsorbent were carried out by Fourier transform infrared spectroscopy, TGA and porosimetry through N₂ adsorption–desorption isotherms. The selective and adsorptive performances of the imprinted polymers were evaluated by kinetic, isothermal, thermodynamic and selectivity studies and by adsorbent reuse experiments. The poly(methacrylic acid‐co‐TRIM) synthesized with dimethyl sulfoxide:chloroform presented higher selectivity and adsorption capacity for isovaleric acid in the presence of six volatile fatty acids. The kinetic results were well adjusted to the pseudo‐nth order and intraparticle diffusion models, leading to k values of 10^?4 and 6 × 10^?5 for the best synthesis of MIPs and not‐imprinted polymers, respectively. Moreover, the Sips model best described the adsorption isotherm and generated a maximum adsorption capacity of ca 209 mg g^?1 (at 25 °C). Cycles of MIP use–desorption–reuse indicated that the selective adsorbent performed better than commercial adsorbents, losing less than 3% of adsorption capacity after three cycles. © 2018 Society of Chemical Industry     

Comparison of molecular adsorption ability of the molecularly imprinted polymers prepared by ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate as cross linkers

The target of this study was to synthesize the molecularly imprinted polymers (MIPs) of L ‐phenylalanine as the solid phases for characterization of molecular adsorption by molecularly imprinted solid phase extraction (MISPE). These MIPs, in microscale, were synthesized using thermal (40°C)‐compared with thermal (65°C)‐initiated polymerization process. Itaconic acid was chosen as the functional monomers, and either ethylene glycol dimethacrylate or trimethylolpropane trimethacrylate (TRIM) was used as the cross linker and was compared together. The influences of several parameters on the properties of the MIPs were investigated, especially physical robustness from the percentage yields and molecular adsorption from the percentage recovery by MISPE. The best yields were obtained from polymers made using TRIM and thermal (65°C)‐initiated polymerization. However, there were no significant differences in molecular adsorption. It was concluded that these parameters can be considered to synthesize MIPs for chiral separation in advance steps such as other related chromatographic techniques. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2325–2330, 2007     

戊唑醇-三唑酮双模板分子印迹聚合物在烟叶农残检测中的应用

以戊唑醇（TBZ）和三唑酮（TDF）为双模板分子,甲基丙烯酸（MAA）为功能单体,乙二醇二甲基丙烯酸酯（EGDMA）为交联剂,按摩尔比为1∶4∶20制备了戊唑醇-三唑酮双模板分子印迹聚合物（MIPs）。考察了MIPs的吸附动力学、静态吸附及亲和位点特征和选择识别性能。结果表明,MIPs可在2.5h内达到吸附平衡,Scatchard分析得出MIPs存在高低两类亲和位点,且具有良好的组选择性和特异选择性。以MIPs作为固相萃取填料,制备分子印迹固相萃取柱（MISPE）用于烟叶样品前处理,并建立MISPE-超高效液相色谱-串联质谱法检测烟叶中（戊唑醇、三唑酮、腈菌唑和三唑醇）残留的方法。结果显示,MISPE柱对戊唑醇、三唑酮、腈菌唑和三唑醇的富集效果较好,平均回收率为72%～110.3%,相对标准偏差在2.38%～7.92%(n=3)。该方法简单、选择性高,可实现对烟叶中三唑类杀菌剂残留的准确分析。     

Solid-phase extraction of S-(-)-amlodipine from plasma with a uniformly sized molecularly imprinted polymer

To specifically extract S-(-)-amlodipine from plasma, uniformly sized molecularly imprinted polymers (MIPs) for S-(-)-amlodipine were prepared in an aqueous system by multistep swelling and polymerization with methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a crosslinker, and toluene as a porogen. Scanning electron microscopy was used to identify the structural features of the obtained polymers. ¹H-NMR and high-performance liquid chromatographic analysis were performed to explore the possible recognition mechanism. The results reveal that spherical polymer beads with uniform size and good monodispersity were obtained, and the MIPs showed specific recognition ability for the template molecule. The ionic hydrophobic and hydrogen-bonding interactions were inferred to play an important role in the recognition mechanism. The results indicate that the MIPs could be used as a solid-phase extraction sorbent for the concentration and purification of S-(-)-amlodipine from plasma with a high efficiency. The linear range was 0.25–8.00 μg/mL with a correlation coefficient of 0.9948. The average recovery was 98.3% with relative standard deviation (RSD) less than 9.1%. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Simple preparation and characterization of molecularly imprinted nylon 6 nanofibers for the extraction of bisphenol A from wastewater

Nylon 6 nanofibers incorporated with molecularly imprinted polymers (MIPs) were successfully fabricated by electrospinning with fiber diameters in the range 80–145 nm. Then, they were used as a new material for the extraction of selected bisphenol A (BPA) in water samples. Field emission scanning electron microscopy images revealed that the nanofibers had a smooth morphology with a good incorporation of MIPs. The Fourier transform infrared and energy-dispersive X-ray spectroscopy results also confirmed the formation of the MIPs in the nanofibers. Furthermore, Raman spectroscopy showed that the crystalline structure of the pristine nylon 6 nanofiber was a kind of α form, and the incorporation of MIPs led to a γ-form structure in the nanofibers; this proved the interactions between nylon 6 and the MIPs. Adsorption studies also confirmed that the adsorption efficiency of BPA onto the molecularly imprinted polymer nanofibers (MIP-NFs; 83.5%) was much greater than that onto nonimprinted polymer nanofibers (NIP-NFs; 36.8%). Also, the imprinting factor was 3.4; this strongly implied the successful formation of molecularly imprinted cavities on the MIP-NFs with a strong affinity to BPA. The maximum adsorption capacity of the MIP-NFs was 103.8 mg/g. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47112.     

Mixed templates molecularly imprinted solid‐phase extraction for the detection of sulfonamides in fish farming water

Highly selective molecularly imprinted polymers (MIPs) that absorb sulfonamides (SAs) are prepared using two types of SAs as mixed templates, 2‐vinylpyridine as the functional monomer and ethylene glycol dimethacrylate as the crosslinker. The optimum combination of the mixed templates, their adsorption effect and the imprinting mechanism are evaluated based on SPE recoveries of a family of analytes, equilibrium binding, BET surface area analysis and UV. The results indicate that the mixed templates not only optimize the cavities of the MIPs but also improve the MIPs selectivity and adsorption capacity for the target analytes in aqueous solution. Therefore, MIPs are used for the quantitative analysis of SAs in fish farming water using off‐line SPE coupled to HPLC/DAD. The recovery and RSD were 84.16–101.19 and 1.98–7.10%, respectively. Four SAs analytes were detected in four types of water samples in the range of 8.49–74.60 ng L^?1. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41491.     

智能印迹聚合物及其外场强化的识别机制研究进展

智能印迹聚合物在外部环境刺激下对模板分子具有响应性分子识别吸附能力,在吸附分离、药物传递、检测、固相萃取、催化等应用领域有着广阔的前景。本文首先对分子印迹聚合物进行了综述并指出在外场强化过程中常规分子印迹聚合物很难通过改变结合位点来控制结合特性的问题,针对这个问题进而提出具有柔性位点的智能响应型印迹聚合物。随后以具有不同响应功能的智能印迹聚合物为出发点,对磁、热、光、pH、生物大分子等单因子及双重因子响应功能印迹聚合物在外场强化过程中的响应与识别机制分别进行分析与总结,并综述了近些年来这些智能印迹聚合物在不同应用领域中相关研究工作进展。最后,基于不同响应功能的智能印迹聚合物的现状问题,对智能印迹聚合物在材料制备与理论两方面分别进行了展望。     

One‐pot method for obtaining hydrophilic tetracycline‐imprinted particles via precipitation polymerization in ethanol

In this study, we used a green, one‐pot method to synthesize hydrophilic molecularly imprinted polymers (MIPs) via the precipitation polymerization of hydrophilic monomers in ethanol. The as‐prepared materials were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, dynamic light scattering, and water contact angle measurements (27.3 ± 0.1°). As compared to the imprinting and nonimprinting processes, tetracycline (TC), as a template molecule, had an important effect on the morphology of the MIPs, and the possible mechanism is discussed in detail. We also discuss the effects of the parameters on the binding performance as determined by batch adsorption experiments in pure water. The adsorption capacity increased with increasing concentration and temperature at an optimum pH of 5.0. The Langmuir isotherm fitted the data better, with a maximal concentration of 45.75 μmol/g at 318 K. The kinetic properties of the MIPs (within 3.0 h) toward TC were analyzed with pseudo‐first‐order and pseudo‐second‐order kinetic equations and the intraparticle diffusion model. The MIPs exhibited specific recognition toward TC, and other competitive antibiotics were used as references. All of the results indicate that the MIPs exhibited a large adsorption capacity and great specific recognition for TC. The high affinity to TC of the MIPs, with its fast and easy fabrication, provides them with potential applications in the selective separation of the TC antibiotics from an aqueous environment. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40071.     

Grafting of molecularly imprinted polymers from the surface of Fe3O4 nanoparticles containing double bond via suspension polymerization in aqueous environment: A selective sorbent for theophylline

Molecularly imprinted polymers (MIPs) were grafted from the surface of Fe₃O₄ nanoparticles containing double bond via suspension polymerization in aqueous environment, and the leakage of Fe₃O₄ nanoparticles from MIPs was overcome in this study. The effect of different cross‐linker on adsorption capacity of the resultant magnetic MIPs was investigated using pure trimethylolpropane trimethacrylate (TRIM) or the mixture of TRIM and divinylbenzene (DVB) as cross‐linker. Both magnetic MIPs exhibited higher adsorption capacity for the template theophylline than the corresponding non‐imprinted polymer, and Freundlich model fitted reasonably well for theophylline adsorption on both magnetic MIPs. In addition, both magnetic MIPs exhibited good recognition properties for the template theophylline versus caffeine, and the selectivity of magnetic MIPs using pure TRIM as cross‐linker (mag‐MIP‐TRIM) was much higher than those using the mixture of TRIM and DVB as cross‐linker (mag‐MIP‐TRIM and DVB). The adsorption dynamics of theophylline on both magnetic MIPs fitted well with the first‐order kinetic model, but the adsorption equilibrium on mag‐MIP‐TRIM and DVB reached faster than that on mag‐MIP‐TRIM. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Adsorption and selective recognition of 17?-estradiol by molecularly imprinted polymers

The 17?-estradiol-imprinted polymers using non-covalent approach with methacrylic acid as the functional monomer was prepared and characterized. The effect of porogenic solvents on the adsorption capacity and thermal stability of the molecularly imprinted polymers (MIPs) were examined. Scanning electron microscopic images showed that the synthesized MIPs were bulk porous materials. The surface areas of MIPs increased from 151?C188 to 239?C292?m²?g^-1 when templates were removed by methanol using Soxhlet extraction. In addition, the MIPs prepared in chloroform had a higher adsorption capacity towards 17?-estradiol (1,212???g?g^-1) than that in acetonitrile (769???g?g^-1), indicating that less polar porogenic solvent is suitable for synthesis of non-covalent MIPs. FTIR showed that the carbonyl group is the major functional group in MIPs to form monomer-template complex via H-bond. In addition, only a slight decrease (< 5?%) in adsorption capacity of the MIPs was observed when incubated at 80?°C for 5?h. Analysis of the capacity factor values (??_imp??) for MIPs indicated that the rebinding ability from selective recognition sites of MIPs decreased in the order 17?-estradiol?>?testosterone?>?benzo[a]pyrene?>?progesterone?>?phenol, and the ??_imp?? values decreased from 2.68 to 0.63, indicating the excellent selectivity of MIPs among closely related compounds. Results obtained in this study clearly indicate that the imprinted polymer is specific for recognizing 17?-estradiol. The excellent selectivity and high adsorption capacity of 17?-estradiol-imprinted polymers open the door to develop MIPs for effective separation and adsorption of estrogenic compounds.     

三硝基甲苯分子印迹电化学传感器的制备和应用

以三硝基甲苯（TNT）为模板分子,甲基丙烯酸（MAA）为功能单体,采用乳液聚合法制备TNT的分子印迹聚合物（MIPs）。将制备的MIPs分散在溶剂中,通过表面涂覆法制备出检测TNT的分子印迹电化学传感器。紫外光谱表明TNT与MAA之间存在相互作用力,有助于形成结构稳定、亲和性强的MIPs。利用扫描电镜观测不同制备条件下印迹聚合物的表观形貌,发现溶剂用量为30mL、乳化剂用量为12mg时制备的聚合物形貌较优异。吸附实验表明MIPs对TNT的吸附量随着TNT初始浓度的增加而增加,140min后达到最大吸附量的95%。MIPs对TNT的分离常数远大于RDX和DNT,对RDX和DNT的选择性系数均达到4.4以上,说明MIPs对TNT有较好的选择性吸附能力。铁氰化钾探针实验和对TNT的响应曲线验证了电化学传感器的成功制备,该传感器富集3min就达到了最大电流值的94%,5min内达到吸附平衡。TNT浓度在0.1~5mg/mL的范围内与峰电流有良好的线性关系,检出限为0.06mg/mL。MIPs传感器对TNT的电流响应分别为DNT和RDX的3.13倍、3.27倍,说明其对TNT分子具有很强的特异性识别能力。     

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     

有机-无机分子印迹杂化材料的研究进展

分子印迹技术是制备选择性识别特定分子的聚合物的方法,因其制备简单、稳定性好且具有特异分子识别功能使其在色谱分离、固相萃取、化学传感和模拟酶催化等方面都有广泛的应用。有机-无机杂化分子印迹聚合物集有机和无机聚合物的优点,不仅机械强度高,而且耐溶剂性好,是分子印迹技术的一个崭新领域。在介绍有机-无机杂化分子印迹聚合物基本概况的基础上,综述了有机-无机杂化分子印迹聚合物制备的原理、方法和特点,并对未来的发展提出了展望。     

硫丹分子印迹聚合物的合成及吸附特性分析

采用分子印迹技术,以α-甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,偶氮二异丁腈为引发剂,乙腈为致孔剂,合成以硫丹为模板的印迹聚合物微球。首先利用紫外光谱方法研究了模板与功能单体相互作用情况,采用平衡吸附试验对印迹聚合物吸附效率进行了表征,与化学组成相同的空白聚合物相比,印迹聚合物微球对模板分子具有更高的吸附效率,按最佳合成条件得到的印迹聚合物最大表观吸附量达42.56 mmol/g。     

Surface molecularly imprinted polymer microspheres based on nano‐TiO2 for selective recognition of kaempferol

The molecular imprinting technique is a new method for preparing molecularly imprinted polymers (MIPs) with specific molecular recognition sites for certain target molecules. In this study, a novel, facile preparation method was presented, called “seed precipitation polymerization,” for the synthesis of MIPs via surface imprinting and a support matrix. In the polymerization process, kaempferol was used as the template molecule, methacrylic acid as the functional monomer, nano‐TiO₂ as the support, azodiisobutyronitrile as the initiator, and ethylene glycol dimethacrylate as the crosslinker in acetonitrile solvent. The synthesized T‐MIP and MIP were analyzed by infrared spectroscopy and scanning electron microscopy. In addition, the obtained polymers were evaluated by adsorption isotherms and dynamic curves for their selective recognition properties for kaempferol. The results show that T‐MIP shows regular spherical particles; the adsorption dynamic curves of T‐MIP show that the adsorption capacity increases with time and reaches a maximum value and then finally reaches equilibrium, and the T‐MIP exhibits a higher affinity for kaempferol than does the MIP. The adsorption follows pseudo‐second‐order kinetics, the Freundlich adsorption equation fits the experimental data well, and there is strong evidence for multiple‐layer adsorption. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44888.     

Molecular imprinted solid‐phase extraction of huperzine A from Huperzia Serrata

On the basis of the non‐covalent interaction between template and monomer, porous molecularly imprinted polymers (MIPs) were synthesized by a thermal‐initiated polymerization method using huperzine A as template, acrylamide, or methacrylic acid as function monomer, ethylene glycol dimethacrylate as cross‐linking agent. The interaction between template and functional monomers was studied by UV spectrophotometry, which showed a formation of huperzine A‐monomer complexes with stoichiometric ratio of 1 : 2 in the pre‐polymerized systems. The resultant MIP particles were tested in the equilibrium binding experiment to analyze their adsorption ability to huperzine A, and were characterized by Fourier Transform Infrared (FTIR) study. The recognition properties of MIP were estimated in solid‐phase extraction by selecting four compounds (isolated from the Chinese herb Huperzia serrata) as substrates, and were compared with and prior to those of the NIP. High affinity and adsorption of MIP1 which was prepared in chloroform with huperzine A as imprinted molecule, and acrylamide (AM) as functional monomer, made an attractive application of MIP1 in separation processes. In final, using MIP1 solid‐phase extraction micro‐column, huperzine A was enriched and separated from the real extraction sample of Huperzia serrata. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009