Preparation of sterol-imprinted polymers with the use of 2-(methacryloyloxy)ethyl phosphate.

Steroid-selective polymers were prepared by the molecular imprinting technique, using 2-(methacryloyloxy)ethyl phosphate as functional monomer. The retentivity and selectivity of the obtained imprinted polymers were evaluated by liquid chromatography. The cholesterol-imprinted polymer showed higher affinity for cholesterol than that for cholesterol derivatives. The selectivity of the imprinted polymer was superior to the imprinted polymer prepared with the conventional functional monomer, 2-(trifluoromethyl)acrylic acid. Estradiol was also imprinted and gave similar results, demonstrating that 2-(methacryloyloxy)ethyl phosphate would be suitable for imprinted polymers of cholesterol and related compounds.     

新型功能单体分子印迹聚合物的研究进展

分子印迹聚合物是近年发展起来的新型重要分子识别材料,功能单体是其识别性能最重要的影响因素之一,因此,对新型功能单体分子印迹聚合物的研究越来越受重视.基于分子印迹聚合物在固相萃取、色谱柱分离、传感器等方面的应用,对新型功能单体分子印迹聚合物的研究进展进行了综述.     

Isolation of sinapic acid from broccoli using molecularly imprinted polymers

A molecularly imprinted polymer was synthesized for the purpose of sinapic acid isolation from Egyptian nutraceutical Botrytis italica, L. (broccoli) due to its prominent medicinal and wide pharmacological activities. A computational study was first developed to determine the optimal template to functional monomer molar ratio. Based on the computational results, five polymers were synthesized using a bulk polymerization method with sinapic acid as the template molecule. Evaluation of the synthesized polymers binding performance was carried out using batch rebinding assay, which revealed that the molecularly imprinted polymer of molar ratio (1:4:20), template to functional monomer (4‐vinyl pyridine) to crosslinker (ethylene glycol dimethacrylate) was of optimum performance, thus, this polymer was applied for sinapic acid isolation from closely related analogues. This represents a more practical approach to isolate sinapic acid from different natural extracts selectively.     

An Artificial Estrogen Receptor through Combinatorial Imprinting

Polymeric sorbents targeting endocrine‐disrupting estrogen active compounds (EAC) were prepared by terpolymer imprinting using 17β‐estradiol (E2) as template. From a group of eight functional monomers representing Brønsted acids, bases, hydrogen‐bond donors and acceptors, as well as π‐interacting monomers, a terpolymer library that comprises all possible binary combinations of the functional monomers was prepared. Binding tests revealed that imprinted polymers exhibit a markedly higher affinity for E2 compared to nonimprinted polymers (NIPs) or polymers prepared by using single functional monomers. A combination of methacrylic acid (MAA) and p‐vinylbenzoic acid offered a particularly promising lead polymer, displaying an imprinting factor of 17 versus 2.4 for a benchmark polymer prepared by using only MAA as functional monomer. The saturation capacities ascribed to imprinted sites were four to five times higher for this polymer compared to previously reported imprinted polymers. NMR titrations and molecular dynamics simulations corroborated these results, indicating an orthogonal preference of the two functional monomers with respect to the E2 3‐OH and 17‐OH groups. The optimized polymer exhibited a retentivity for EACs that correlates with their inhibitory effect on the natural receptor. By using the optimized molecularly imprinted polymers (MIPs) in a model water‐purification system, they were capable of completely removing ppb levels of a small group of EACs from water. This is in contrast to the performance of nonimprinted polymers and well‐established sorbents for water purification (e.g., active carbon), which still contained detectable amounts of the compounds after treatment.     

Theoretical and experimental research on the self‐assembled system of molecularly imprinted polymers formed by salbutamol and methacrylic acid

The quantum chemical method was applied for screening functional monomers in the rational design of salbutamol‐imprinted polymers. Salbutamol was the template molecule, and methacrylic acid was the single functional monomer. The LC‐WPBE/6–31G(d,p) method was used to investigate the geometry optimization, active sites, natural bond orbital charges, binding energies of the imprinted molecule, and solvation energy. The mechanism of action between salbutamol and methacrylic acid was also discussed. The theoretical results show that salbutamol interacts with functional monomers by hydrogen bonds, and the salbutamol‐imprinted polymers with a ratio of 1:4 (salbutamol/methacrylic acid) in acetonitrile had the highest stability. The salbutamol‐imprinted polymers were prepared by precipitation polymerization. The experimental results indicated that the maximum adsorption capacity for salbutamol toward molecularly imprinted polymers was 7.33 mg/g, and the molecularly imprinted polymers had a higher selectivity for salbutamol than for norepinephrine and terbutaline sulfate. Herein, the studies can provide theoretical and experimental references for the salbutamol molecular imprinted system.     

沉淀聚合制备诺氟沙星-Zn2+分子印迹聚合物及其印迹方式的研究

采用沉淀聚合的方式以诺氟沙星(NFA)-Zn2+为模板分子,乙二醇二甲基丙烯酸酯为交联剂,分别选取酸性功能单体甲基丙烯酸与碱性功能单体4-乙烯基吡啶制备了诺氟沙星-Zn2+的分子印迹聚合物.通过紫外光谱研究发现诺氟沙星与Zn2+及两种功能单体均发生了金属配位印迹作用且形成了比例不同的印迹复合物.红外光谱的功能基团的表征结果显示,甲基丙烯酸与诺氟沙星-Zn2+形成了以诱导作用占优的三元配合物,而4-乙烯基吡啶则与诺氟沙星-Zn2+形成了共轭作用占优的三元配合物.扫描电镜及粒径分布实验表征了聚合物的物理特性,结果显示印迹聚合物的表面存在孔及孔道结构而非印迹聚合物的表面较致密不存在孔且制备的印迹聚合物的粒径均在100μm以下,其平均粒径为39μm.等温结合及选择性实验的结果表明4-乙烯基吡啶为功能单体制备的印迹聚合物的选择性识别性能优于甲基丙烯酸为功能单体制备的印迹聚合物,其特异性吸附容量和印迹指数分别为66.84μmol/g和4.207.同时在混合溶液的选择性实验中以4-乙烯基吡啶(4-VP)为功能单体制备的印迹聚合物的选择识别诺氟沙星的能力优于以甲基丙烯酸为功能单体的聚合物,其识别因子分别为3.408和2.909,而非印迹聚合物对底物的吸附量较小且识别因子均接近于1,说明非印迹聚合物对底物的识别为非选择性的.     

Chromatographic characteristics of cholesterol-imprinted polymers prepared by covalent and non-covalent imprinting methods

Cholesterol-imprinted polymers were prepared in bulk polymerization by the methods of covalent and non-covalent imprinting. The former involved the use of a template-containing monomer, cholesteryl (4-vinyl)phenyl carbonate, while the latter used the complexes of template and functional monomer, methacrylic acid or 4-vinylpyridine prior to polymerization. Columns packed with these molecularly imprinted polymers (MIPs) were all able to separate cholesterol from other steroids. For different combinations of cholesterol and beta-estradiol concentrations in a total of 1 g/l, the peak retention times for both compounds were nearly constant. The adsorption capacity for cholesterol onto the MIPs was found to significantly depend on the use of functional monomers, but the selectivity factors were only slightly different from each other at 2.9 to 3.2 since the separation was all based on the specific binding of cholesterol to recognition sites formed on the imprinted polymers. The capacity factors for cholesterol were determined to be 3.5, 4.0 and 3.1, respectively, for covalently imprinted, 4-vinylpyridine-based, and methacrylic acid-based non-covalently imprinted polymers. However, the covalently imprinted polymer was found to have a higher adsorption capacity for cholesterol and about fivefold higher chromatographic efficiency for cholesterol separation, in comparison with non-covalently imprinted polymers. The use of covalent imprinting significantly reduced the peak broadening and tailing. This advantage along with constant retention suggests that the covalently imprinted polymer has potential for quantitative analysis.     

L-酪氨酸印迹分子的制备及性能研究

利用分子印迹技术采用传统加热法制备出酪氨酸他子印迹聚合物。用红外光谱分析了聚合物结构。研究了印迹他子与功能单体的物质的量对聚合物结合性的影响,吸收效率表征结果显示,与化学组成相同的空白聚合物相比,印迹聚合物具有更高的吸附效率。     

Design of EGDMA‐Crosslinked Theophylline Imprinted Polymer with High Specificity and Selectivity

An attempt has been made to design theophylline selective polymers with maximum selectivity and specificity, and to relate the rebinding capacity of the polymers with the degree of crosslinking, as well as with the template‐monomer ratio. The theophylline imprinted and non‐imprinted polymers based on methacrylic acid as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as crosslinking agent (35–80 mol%) were prepared. The developed imprinted polymers were characterized by FT‐IR, ¹H and ¹³C‐NMR spectra. Equilibrium binding of theophylline by the imprinted and non‐imprinted polymers were investigated and optimized the conditions. Imprinted polymers showed specific binding of the template theophylline. Selectivity of the imprinted polymers was investigated towards caffeine and nicotine. Imprinted polymers showed specific and selective binding of theophylline, which varied with the degree of EGDMA crosslinking. Equilibrium rebinding experiments proved that imprinted polymer with moderate (70%) crosslinking with 1∶2 template‐functional monomer ratio is ideal with maximum specificity and selectivity.     

分子烙印聚合物作为高效毛细管电泳添加剂的研究

分子洛印聚合物（molecular imprinted polymer)是一种高选择的有分子记忆效应的主体分子,通常在非极性环境中制备和应用。该文在极性溶剂中利用离子化作用和疏水作用制备了非共价的分子烙印聚合物,并将其作为高效毛细管电泳流动相添加剂;在含水缓冲溶液条件下,研究了单体种类、分子烙印聚合物颗粒度和含量、缓冲溶液pH值以及分离电压对分子烙印聚合物识别模板分子的影响。结果证明了在质子溶剂中制备和应用非共价分子烙印聚合物是可行的。     

Enantiomeric Resolution on L—Carnitine Selective Polymers Prepared by Molecular Imprinting

L-carnitine selective polymers were prepared by molecular imprinting using methacrylic acid as the functional monomer. The acid function of the monomer is expected to form hydrogen bond and ionic interactions with the amine function of the target molecule L-carnitine.The imprinted polymers were used as stationary phases in high-performance liquid chromatography (HPLC). It was shown that L-carnitine imprinted polymer exhibited a higher affinity to its template molecule,while the non-imprinted polymer had no affinity to the compounds tested. Racemic carnitine hydrochloride was efficiently resolved on the L-carnitine imprinted polymer, and the separation factor is 1.9.     

Preparation of novel curcumin‐imprinted polymers based on magnetic multi‐walled carbon nanotubes for the rapid extraction of curcumin from ginger powder and kiwi fruit root

A novel molecularly imprinted polymer based on magnetic phenyl‐modified multi‐walled carbon nanotubes was synthesized using curcumin as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross‐linker. The phenyl groups contained in the magnetic imprinted polymers acted as the assisting functional monomer. The magnetic imprinted polymers were characterized by scanning electron microscopy, Fourier‐transform infrared spectroscopy and vibrating sample magnetometry. Adsorption studies demonstrated that the magnetic imprinted polymers possessed excellent selectivity toward curcumin with a maximum capacity of 16.80 mg/g. Combining magnetic extraction and high‐performance liquid chromatography technology, the magnetic imprinted polymer based on magnetic phenyl‐modified multi‐walled carbon nanotubes was applied for the rapid separation and enrichment of curcumin from ginger powder and kiwi fruit root successfully.     

Ternary choline chloride/caffeic acid/ethylene glycol deep eutectic solvent as both a monomer and template in a molecularly imprinted polymer

A molecularly imprinted polymer based on a ternary deep eutectic solvent comprised of choline chloride/caffeic acid/ethylene glycol was prepared. The caffeic acid in the ternary deep eutectic solvent was used as both a monomer and template. The molecularly imprinted polymer based on the ternary deep eutectic solvent was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, field‐emission scanning electron microscopy, Brunauer–Emmett–Teller surface area analysis, atomic force microscopy, and elemental analysis. A series of molecularly imprinted polymers based on choline chloride/caffeic acid/ethylene glycol with different molar ratios was prepared and applied to the molecular recognition of polyphenols. A comparison of the recognition ability of molecularly imprinted polymers to polyphenols revealed that the choline chloride/caffeic acid/ethylene glycol (1:0.4:1, molar ratio) molecularly imprinted polymer had the best molecular recognition effect with 132 μg/g of protocatechuic acid, 104 μg/g of catechins, 80 μg/g of epicatechin, and 123 μg/g of caffeic acid in 6 h, as well as good molecular recognition ability for polyphenols from a Radix Asteris sample. These results show that the ternary deep eutectic solvent based molecularly imprinted polymer is a potential medium that can be applied to drug purification, drug delivery, and drug analysis.     

Preparation and application of molecularly imprinted polymer for isolation of chicoric acid from Chicorium intybus L. medicinal plant

Molecularly imprinted polymer (MIP) was synthesized and applied for the extraction of chicoric acid from Chicory herb (Chicorium intybus L.). A computational study was developed to find a suitable template to functional monomer molar ratio for MIP preparations. The molar ratio was chosen based on the comparison of the binding energy of the complexes between the template and functional monomers. Based on the computational results, eight different polymers were prepared using chicoric acid as the template. The MIPs were synthesized in a non-covalent approach via thermal free-radical polymerization, using two different polymerization methods, bulk and suspension. Batch rebinding experiments were performed to evaluate the binding properties of the imprinted polymers. The best results were obtained with a MIP prepared using bulk polymerization with 4-vinylpyridine (4-VP) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the crosslinker with a molar ratio of 1:4:20. The best MIP showed selective binding ability toward chicoric acid in the presence of the template’s structural analogues, caffeic acid, caftaric acid and chlorogenic acid.     

Water‐compatible molecularly imprinted polymer as a sorbent for the selective extraction and purification of adefovir from human serum and urine

A molecularly imprinted polymer has been synthesized to specifically extract adefovir, an antiviral drug, from serum and urine by dispersive solid‐phase extraction before high‐performance liquid chromatography with UV analysis. The imprinted polymers were prepared by bulk polymerization by a noncovalent imprinting method that involved the use of adefovir (template molecule) and functional monomer (methacrylic acid) complex prior to polymerization, ethylene glycol dimethacrylate as cross‐linker, and chloroform as porogen. Molecular recognition properties, binding capacity, and selectivity of the molecularly imprinted polymers were evaluated and the results show that the obtained polymers have high specific retention and enrichment for adefovir in aqueous medium. The new imprinted polymer was utilized as a molecular sorbent for the separation of adefovir from human serum and urine. The serum and urine extraction of adefovir by the molecularly imprinted polymer followed by high‐performance liquid chromatography showed a linear calibration curve in the range of 20–100 μg/L with excellent precisions (2.5 and 2.8% for 50 μg/L), respectively. The limit of detection and limit of quantization were determined in serum (7.62 and 15.1 μg/L), and urine (5.45 and 16 μg/L). The recoveries for serum and urine samples were found to be 88.2–93.5 and 84.3–90.2%, respectively.     

Preparation of molecularly imprinted polymers for strychnine by precipitation polymerization and multistep swelling and polymerization and their application for the selective extraction of strychnine from nux‐vomica extract powder

Monodisperse molecularly imprinted polymers for strychnine were prepared by precipitation polymerization and multistep swelling and polymerization, respectively. In precipitation polymerization, methacrylic acid and divinylbenzene were used as a functional monomer and crosslinker, respectively, while in multistep swelling and polymerization, methacrylic acid and ethylene glycol dimethacrylate were used as a functional monomer and crosslinker, respectively. The retention and molecular recognition properties of the molecularly imprinted polymers prepared by both methods for strychnine were evaluated using a mixture of sodium phosphate buffer and acetonitrile as a mobile phase by liquid chromatography. In addition to shape recognition, ionic and hydrophobic interactions could affect the retention of strychnine in low acetonitrile content. Furthermore, molecularly imprinted polymers prepared by both methods could selectively recognize strychnine among solutes tested. The retention factors and imprinting factors of strychnine on the molecularly imprinted polymer prepared by precipitation polymerization were 220 and 58, respectively, using 20 mM sodium phosphate buffer (pH 6.0)/acetonitrile (50:50, v/v) as a mobile phase, and those on the molecularly imprinted polymer prepared by multistep swelling and polymerization were 73 and 4.5. These results indicate that precipitation polymerization is suitable for the preparation of a molecularly imprinted polymer for strychnine. Furthermore, the molecularly imprinted polymer could be successfully applied for selective extraction of strychnine in nux‐vomica extract powder.     

麻黄碱印迹聚合物合成条件对其形态及结合特性的影响

印迹聚合物合成条件对聚合物性能的影响是分子印迹技术中的一项重要研究内容。以左旋麻黄碱为印迹分子,甲基丙烯酸为功能单体,使用不同的交联剂和致孔剂合成了印迹聚合物,并对所得到的印迹聚合物的比表面积、孔结构和结合特性进行了评价。研究结果说明合成的印迹聚合物对印迹分子具有很好的亲和能力及选择性。致孔剂可以影响聚合物比表面积的大小及单体组成。氯仿是甲基丙烯酸-乙二醇二甲基丙烯酸酯和甲基丙烯酸-季戊四醇三丙烯酸酯聚合链的良溶剂,导致了比表面积及孔容较小的聚合物结构;而以乙腈为致孔剂得到的聚合物有较大的比表面积。共聚物中羧基含量的测定结果也说明,在预聚溶液中单体浓度相同的条件下,以不同的致孔剂进行合成得到的聚合物中甲基丙烯酸的比例不同。聚合物的比表面积及单体浓度的差别都可能导致聚合物的结合容量不同。     

Computer‐aided design and synthesis of magnetic molecularly imprinted polymers with high selectivity for the removal of phenol from water

A molecular simulation method was introduced to compute the phenol–monomer pre‐assembled system of a molecularly imprinted polymer. The interaction type and intensity between phenol and monomer were evaluated by combining binding energy and charge transfer with complex conformation. The simulation results indicate that interaction energies are simultaneously affected by the type of monomer and the ratio between phenol and monomers. At the same time, we considered that by increasing the amount of functional monomer is not always better for preparing molecularly imprinter polymers. In this study, three kinds of novel magnetic phenol‐imprinted polymers with favorable specific adsorption effects were prepared by the surface imprinting technique combined with atom transfer radical polymerization. Various measures were selected to characterize the structure and morphology to obtain the optimal polymer. The characterization results show that the optimal polymer has suitable features for further adsorption process. A series of static adsorption experiments were conducted to analyze its adsorption performance, which follows the Elovich model from the kinetic analysis and the Sips equation from the isothermal analysis. To further verify the reliability and accuracy of the simulation results, the effects of different monomers on the adsorption selectivity were also determined. They display higher selectivity towards phenol than 4‐nitrophenol.The results from the simulation of the pre‐assembled complexes are in reasonable agreement with those from the experiment.     

Cost‐effective imprinting combining macromolecular crowding and a dummy template for the fast purification of punicalagin from pomegranate husk extract

The combination of molecular crowding and virtual imprinting was employed to develop a cost‐effective method to prepare molecularly imprinted polymers. By using linear polymer polystyrene as a macromolecular crowding agent, an imprinted polymer recognizable to punicalagin had been successfully synthesized with punicalin as the dummy template. The resulting punicalin‐imprinted polymer presented a remarkable selectivity to punicalagin with an imprinting factor of 3.17 even at extremely low consumption of the template (template/monomer ratio of 1:782). In contrast, the imprinted polymer synthesized without crowding agent, did not show any imprinting effect at so low template amount. The imprinted polymers made by combination of molecular crowding and virtual imprinting can be utilized for the fast separation of punicalagin from pomegranate husk extract after optimizing the protocol of solid‐phase extraction with the recovery of 85.3 ± 1.2%.     

Miniaturized molecularly imprinted polymer extraction method for the gas chromatographic analysis of flavonoids

In this study, the use of monolithic molecularly imprinted polymers in a micropipette tip format allowing the simple and fast extraction of flavonoids from standard solutions and a black tea sample is demonstrated. The imprinted polymer employed quercetin, methacrylic acid or 4‐vinylpyridine, and ethylene glycol dimethacrylate as template, functional monomer, and cross‐linker, respectively. Surface morphologies of the quercetin‐imprinted polymers and the corresponding nonimprinted polymers were characterized by SEM. Extraction of flavonoid standards was performed to evaluate the selectivity and recovery with these imprinted and nonimprinted polymers. Flavonoid compositions in aliquots eluted from the tips were identified using fast GC with flame ionization detection. Maximum specific capacities of 0.2, 5.7, and 16.0 mg/g for catechin, morin, and quercetin, respectively, were obtained with the imprinted polymer prepared with methacrylic acid, with the corresponding recoveries of 99.8, 98.8, and 95.4%, respectively. Efficient extraction by the quercetin‐imprinted polymer of epicatechin, catechin, and quercetin from an apple‐flavored black tea sample was achieved, with GC–MS employed for compound identification for both the tea and extracted samples.