可逆加成-断裂链转移策略制备可识别转铁蛋白的抗原决定基印迹微球

应用可逆加成-断裂链转移（RAFT）策略制备了一种抗原决定基表面印迹微球。这一工作以转铁蛋白的抗原决定基N端九肽作为模板,通过共价键合的方式固载于修饰了戊二醛的硅胶颗粒表面。然后以甲基丙烯酸、甲基丙烯酰羟乙酯为功能单体,甲叉基双丙烯酰胺为交联剂,偶氮二异丁腈（AIBN）为引发剂,N,N-二甲基甲酰胺为溶剂,在三硫酯试剂2-（十二烷基三硫代碳酸酯基）-2-甲基丙酸的调控下,于70 ℃进行活性-可控的聚合反应,制备得到分子印迹微球。该材料对模板抗原决定基的识别容量为2.36 mg/g,印迹因子为1.89;对转铁蛋白的识别容量为4.98 mg/g,印迹因子为1.61,120 min内可达到吸附平衡;在多蛋白质竞争识别中,该材料对转铁蛋白识别的印迹因子远高于细胞色素C、乳球蛋白等其他竞争蛋白质的印迹因子。以上结果证明,通过RAFT策略制备得到的抗原决定基分子印迹材料在对抗原决定基具有良好的识别能力的同时,对模板抗原决定基对应的转铁蛋白也具有优良的选择性、较高的识别容量和较快的识别速度。     

Sieving polymer synthesis by reversible addition fragmentation chain transfer polymerization

Replaceable sieving polymers are the fundamental component for high‐resolution nucleic acids separation in CE. The choice of polymer and its physical properties play significant roles in influencing separation performance. Recently, reversible addition fragmentation chain transfer (RAFT) polymerization has been shown to be a versatile polymerization technique capable of yielding well‐defined polymers previously unattainable by conventional free‐radical polymerization. In this study, a high molecular weight poly‐(N,N‐dimethylacrylamide) (PDMA) at 765 000 gmol^?1 with a polydispersity index of 1.55 was successfully synthesized with the use of chain transfer agent—2‐propionic acidyl butyl trithiocarbonate in a multistep sequential RAFT polymerization approach. This study represents the first demonstration of RAFT polymerization for synthesizing polymers with the molecular weight range suitable for high‐resolution DNA separation in sieving electrophoresis. Adjustment of pH in the reaction was found to be crucial for the successful RAFT polymerization of high molecular weight polymer as the buffered condition minimizes the effect of hydrolysis and aminolysis commonly associated with trithiocarbonate chain transfer agents. The separation efficiency of 2‐propionic acidyl butyl trithiocarbonate PDMA was found to have marginally superior separation performance compared to a commercial PDMA formulation, POP?‐CAP, of similar molecular weight range.     

伊诺沙星分子印迹聚合物的制备及分子识别性能研究

以伊诺沙星为印迹分子、甲基丙烯酸为功能单体、季戊四醇三丙烯酸酯为交联剂,合成了对伊诺沙星有较好选择性的印迹聚合物。利用铽敏化荧光,通过静态平衡结合法和Scatchard分析法研究了此印迹聚合物的结合能力和选择性,结果表明印迹聚合物对伊诺沙星有较高的亲和性和选择性。     

Synthesis and characterization of molecularly imprinted polymers for recognition of ciprofloxacin

A molecularly imprinted polymer (MIP), with special molecule recognition properties of ciprofloxacin (CIP), was prepared by thermal polymerization in which ciprofloxacin acted as template molecule, α-methacrylic acid (MAA) acted as functional monomer and trimethylolpropane trimethylacrylate (TRIM) acted as crosslinker. The optimized ratio was determined to be n(CIP): n (MMA):n(TRIM)51:6:16 by investigation of the effects of different concentrations of functional monomer and the crosslinker on the MIP’s recognition properties. Equilibrium binding experiment was used to investigate the adsorption dynamics, the binding ability to template molecule and the substrate selectivity. Scatchard analysis was used to study the MIP’s binding characteristic to template molecule. The results indicated that MIP has higher adsorption ability and selectivity. The equilibrium distribution coefficient K _D was 41.64 and the separation factor α was 1.62. Scatchard analysis showed that two different kinds of binding sites were produced in the polymer matrix and their dissociation constants were calculated to be K _d1 = 5.249 × 10⁻⁵ mol·L⁻¹, K _d2 = 2.237 × 10⁻³ mol·L⁻¹. __________ Translated from Chemistry, 2008, 71(2): 132–137     

Simple and selective extraction of quercetin with microextraction in packed syringe method using modified glass powder by a molecularly imprinted polymer followed by spectrophotometric determination

A new sample preparation method based on microextraction in packed syringe was developed for preconcentration of quercetin prior to its spectrophotometric determination. Molecularly imprinted polymers as packing material was used for higher extraction efficiency. First, glass powder as support material because of low cost and available substrate was modified, and then molecularly imprinted polymers were synthesized by the sol–gel method using 3-aminopropyltriethoxysilane as a functional monomer and tetraethyl orthosilicate as cross-linker agent. The combination of a molecularly imprinted polymers and microextraction in packed syringe increased the selectivity and sensitivity. The surface morphology and functionality of the prepared molecularly imprinted polymers was characterized using Fourier-transform infrared spectroscopy, Field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and thermogravimetric analysis. Different influencing parameters on extraction efficiency such as effect of the number of sample sorption/desorption cycles, type and volume of desorption solvent, pH of the sample solution, and molecularly imprinted polymers amounts were optimized. Under the optimum condition, the proposed method displayed a linear range from 0.01 to 5 µg mL⁻¹ and limit of detection 3.68 ng mL⁻¹. Relative standard deviation for three replicate determination of 1 µg mL⁻¹ quercetin was 2.1 %. The proposed method was applied successfully for the selective extraction of quercetin from tea and coffee samples.     

S-布洛芬磁性分子印迹膜的吸附及拆分性能

以S-布洛芬为模板分子、3-氨丙基三乙氧基硅烷为功能单体、正硅酸乙酯为交联剂,采用溶胶凝胶法成功制备了对S-布洛芬具有特异选择识别功能的磁性分子印迹聚合物,并且分别采用红外(IR)光谱、扫描电镜(SEM)、X射线粉末衍射(XRD)对其结构进行了表征.通过紫外(UV)光谱研究了其对S-布洛芬的吸附性能,并且建立了高效液相色谱(HPLC)手性流动相法研究其对布洛芬的拆分.结果表明,该磁性分子印迹聚合物具有良好的磁响应性,在外加磁场下可实现快速分离;S-布洛芬分子印迹复合膜对S-布洛芬具有较好的选择结合性,其结合量达到68.3mg/g;每100mg复合膜可使外消旋布洛芬的分离度增加2.1%.     

替米考星磁性表面分子印迹聚合物的制备及应用

报道了一种替米考星磁性表面分子印迹聚合物吸附剂。它以Fe₃O₄@SiO₂为磁性基质，替米考星为模板分子，甲基丙烯酸为功能单体，通过硅烷化反应在Fe₃O₄@SiO₂表面键合上3-（甲基丙烯酰氧）丙基三甲氧基硅烷制备得到。该吸附剂对大环内酯类抗生素表现出高选择性和高富集能力（对4种模型大环内酯的富集倍数为212~675倍）。相比传统的非表面分子印迹聚合物，吸附平衡时间可缩短为30 min，可以重复使用至少6次；结合高效液相色谱-紫外检测，将该吸附剂应用于奶粉中4种大环内酯类抗生素的残留检测，所得检出限和定量限分别为0.58~1.36 μg/kg和1.92~4.55 μg/kg，日内（n=5）和日间（n=3）回收率在83.2%~123.0%之间，RSD均小于12.2%。     

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。     

Ordered macroporous quercetin molecularly imprinted polymers: Preparation,characterization, and separation performance

Ordered macroporous molecularly imprinted polymers were prepared by a combination of the colloidal crystal templating method and the molecular imprinting technique by using SiO₂ colloidal crystal as the macroporogen, quercetin as the imprinting template, acrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross‐linker and tetrahydrofuran as the solvent. Scanning electron microscopy and Brunauer–Emmett–Teller measurements show that the ordered macroporous molecularly imprinted polymers have a more regular macroporous structure, a narrower pore distribution and a greater porosity compared with the traditional bulk molecularly imprinted polymers. The kinetic and isothermal adsorption behaviors of the polymers were investigated. The results indicate that the ordered macroporous molecularly imprinted polymers have a faster intraparticle mass transfer process and a higher adsorption capacity than the traditional bulk molecularly imprinted polymers. The ordered macroporous molecularly imprinted polymers were further employed as a sorbent for a solid‐phase extraction. The results show that the ordered macroporous molecularly imprinted polymers can effectively separate quercetin from the Gingko hydrolysate.     

Surface morphology of spin‐coated molecularly imprinted polymer films

The surface morphology of thin molecularly imprinted polymer films has been studied using atomic force microscopy (AFM). The films were produced by spin coating onto glass substrates and examined as a function of host polymer, imprinting template, casting solvent, spin‐coater rotation speed and post‐production treatment. It was observed that the gross features of such films are template controlled. The fine structure is determined by parameters such as solvent, spin speed or subsequent treatment. The relationship between these observations, polymer–template interactions and the mechanism of film formation in spin coating is discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and characterization of surface‐initiated polymer brushes on silicon substrates by reversible addition fragmentation chain transfer polymerization

Polymer brushes were prepared by using the reversible addition fragmentation chain transfer (RAFT) technique. The silicon substrates (Si (111) surface) were modified with ethyl xanthate groups which were introduced by the treatment of Si (111) surface with sodium ethyl xanthate. The polymer brushes were then prepared under RAFT conditions from the Si (111) wafer. Its “living” characteristics were determined by a series of characterizations including gel permeation chromatography (GPC), ellipsometry, and contact angle measurements. The results showed a well‐defined graft layer consisting of polymer brushes with low‐polydispersity could be prepared directly on Si (111)‐X surface (where X represents an ethyl xanthate groups). The structure of the polymer brushes was characterized and confirmed with the surface sensitive techniques such as X‐ray photoelectron spectroscopy (XPS) and scanning probe microscopy (SPM). Copyright © 2007 John Wiley & Sons, Ltd.     

Isoprene polymerization via reversible addition fragmentation chain transfer polymerization

Until recently, the primary living radical polymerization method available for preparing polyisoprene was nitroxide‐mediated radical polymerization, with reversible addition‐fragmentation chain transfer polymerization being applied only in a few cases within the last couple of years. We report here the preparation of polyisoprene by RAFT in the presence of the trithiocarbonate transfer agent S‐1‐dodecyl‐S′‐(r,r′‐dimethyl‐r′′‐acetic acid)trithiocarbonate and t‐butyl peroxide as the radical initiator. The kinetics of this polymerization at an optimized temperature of 125 °C and radical initiator concentration of 0.2 equiv relative to transfer agent have been studied in triplicate and demonstrate the living nature of the polymerization. These conditions resulted in polymers with narrow polydispersity indices, on the order of 1.2, with monomer conversions up to 30%. Retention of chain‐end functionality was demonstrated by polymerizing styrene as a second block from a polyisoprene macrotransfer agent, resulting in a block copolymer presenting a unimodal gel permeation chromatogram, and narrow molecular weight distribution. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4100–4108, 2007     

Preparation and characterization of a novel molecularly imprinted polymer for the separation of glycyrrhizic acid

Molecularly imprinted polymers of glycyrrhizic acid were prepared by solution polymerization using glycyrrhizic acid as the template molecule, N‐vinypyrrolidone as functional monomer, N ,N‐methylene bisacrylamide as cross‐linker and ascorbic acid and hydrogen peroxide as initiators. Focused on the adsorption capacity and separation degree of the polymer to glycyrrhizic acid, the effects of the monomers, crosslinker and initiators were investigated and optimized. Finally, the structure of the polymer was characterized by using Fourier transform infrared spectroscopy and scanning electron microscopy. To obtain objective results, non‐imprinted molecular polymers prepared under the same conditions were also characterized. The adsorption quantity of the polymer was measured by high‐performance liquid chromatography. Under the optimum conditions, the maximum adsorption capacity of glycyrrhizic acid approached 15 mg/g, and the separation degree was as high as 2.5. The adsorption kinetics could be well described by a pseudo‐first‐order model, while the thermodynamics of the adsorption process could be described by the Langmuir model.     

核壳结构的萘夫西林磁性分子印迹聚合物微球的制备及性能

以表面修饰双键的Fe₃O₄@SiO₂纳米颗粒为基体,以萘夫西林(nafcillin)为模板,甲基丙烯酸(MAA)为单体,乙二醇二甲基丙烯酸酯(EGDMA)为交联剂,偶氮二异丁腈(AIBN)为引发剂,采用三步升温聚合法合成了核壳结构的萘夫西林磁性分子印迹聚合物。采用傅里叶变换红外光谱仪(FT-IR)、透射电子显微镜(TEM)、X射线衍射仪(XRD)和振动样品磁强计(VSM)对制备的印迹聚合物微球进行了表征,得到的磁性印迹聚合物微球的粒径在320 nm左右,大小均匀,分散性较好,可以在外加磁场下与溶剂实现快速分离。对磁性印迹和非印迹聚合物进行了吸附性能研究,结果表明该印迹聚合物微球对模板分子具有很高的吸附容量(50.7 mg/g),特异性识别性能良好(印迹因子为2.46),有望应用于实际样品中萘夫西林残留量的富集分析。     

Improvement of extraction capability of magnetic molecularly imprinted polymer beads in aqueous media via dual-phase solvent system

In this study, a novel and simple dual-phase solvent system for the improvement of extraction capability of magnetic molecularly imprinted polymer (MIP) beads in aqueous sample was proposed. The method integrated MIP extraction and micro-liquid-liquid extraction (micro-LLE) into only one step. A magnetic MIP beads using atrazine as template was synthesized, and was applied to aqueous media by adding micro-volume of n-hexane to form a co-extraction system. The magnetic MIP beads preferred to suspend in the organic phase, which shielded them from the disturbance of water molecule. The target analytes in the water sample was extracted into the organic phase by micro-LLE and then further bound to the solid-phase of magnetic MIP beads. The beads specificity was significantly improved with the imprinting efficiency of template increasing from 0.5 to 4.4, as compared with that in pure aqueous media. The extraction capacity, equilibration process and cross-selectivity of the MIP dual-phase solvent extraction system were investigated.The proposed method coupled with high-performance liquid chromatography was applied to the analysis of atrazine, simazine, propazine, simetryn, prometryne, ametryn and terbutryn in complicated sample such as tomato, strawberry juice and milk. The method is selective, sensitive and low organic solvent-consuming, and has potential to broaden the range of MIP application in biological and environmental sample.     

Rapid determination of antiviral medication ribavirin in different feedstuffs using a novel magnetic molecularly imprinted polymer coupled with high‐performance liquid chromatography

A novel magnetic molecularly imprinted polymer adsorbing material was successfully synthesized to detect ribavirin in animal feedstuff. Molecularly imprinted polymer was prepared through surface polymerization by using ribavirin as template molecule, methyl methacrylate, and γ‐methacryloxypropyl trimethoxy silane functionalized magnetic mesoporous silica as bifunctional monomers, and ethylene diglycidyl ether as crosslinking agent. The prepared magnetic molecularly imprinted polymer was characterized by scanning electron microscopy and infrared spectroscopy. Static and dynamic adsorption experiments and selective adsorption analysis were performed to evaluate the adsorption and selectivity of magnetic molecularly imprinted polymer. Different experiments were conducted to optimize the magnetic solid‐phase extraction conditions. Under optimal experimental conditions, a magnetic molecularly imprinted solid‐phase extraction coupled with high‐performance liquid chromatography method was successfully developed for ribavirin detection. The established method achieved a satisfactory linear range of 0.20–50 mg/L (R² > 0.99) and a low detection limit (0.081 mg/kg). An average recovery of 92–105% with relative standard deviation of <6.5% was obtained upon the application of the developed method to detect ribavirin in real feedstuff samples. Thus, established method can be used for the rapid and simple separation and detection of added ribavirin in feedstuff.     

Sensitive and selective determination of imidacloprid with magnetic molecularly imprinted polymer by using LC/Q-TOF/MS

In this paper, magnetic-molecularly imprinted polymer was used for the preconcentration of trace levels of imidacloprid in water and apple samples prior to liquid chromatography-quadrupole-time-of-flight mass spectrometric determination. The selectivity of the magnetic polymer was united with the sensitivity and the high resolving power of the chromatographic system. The developed method showed a linear range from 10.0 to 500.0 µg/L. The quantitative recoveries were obtained for water and apple samples in the range of 92.0%–99.0 %. The relative standard deviations of intra-day and inter-day tests were found to be in the range of 0.8%–1.2% and 1.2%–1.6 %, respectively. In addition, the same magnetic-molecularly imprinted polymer (MMIP) can be used at least ten cycles for the determination of imidacloprid. The preconcentration factor of the method was found to be 2.5, and the total preconcentration procedure can be completed in 1 h. Characterization of synthesised particles were executed with various techniques. Due to its suitable limit of detection, dynamic linear range, sensitivity and selectivity, the developed method seemed to be ideal for the determination and preconcentration of imidacloprid in water and fruit samples.     

A novel polymer dispersed liquid crystal film prepared by reversible addition fragmentation chain transfer polymerization

Polymer as an important component of polymer dispersed liquid crystal (PDLC) has a great influence on electro-optical properties. In this letter, the effect of molecular weight of polymer matrix on the electro-optical properties of PDLC films was investigated with reversible addition fragmentation transfer (RAFT) polymerization. It was found that the saturation voltage and memory effect were apparently influenced by molecular weight of polymer which can be regulated efficiently by irradiation time, while the morphology of liquid crystal droplets kept unaltered. It was estimated that the increase of molecular weight of polymer enhanced entanglement between polymer and liquid crystal, which induced the different surface interaction and electro-optical properties.     

环丙沙星分子印迹聚合物的合成及识别性能研究

采用分子印迹技术合成了以环丙沙星为印迹分子,以甲基丙烯酸和4-乙烯基吡啶同时为功能单体的分子印迹聚合物。运用平衡结合实验研究了印迹聚合物的吸附特性和选择识别能力。Scatchard分析表明,在所研究的浓度范围内,分子印迹聚合物中形成了两类不同的结合位点。底物选择实验表明,这种聚合物对环丙沙星呈现高的选择结合能力。     

螺旋霉素分子印迹磁性纳米吸附剂的合成及应用

制备了一种以螺旋霉素为模板分子的分子印迹磁性纳米吸附剂。以磁性纳米Fe₃O₄为内核,经丙烯酸表面修饰后再以螺旋霉素为模板分子、甲基丙烯酸为功能单体、乙二醇二甲基丙烯酸酯为交联剂,通过表面自由基聚合反应制备得到。该吸附剂对螺旋霉素、交沙霉素、替米考星和酒石酸泰乐菌素4种大环内酯类抗生素表现出良好的富集效果（富集倍数分别为310、118、758和72）,其选择性明显优于常规C₁₈吸附剂。该吸附剂可重复使用至少6次。结合高效液相色谱-紫外检测器建立了上述4种抗生素的分析方法。方法检出限为0.53~2.75 μg/L,定量限为1.78~9.16 μg/L;在50、100和150 μg/L低中高3个添加水平下,方法回收率在80.78%~123.02%之间,相对标准偏差<15.8%（n=5）。该方法被应用于分析蜂蜜中的上述4种抗生素。