氨基硅球表面印迹牛血清白蛋白分离条件的初步探讨

采用固定模板蛋白表面印迹的方法,在氨丙基衍生的硅球表面制备溶胶-凝胶印迹聚合物识别牛血清白蛋白.以该体系为例对制备蛋白质印迹聚合物的各个基本参数与分离选择性的关系进行研究.结果表明,用正辛基三甲氧基硅烷、氨丙基三乙氧基硅烷、四乙氧基硅烷在摩尔比为42.5:42.5:15,酸度为pH 7.0时进行聚合,并采用01 mol/L NaOH与10%(V/V) HAc-10%(m/V) SDS联用的方法洗脱固定的模板蛋白,由此制备的印迹聚合物的分离选择性能较好;并初步讨论了识别蛋白质的机理.     

介孔印迹聚合物的制备及固相萃取黄花蒿中的青蒿素

制备了一种基于分子印迹聚合物(MIP)的固相萃取填料,用于中草药黄花蒿中青蒿素(ARS)的分离纯化。采用青蒿素为模板分子,丙烯酰胺(AM)、甲基丙烯酸(MAA)为双功能单体,介孔材料(MCM-41型)为载体,表面印迹法制备ARS分子印迹聚合物。通过傅里叶变换红外光谱(FTIR)、透射电镜(TEM)、N_2吸附(BET)法对聚合物进行了表征,聚合物具有规则的形貌,较大的比表面积;动力学吸附和选择性吸附实验对MIP的吸附性能进行评价,结果表明,聚合物对青蒿素具有较高的吸附量(102.25 mg/g);能够快速达到吸附平衡(35 min);该聚合物为青蒿素的分离、富集提供一种新材料。     

核-壳型苏丹红Ⅰ印迹聚合物微球制备及应用研究

以苏丹红Ⅰ为模板分子,苯基-三甲氧基硅烷(PTMOS)为功能单体,乙二醇二甲基丙烯酸酯(EGD-MA)为交联剂,偶氮二异丁腈(AIBN)为引发剂,采用表面分子印迹技术,在自制的SiO2微球表面成功合成了对苏丹红Ⅰ具有良好选择识别性能的核-壳型印迹聚合物。采用红外光谱和扫描电子显微镜对分子印迹微球进行表征,结果表明该印迹聚合材料壳层厚度约为150 nm;采用静态吸附实验研究印迹材料对模板聚合物的吸附性能和选择特性,结果表明以PTMOS为功能单体的印迹聚合物对苏丹红Ⅰ具有优异的选择吸附性,其分离选择因子为2.62。在吸附过程中,模板分子苏丹红Ⅰ与印迹聚合物形成2种结合位点,2种结合位点的解离常数分别为2.30、10.78 mmol/L,最大表观结合量分别为27.40、128.53μmol/g。将该印迹聚合物作为固相萃取材料,对样品进行固相萃取,结合液相色谱技术成功用于辣椒油中苏丹红Ⅰ的测定。     

分子印迹固相萃取技术检测江水、尿液及牛奶中雌激素残留

以β-雌二醇和炔雌醇的分子印迹聚合物为填料制备固相萃取小柱,选择60%(V/V)甲醇-水溶液作为雌激素的淋洗液,甲醇-乙酸(9:1,V/V)为洗脱液,洗脱两次可彻底洗脱固相萃取小柱中目标分子.以建立的萃取条件对上海黄浦江水、尿液、牛奶中雌激素进行富集,结合高效液相色谱法,建立了基于分子印迹固相萃取技术检测上述实际样品中...     

核-壳型过氧化苯甲酰印迹溶胶-凝胶聚合物的制备及应用

以过氧化苯甲酰为模板分子,采用溶胶-凝胶印迹技术在自制的二氧化硅微球表面成功制备对过氧化苯甲酰具有特异性吸附能力的核-壳型印迹材料,并由红外光谱、扫描电镜和差热分析表征了印迹聚合物。该印迹微聚合物分散性好、热稳定好、平均粒径为300nm,印迹聚合物的壳层厚度为50nm。用高效液相色谱研究了印迹聚合物的吸附性能,结果表明该印迹聚合物对过氧化苯甲酰的选择系数为6.59。作为固相萃取材料,该印迹材料已被成功用于面粉中过氧化苯甲酰的分离和富集,回收率为94.98%。     

儿茶素活性成分分子印迹聚合物的固相萃取研究

以表没食子儿茶素没食子酸酯(Epigallocatechin-gallate,EGCG)为模板分子,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,在光冷引发条件下合成EGCG分子印迹聚合物,利用该聚合物制成分子印迹固相萃取柱,用于固相萃取茶叶提取物茶多酚,对萃取柱中的清洗液、洗脱剂、上载量等进行了选择.结果表明,在萃取柱上载样品之后,先用V(甲醇):V(水)＝1:9溶液进行清洗,再用V(甲醇):V(乙酸)＝9:1混合液进行目标分子的洗脱,可以得到比较纯的目标物质EGCG(色谱峰相对峰面积达92.4%),萃取柱在上载样品并进行清洗、洗脱之后,EGCG的回收率达69.3%.分子印迹柱具有较好的稳定性和耐用性能,使用20次后其选择性识别能力仍未降低,但空白印迹柱却没有这样的选择性识别能力.     

2-异戊基环戊酮虚拟模板印迹微球的制备及其吸附性能

以2-异戊基环戊酮为虚拟模板,采用沉淀聚合法制备了粒径20~50 μm的分子印迹微球。 用傅里叶变换红外光谱(FTIR)和扫描电子显微镜(SEM)研究了分子印迹微球的表面化学特征及粒径分布,测试了印迹聚合物对玫瑰醚的吸附动力学、等温吸附性能及吸附选择性。 考察了分子印迹固相萃取玫瑰醚的应用效能。 结果表明:分子印迹聚合物(MIPs)对玫瑰醚的吸附可在25 min达到平衡,具有较快的吸附动力学,一级动力学模型更适合描述其吸附动力学行为。 Freundlich模型最适合描述MIPs对玫瑰醚的等温吸附行为,聚合物材料最大的印迹位点数目为149.3 μmol/g。 聚合物对玫瑰醚的平均吸附能为166 kJ/mol,表明主要为化学吸附。 虚拟模板印迹聚合物对玫瑰醚的选择因子相对于香叶醇和香茅醇分别为3.710和5.636,且对含玫瑰醚的混合物中的目标化合物仍具有较高的选择吸附能力(竞争吸附量为18.02 mg/g)。 在优化洗涤(1 mL乙腈+1 mL乙腈和水混合溶剂(体积比9.5:0.5)+2 mL乙腈、甲醇和水混合溶剂(体积比8:1:2)和洗脱(3 mL甲醇和醋酸混合溶剂(体积比9:1))条件下,通过分子印迹固相萃取可实现玫瑰醚的有效分离和富集,回收率为96.23%。     

牛血红蛋白印迹聚合物的制备及其对牛血红蛋白的吸附特性

以牛血红蛋白为模板分子,丙烯酰胺为功能单体,N,N’-亚甲基双丙烯酰胺为交联剂,采用醛基硅胶表面修饰技术,合成了牛血红蛋白印迹聚合物（MIP）,并研究了该印迹聚合物对牛血红蛋白的吸附特性。结果表明:当洗脱时间为8 h、洗脱率为83.53%时,印迹聚合物对牛血红蛋白的吸附量为81.39 mg·g^-1。     

红霉素分子印迹聚合物微球的制备及性能研究

以红霉素为模板分子,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,在水相中采用悬浮聚合法制备了红霉素分子印迹聚合物微球。利用扫描电镜对其表面形貌进行了表征,探讨了不同分散剂浓度、水油比、搅拌速度等参数对聚合物微球粒径及粒径分布的影响,重点对聚合工艺进行了优化,并将所得的聚合物用作吸附剂研究了其分子识别与选择性能。研究表明,该方法合成的聚合物微球平均粒径为40~130μm,对模板分子具有较高吸附性能和选择性识别能力,其分离因子达1.83,而动态吸附饱和吸附量则达到了42.59μmol/g。     

槲皮素表面分子印迹聚合物的制备及其应用研究

以接枝双键的凹凸棒土(TM)为载体,槲皮素为模板分子,采用表面印迹技术制备对槲皮素具有特异吸附性能的分子印迹聚合物(MIP)。利用光谱法选择实验条件及对化合物表征。采用静态法研究聚合物对槲皮素的结合性能与识别性能。结果表明,该分子印迹材料对槲皮素具有特异的识别特性和优良的亲和性,提高了传统聚合物的结合率。以该印迹聚合物为固相萃取材料,结合高效液相色谱法,对白菜中的槲皮素进行分离富集,方法回收率为84.0%~90.6%,相对标准偏差低于5.6%。     

咖啡因分子印迹固相萃取柱的制备及应用

以咖啡因作为模板分子,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,制备了咖啡因分子印迹聚合物(MIP)。与非印迹聚合物(NIP)相比,MIP对咖啡因具有更高的吸附容量和选择性,MIP和NIP对咖啡因的最大静态吸附量分别为28.1和16.5mg/g,相对选择因子为1.25。以咖啡因分子印迹聚合物为固相萃取填料,结合高效液相色谱(HPLC),建立了茶水中咖啡因浓度及人饮茶后血清中咖啡因浓度的检测方法。考察了洗脱剂种类和用量对咖啡因回收率的影响。当萃取柱依次以2mL水活化,水溶液上样,2mL水淋洗,6mL甲醇-乙酸(9∶1,V/V)洗脱,咖啡因在MIP固相萃取柱上的回收率达到97.5%,而在NIP柱上的回收率仅为54.9%。     

Imprinted Polymer Particles for Aluminum Uptake: Synthesis and Analytical Applications

This work reports the preparation of molecularly imprinted polymer (MIP) particles for selective extraction and determination of aluminum ion from aqueous media. Polymerization was achieved in a glass tube containing AlCl₃, morin, 4-vinylpyridine, ethyleneglycoldimethacrylate, 2,2′ - azobisisobutyronitrile. The polymer block obtained was ground and sieved (55–75 μ m) and the Al (III)-morin complex was removed from polymer particles by leaching with 2 M of HCl, which leaves a cavity in the polymer particles. The polymer particles, both prior to and after leaching, have been characterized by IR and differential scanning calorimetry (DSC) studies. The effect of different parameters, such as pH, adsorption and desorption time, type and least amount of eluent for elution of complex from polymer were evaluated. Extraction efficiencies more than 99% were obtained by elution of the polymers with 15 mL of methanol-acetonitrile mixture (1:2) followed by ICP-OES. The limit of detection of the proposed method was 3.5 μ g L^?1. A dynamic linear range (DLR) in the range of 20 to 200 μ g L^?1 was obtained. The relative standard deviation (RSD) was less than 6.5%. The influence of various cationic and anionic interferences on percent recovery of complex was studied. The method was applied to the recovery and determination of aluminum in different real samples.     

Molecularly imprinted polymers for on-line clean up and preconcentration of chloramphenicol prior to its voltammetric determination

The performance of a molecularly imprinted polymer (MIP) as a selective solid-phase extraction sorbent for the clean-up and preconcentration of the antibiotic chloramphenicol is described. The MIP was prepared using chloramphenicol as the template, (diethylamino)ethyl methacrylate as the functional monomer, and ethylene glycol dimethacrylate as the cross-linking monomer, and using tetrahydrofuran as the solvent. Detection of chloramphenicol was carried out by square-wave voltammetry at electrochemically activated carbon fiber microelectrodes. Chloramphenicol was eluted from the MIP microcolumn with methanol. Different experimental variables (sample pH, eluent volume, analyte and eluent flow rates and sample volume) associated with the rebinding/elution process were optimized. For a 250 mL sample, a nominal enrichment factor of 500 was attained, and for a chloramphenicol concentration of 3.0x10(-8) mol L(-1) (9.7 microg L(-1)) a recovery of 96+/-4% was obtained. A range of linearity for chloramphenicol between 3.0x10(-8) and 1.0x10(-5) mol L(-1) was obtained by loading 17 mL of analyte solutions of different concentration, eluting with 0.5 mL methanol, evaporating under a stream of nitrogen and dissolving the residue in phosphate buffer of pH 7.8. The MIP selectivity was evaluated by checking several substances with similar molecular structures to that of chloramphenicol. The applicability of the MIP for both clean up and preconcentration was demonstrated by determining chloramphenicol in ophthalmic solutions and spiked milk at different concentration levels.     

Molecularly imprinted on-line solid-phase extraction combined with flow-injection chemiluminescence for the determination of tetracycline

A molecularly imprinted polymer solid phase extraction (MISPE) method combined with flow-injection chemiluminescence (FI-CL) for the determination of residual tetracycline (TC) in fish samples is presented. The molecularly imprinted polymer (MIP) of TC was synthesized and particles of this MIP were packed into a polytetrafluoroethylene (PTFE) tube, which was connected into the sampling loop of an eight-way injection valve and served as the MISPE column for on-line selective adsorption of TC. The eluent (CH3CN : HNO3 (0.01 mol L(-1)) = 4 ratio 1, v ratio v) was used for extracting the adsorbed TC, which could be detected by its good enhancing effect on the CL reaction between Ce(iv) and rhodamine B. The CL intensity is linear to TC concentration in the range from 4 x 10(-9) to 4 x 10(-7) g mL(-1). The detection limit is 1 x 10(-9) g mL(-1) (3 sigma) and the relative standard deviation is 2.4% (n = 9). The conditions of preconcentration, extraction and CL reaction were carefully studied. The selectivity experiment shows that the selectivity and sensitivity of the CL method could be improved greatly when MIP was used as a recognition material in SPE. However, the MISPE column interacted indiscriminately with oxytetracycline (OTC) with a 49 +/- 2% binding. An intermediate differential pulsed elution (DPE) step using 3% acetic acid as eluent was employed to remove OTC and other interfering substances. The proposed MISPE-CL method has been applied successfully to the determination of TC in fish samples. At the same time, the binding characteristics of the polymer to tetracycline were evaluated by batch and dynamic methods.     

Extraction of clenbuterol from calf urine using a molecularly imprinted polymer followed by quantitation by high-performance liquid chromatography with UV detection

A method for the extraction of clenbuterol from calf urine samples using a molecularly imprinted polymer (MIP) has been developed. The aim was that the final extracts from the MIP should allow quantitation of clenbuterol down to 0.5 ng/mL urine using HPLC with UV detection. The MIP was produced using brombuterol as a template and the selectivity of the MIP, for clenbuterol, was tested against a non-imprinted polymer (produced without template) and was found to be high. After loading of 5 mL diluted centrifuged urine, selective binding was established in acetonitrile-acetic acid (98:2). For further elution of interferences, 0.5 M ammonium acetate buffer pH 5 and 70% acetonitrile in water was used. Clenbuterol was eluted using 1% trifluoroacetic acid in methanol, which was evaporated and reconstituted in buffer. Results from the HPLC analyses showed that the extraction of clenbuterol using MIP is linear in the range 0.5-100 ng/mL with good precision (4.3% for 0.6 ng/mL and 2.1% for 6.0 ng/mL) and accuracy (96.7% for 0.6 ng/mL and 96.7% for 6.0 ng/mL). The recoveries were 75%. The results show that the method offers a selectivity and sensitivity that make the quantitation of 0.5 ng clenbuterol/mL urine by HPLC-UV possible and a competitive alternative to state-of-the-art routine analytical methods.     

Extraction of crocin from saffron (Crocus sativus) using molecularly imprinted polymer solid‐phase extraction

A new molecularly imprinted polymer for extraction of crocin from saffron stigmas was prepared using gentiobiose (a glycoside moiety in crocin structure) as a template. Crocin binding to gentiobiose imprinted polymer (Gent‐MIP) was studied in comparison with a blank nonimprinted polymer in aqueous media. Affinity of the Gent‐MIP for the crocin was more than the nonimprinted polymer at all concentrations. In Scatchard analysis, the number of binding sites in each gram of polymer (maximum binding sites) and dissociation constant of crocin to binding sites were 18.4 μmol/g polymer and 11.2 μM, respectively. The Gent‐MIP was then used as the sorbent in an SPE method for isolation and purification of crocin from methanolic extract of saffron stigmas. The recovery of crocin, safranal and picrocrocin was determined in washing and elution steps. The Gent‐MIP had significantly higher affinity for crocin than other compounds and enabled selective extraction of crocin with a high recovery (84%) from a complex mixture. The results demonstrated the possibility of using a part of a big molecule in preparing a molecularly imprinted polymer with a good selectivity for the main structure.     

Application of non-specific fluorescent dyes for monitoring enantio-selective ligand binding to molecularly imprinted polymers

The displacement of non-specific dyes from molecularly imprinted polymer (MIP) chromatographic stationary phases has been used for the detection and quantification of ligand-polymer binding events. A blank polymer and an L-phenylalaninamide-imprinted polymer were prepared using methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as a crosslinker. The MIP is first loaded with dye, and a solution of the dye in the eluent is passed through the MIP. If analyte is injected into the dye solution in the eluent, part of the dye is competitively replaced by the analyte from the MIP. Specifically, the competitive displacement of rhodamine B by amino acids and phenylalaninamide (Phe-NH₂), respectively, has been studied under polar and hydrophobic elution conditions. Enantioselective binding of Phe and Phe-NH₂ to the imprinted polymer was shown to occur in the micromolar concentration range. It is proposed that the displacement of non-specific dyes from MIPs be used for the development of multisensors based upon these highly specific and stable materials, which provide promising alternatives to the use of biological macromolecules in sensor technology. Received: 24 November 1998 / Revised: 29 January 1999 / Accepted: 2 February 1999     

Application of non-specific fluorescent dyes for monitoring enantio-selective ligand binding to molecularly imprinted polymers

The displacement of non-specific dyes from molecularly imprinted polymer (MIP) chromatographic stationary phases has been used for the detection and quantification of ligand-polymer binding events. A blank polymer and an L-phenylalaninamide-imprinted polymer were prepared using methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as a crosslinker. The MIP is first loaded with dye, and a solution of the dye in the eluent is passed through the MIP. If analyte is injected into the dye solution in the eluent, part of the dye is competitively replaced by the analyte from the MIP. Specifically, the competitive displacement of rhodamine B by amino acids and phenylalaninamide (Phe-NH₂), respectively, has been studied under polar and hydrophobic elution conditions. Enantioselective binding of Phe and Phe-NH₂ to the imprinted polymer was shown to occur in the micromolar concentration range. It is proposed that the displacement of non-specific dyes from MIPs be used for the development of multisensors based upon these highly specific and stable materials, which provide promising alternatives to the use of biological macromolecules in sensor technology. Received: 24 November 1998 / Revised: 29 January 1999 / Accepted: 2 February 1999     

Preparation and utilization of a molecularly imprinted polymer for solid phase extraction of tramadol

In this paper, a highly selective molecularly imprinted polymer (MIP) for tramadol hydrochloride, a drug used to treat moderate to severe pain, was prepared and its use as solid-phase extraction (SPE) sorbent was demonstrated. The molecularly imprinted solid-phase extraction procedure followed by high performance liquid chromatography with ultraviolet detector (MISPE-HPLC) was developed for selective extraction and determination of tramadol in human plasma and urine. The optimal conditions for molecularly imprinted solid-phase extraction (MISPE) consisted of conditioning with 1 mL methanol and 1 mL of deionized water at neutral pH, loading of tramadol sample (50 μg L⁻¹) at pH 7.5, washing using 1 mL acetone and elution with 3 × 1 mL of 10% (v/v) acetic acid in methanol. The MIP selectivity was evaluated by checking several substances with similar molecular structures to that of tramadol. Results from the HPLC analyses showed that the calibration curve of tramadol (using MIP from human plasma and urine) is linear in the ranges of 6–100 and 3–120 μg L⁻¹ with good precisions (1.9% and 2.9% for 5.0 μg L⁻¹), respectively. The recoveries for plasma and urine samples were higher than 81%.      

Molecularly imprinted polymers for the selective solid-phase extraction of chloramphenicol

A variety of bulk polymers for the selective separation of chloramphenicol were synthesised from 2-vinylpyridine, diethylaminoethyl methacrylate or methacrylic acid monomers. Chromatographic evaluation indicated that chloramphenicol was retained under nonpolar elution conditions (k = 58.65) through selective hydrogen bonding and ionic interactions. The retention of chloramphenicol under aqueous elution conditions (k > 100) results from nonselective hydrophobic interactions. Under nonpolar elution conditions, the functional monomer employed imparted a significant influence on the recognition properties of the corresponding polymer. After solid-phase extraction using a molecularly imprinted polymer as sorbent and either an organic or aqueous washing solvent, nearly 100% recovery from the chloramphenicol standard solution was achieved, and nearly 90% recovery could be attained from spiked honey samples. The molecularly imprinted polymer was well suited to suppress matrix effects, and provided optimal preconcentration of the target molecule (chloramphenicol) prior to chromatographic analysis.