温度驱动离子液体分散微萃取/超高压液相色谱检测水样中的微量四环素

建立了一种超高压液相色谱(UPLC)快速测定环境水样中8种痕量四环素的方法.利用稀土金属镧作为螯合试剂与水样中的四环素形成疏水性螯合物.温度驱动[Bmim]PF6分散萃取富集目标物,采用超高压液相色谱进行分离,紫外检测器检测,并对实验条件进行了优化.在最佳条件下,8种四环素在一定质量浓度范围内呈良好线性,r2均大于0....     

Synthesis and evaluation of tetracycline imprinted xerogels: comparison of experiment and computational modeling

A series of silica-based tetracycline (TC)-imprinted xerogel sorbents were prepared by sol-gel processing and were characterized for TC binding. Molecularly imprinted xerogels (MIXs) formed from allyltriethoxysilane (AtEOS) and tetraethoxysilane (TEOS) and end capped with trimethylchlorosilane exhibited the best analytical performance (imprinting factor, IF, of 7.46±0.13). Computational modeling was used to estimate the interaction energy (IE) between TC and each type of silane to evaluate our ability to predict the analytical performance of a given MIX. Rankings from the computations agreed with the experimental data showing the AtEOS having the highest IE in comparison to the other formulations. Together, these results demonstrate the potential and limitations of using theoretical calculations to guide the development of analyte selective MIXs in comparison to arbitrary trial and error approaches traditionally used to produce MIXs as sorbents for solid phase extraction.     

基于金属卟啉的分子印迹聚合物的合成及其对三唑类杀菌剂识别性能研究

以三唑类杀菌剂氟环唑为印迹分子,5-(4-甲基丙烯酰氧苯基)-10,15,20-三苯基卟啉锌为功能单体,乙二醇二甲基丙烯酸酯为交联剂,合成了新型的基于金属卟啉的分子印迹聚合物.紫外-可见光谱研究表明印迹分子与功能单体在聚合前形成1∶1配合物.通过选择性吸附和固相萃取表征研究了该印迹聚合物对氟环唑及具有类似化学结构的三唑类杀菌剂的识别能力,并与非印迹聚合物进行了比较,结果表明印迹聚合物具有良好的特异性识别性能,同时,印迹聚合物的交联度及吸附溶剂的极性对印迹效果有着显著影响.     

金属卟啉分子印迹聚合物的合成与性能研究

以5-(4-羟基苯基)-10,15,20-三苯基卟啉锌为印迹分子,4-乙烯基吡啶为功能单体,乙二醇二甲基丙烯酸酯为交联剂,合成了具有金属卟啉识别能力的分子印迹聚合物.紫外可见滴定光谱研究表明,功能单体与印迹分子在聚合前形成1:1的配合物.通过吸附试验、荧光光谱及斯卡查特分析法,考察了分子印迹聚合物对锌卟啉化合物的识别性能.结果表明,印迹聚合物对结构类似的卟啉化合物具有良好的识别能力,对印迹分子荧光性能的影响远大于其对应的非印迹聚合物.在浓度较低时,印迹聚合物对印迹分子的结合常数和最大结合量分别为:1.61×106L/mol和3.22×10-5mol/g.     

Sol–gel-based molecularly imprinted xerogel for capillary microextraction

A novel molecularly imprinted xerogel (MIX) based on organically modified silica (ORMOSIL) was successfully prepared for on-line capillary microextraction (CME) coupled with high-performance liquid chromatography (HPLC). The sol-gel-based xerogel was prepared using only one precursor and exhibited extensive selectivity towards triazines along with significant thermal and chemical stability. Atrazine was selected as a model template molecule and 3-(trimethoxysilyl)propylmethacrylate (TMSPMA) as a precursor in which the propylmethacrylate moiety was responsible for van der Waals, dipole-dipole, and hydrogen-bond interactions with the template. This moiety plays a key role in creation of selective sites while methoxysilyl groups in TMSPMA acted as crosslinkers between the template and the propylmethacrylate moiety. Moreover, a non-imprinted xerogel (NIX) was also prepared in the absence of the template for evaluating the extraction efficiency of the prepared MIX. Then, the prepared imprinted and non-imprinted xerogels were used for extraction of three selected analytes of triazines class including atrazine, ametryn, and terbutryn, which have rather similar structures. The extraction efficiency of the prepared xerogel for atrazine, the template molecule, was found to be ten times greater than the efficiency achieved by the non-imprinted one. In the meantime, the extraction efficiency ratio of MIX to NIX for ametryn and terbutryn was also rather significant (eight times). Moreover, other compounds from different classes including dicamba, mecoprop, and estriol were also analyzed to evaluate the selectivity of the prepared MIX towards triazines. The ratio of enrichment factors (EF) of MIX to NIX for atrazine, ametryn, terbutryn, dicamba, mecoprop, and estriol were about 10, 8, 8, 2, 2, and 3, respectively. The linearity for the analytes was in the range of 5-700 μg L(-1). Limit of detection was in the range of 1-5 μg L(-1) and the RSD% values (n = 5) were all below 6.6% at the 20 μg L(-1) level. The developed method was also applied to real water samples and the relative recovery percentages obtained for the spiked water samples were from 92 to 104%. The CME loop, containing the prepared MIX, exhibited a rather long life time due to its remarkable solvent and mechanical stability. Even after 100 runs, no decrease in the peak areas was observed. The developed method could easily provide the possibility of preparing a selective sorbent in a unique way with the lowest possible cost and time.     

模板效应对β分子筛中Al原子分布的DFT理论计算研究

基于量子化学中的密度泛函理论(DFT),通过β分子筛同模板剂四乙胺阳离子(TEA⁺)的主客体相互作用来讨论了模板剂分子对骨架Al的靶向作用。计算采用了密度泛函理论中的B3LYP方法在6-31G(d,p)基组上研究了β分子筛同TEA+主客体相互作用的几何结构、分子轨道、电荷分布以及9个不同骨架位置的相互作用能。研究结果表明：带正电荷的TEA⁺吸引β分子筛上Al原子形成的阴离子中心(Zeo-AlO₄^-),两者具有很好的匹配关系。通过主客体相互作用影响了Al原子在分子筛中的分布。骨架Al最有利于落位在β分子筛的T5和T6位,落位的稳定性顺序是Group Ⅱ(T5,T6)>Group Ⅲ(T7-T9)>Group Ⅰ(T1-T4)。     

Surfactant Templated Silica Xerogels as Adsorbents for Rhodamine 6G

A series of silica xerogels was synthesized by using TEOS as the silica precursor and a non ionic surfactant Triton X100 (TX100) and a cationic surfactant Hexadecyltrimethylammonium Bromide (CTAB) as templates. The xerogels were synthesized through 2‐way catalysis using ultrasonic radiations for homogeneous mixing of the precursors and template. The surfactant template was later removed through calcination at 550 °C. It was found out that gels having CTAB as the template had higher surface area (612.08 m²/g) than the gels templated by TX100 (539.6 m²/g). High surface area xerogels were used in adsorption experiments for aqueous solutions of Rhodamine 6G (R6G). UV visible spectroscopy was used to find out the concentrations of dye solutions. The adsorption data of both the types of xerogels was found to follow Freundlich's adsorption model pointing towards the possibility of adsorption of the dye molecules on the heterogeneous surface of the adsorbent.     

Synthesis of molecularly imprinted polymer with 7-chloroethyl-theophylline-immobilized silica gel as template and its molecular recognition function

By reaction of 7-chloroethyl-theophylline with aminopropylsilanized silica gel we synthesized a 7-chloroethyl-theophylline-immobilized silica gel as template molecule and prepared a molecularly imprinted polymer (MIP-Si), which had special recognition sites to 7-chloroethyl-theophylline. A conventional molecularly imprinted polymer (MIP) using 7-chloroethyl-theophylline as template was also prepared for comparison. Binding abilities to 7-chloroethyl-theophylline and its structural analogs revealed that the MIP-Si shows much higher binding speed and much more binding capacity than the MIP does.     

Sulfonamide imprinted polymers using co-functional monomers

Molecular imprinted polymers (MIPs) prepared using combination of acrylamide (ACM) and 4-vinylpyridine (4-Vpy) as co-functional monomers exhibited efficient recognition properties in both organic and aqueous media as HPLC stationary phase. The results indicate that amide and pyridine groups in functional monomers formed strong hydrogen-bonding interaction with the template molecule, and specific recognition sites were created within the polymer matrix during the imprinting process. When sulfamethoxazole (SMO) was used as template, a MIP prepared in a polar organic solvent (acetonitrile) using the combination of ACM and 4-Vpy showed better recognition of template than the polymer prepared in the same solvent using the combination of acidic monomer (methacrylic acid) and basic monomer 4-Vpy. On the contrary, when sulfamethazine (SMZ) was used as template, a MIP prepared using the combination of methacrylic acid (MAA) and 4-Vpy showed better recognition of template than the polymer prepared using the combination of ACM and 4-Vpy. Our results indicate that in organic media the degree of retention of the sample molecules on the imprinted polymers was controlled by the hydrogen-bonding interaction between the sample molecules and the polymer, while in aqueous media it was determined to a considerable extent by hydrophobic interactions. In both media the shape, size and the electronic structure of the template molecule were all-important factors in the recognition process.     

Molecular dynamics simulations of pregelification mixtures for the production of imprinted xerogels

A series of molecular dynamics (MD) simulations of different pregelification mixtures representing intermediate stages of the sol-gel process were set up to gain insight into the molecular imprinting process in xerogels, namely, to assess the template-gel affinity and template self-aggregation. The physical plausibility of the parametrization was checked, confirming the reliability of the simulations. The simulated mixtures differed in the water/methanol ratio (1:3, 5:3, and 5:1) and in the absence/presence of an organic functional group (phenylaminopropyl-) in the silicate species. The simulation results, expressed mainly by the radial distribution functions and respective coordination numbers, showed that the affinity of the template molecule, damascenone (a hydrophobic species), for the gel backbone would not be attained without the tested functional group, phenylaminopropyl-. The affinity, related to the capability to trap the template within the gel network, was derived mostly from the hydrophobic interaction. It was also inferred from MD simulations that lower water contents (methanol-richer mixtures) would facilitate a better dispersion of both the functional group and the template within the final gel, therefore favoring the imprinting process. From the experimental counterparts of the simulated mixtures, a series of imprinted and nonimprinted xerogels were obtained. There was only one xerogel exhibiting the imprinting effect, namely, the one containing the organic group obtained at the lower water/methanol ratio (1:3), in agreement with predictions from the MD simulations. Such congruence demonstrates the ability of MD simulations to provide information regarding the fine aspects of molecular interactions in pregelification mixtures for imprinting.     

Theoretical design and selectivity researches on the enrofloxacin imprinted polymer

In this paper, enrofloxacin (ENRO) was chosen as the template molecule, 4-vinylpyridine (4-Vpy), acrylamide (AM), trifluoromethacrylic acid (TFMAA), and 2-hydroxyethyl methacrylate (HEMA) were selected as the functional monomers, with the following cross-linking agents, ethylene glycol dimethacrylate (EDMA), pentaerythritol triacrylate (PETA), and trimethylolpropane trimethacrylate (TRIM). The stable complex configurations formed by ENRO and four monomers at the molar ratio of 1:1 were calculated using the density functional theory at the B3LYP/6-31G(d,p) level. Their natural bond orbital charges and the action sites were discussed to screen the appropriate functional monomer. The optimal molar ratio of template–monomer complex and the effects of cross-linking agent were investigated. The nature of the imprinting interaction was also researched via the infrared spectrum. The results reveal that the complex formed from ENRO and TFMAA has the strongest hydrogen bond interaction. When the molar ratio is 1:7, the complex has the most stable configuration. Owning to the weakest interaction between EDMA and ENRO, and the strongest interaction between EDMA and TFMAA, EDMA is considered as the suitable cross-linking agent, in comparison with PETA and TRIM for ENRO-MIPs. After the removal of ENRO molecule, the most stable ENRO-TFMAA complex owing to the better binding capacity to ENRO is compared with its structural analogues (ciprofloxacin, sparfloxacin, pefloxacin, ofloxacin, and sarafloxacin). This study provides a reliable theoretical guidance for the preparation of new ENRO-MIPs.     

Spectrofluorimetric determination of tetracycline and anhydrotetracycline in serum and urine.

A spectrofluorimetric method, involving alkaline degradation and formation of a magnesium complex, is described for the determination of tetracycline (TC) and anhydrotetracycline (ATC) in their mixed solution. Tetracycline is degraded and determined in alkaline solution. This treatment of ATC produces almost no fluorescence, but a fluorescent magnesium complex forms at pH 7.5. Several synthetic samples of TC and ATC, with TC:ATC ratios ranging from 50:1 to 1:50, were analysed. The recoveries of TC and ATC are about 71-76 and 61-63% in serum, respectively, and are all about 100% in urine.     

右旋邻氯扁桃酸分子印迹聚合物的制备及结合特性研究

以右旋邻氯扁桃酸为模板分子合成了具有高选择性的分子印迹聚合物作为手性分离材料 .紫外光谱研究说明在聚合开始之前模板分子与功能单体形成了配合物 ,并用Hyperchem软件模拟其分子结构 ,结合能分别为 -1 643 7× 1 0 4 J·mol- 1 和 -4 2 799× 1 0 4 J·mol- 1 .分子印迹聚合物对模板分子的结合量高于其它类似物 ,手性分离因子α达 1 76.Scatchard分析表明分子印迹聚合物在识别右旋邻氯扁桃酸分子过程中存在两类结合位点 ,与配合物模拟结构数目一致     

Molecularly Imprinted Poly-o-phenylenediamine Electrochemical Sensor for Entacapone

We have developed a molecularly imprinted polymer (MIP) electrochemical sensor for entacapone (ETC) based on an electropolymerised polyphenylenediamine (Po-PD) on a glassy carbon electrode (GCE) surface. The direct electropolymerisation of the o-phenylenediamine monomer (o-PD) was carried out with ETC as a template. The steps of electropolymerization process, template removal and binding of the analyte were tested by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using [Fe(CN)₆]³⁻/[Fe(CN)₆]^{4 −} as a redox probe. The operation of the sensor has been investigated by differential pulse voltammetry (DPV). Under optimal experimental conditions, the response of the DPV was linearly proportional to the ETC concentration between 1.0×10⁻⁷ and 5.0×10⁻⁶ M ETC with a limit of detection (LOD) of 5.0×10⁻⁸ M. The developed sensor had excellent selectivity without detectable cross-reactivity for levodopa and carbidopa. The MIP sensor was successfully used to detect ETC in spiked human serum samples.     

Spectrofluorimetric assay of tetracycline and anhydrotetracycline in combination

Spectrofluorimetric methods are described for the assay of tetracycline (TC) and anhydrotetracycline (ATC) in combination, without prior separation. The interference from ATC in the TC assay has been corrected for by forming the aluminium complexes of both drugs and measuring the difference in fluorescence at 475 and 418 nm, with excitation at 393 nm. Similarly, measurement of the fluorescence of the magnesium complexes at 525 and 470 nm (excitation at 440 nm) nullifies TC interference in the ATC assay.     

齐墩果酸分子印迹聚合物预组装体系的分子模拟及聚合物制备

以齐墩果酸(OA)为模板分子,三氟甲基丙烯酸(TFMAA)、α-甲基丙烯酸(MAA)、丙烯酰胺(AM)、4-乙烯基吡啶(4-VP)为功能单体,三氯甲烷、四氢呋喃、乙醇、甲醇和丙酮为溶剂,基于量子化学密度泛函理论(DFT)和ONIOM方法,采用Gaussian09软件模拟计算了模板分子与不同功能单体的印迹聚合物预组装体系的构型,探讨了模板分子与功能单体在不同印迹比例时所形成复合物的成键情况以及反应过程中的结合能,并采用自洽反应场极化连续模型(CPCM)计算了功能单体与模板分子在不同溶剂中的溶剂化能。结果表明,TFMAA与模板分子OA以1:1摩尔比形成复合物的结合能ΔE最高(-70.99kJ·mol~(-1)),结构最稳定,模板分子和功能单体在三氯甲烷中的溶剂化能最小。同时,采用实验方法验证模拟结果,并利用扫描电镜、傅里叶红外光谱仪和静态吸附实验对印迹聚合物的形貌、化学基团和吸附性能等进行表征。结果表明,模拟结果与实验结果完全一致,计算机模拟对分子印迹体系的筛选和机理研究提供了理论依据。     

Silica imprinted materials containing pharmaceuticals as a template: textural aspects

Silica-based materials were prepared by the acid catalyzed sol?Cgel method using different pharmaceuticals as a template. The template molecules investigated were fluoxetine, gentamicin, lidocaine, morphine, nifedipine, paracetamol and tetracycline. The resulting hybrid silicas underwent ultrasound extraction in the presence of several solvents and were characterized by elemental analysis, porosimetry by adsorption/desorption of nitrogen (BET method), small-angle X-ray scattering and X-ray diffraction. Drug extraction was carried out by the combination of solvent and ultra-sound. The textural characteristics of the hybrid xerogels and resulting imprinted materials were shown to be highly dependent on the molecular weight and molecular volume of the drug template. Increasing the molecular weight of the template results in a decrease in the encapsulation content of the resulting material. In the case of paracetamol and fluoxetine, the dimensions of the surface area are not sufficient to guarantee the adsorption of the smaller molecule. Instead, the shape generated through encapsulation and extraction during the production of the imprinted silica dictates the adsorption behavior.     

Influence of Hydrogen Bonds and Nonspecific Interactions on the Spectral and Photophysical Properties of the Excited Singlet States of 4‐Aminophthalimide in Amine Solution

The hydrogen‐bond and nonspecific interaction energies for 4‐aminophthalimide (4‐AP), often used as a probe, in the ground electronic and excited singlet states are determined using ab initio computational methods. It is shown that the 4‐AP molecule can form three relatively strong hydrogen bonds with trimethylamine (TMA) and triethylamine (TEA), which leads to the formation of S₀‐complexes between the solute and solvent molecules. Only two of the hydrogen bonds with the amine group of 4‐AP change significantly their energies upon excitation and deactivation. The theoretical results are necessary to explain the spectral and unusual photophysical properties of 4‐AP in amine solutions.     

含乙烯氧基柔链的苯并菲盘状液晶清亮点的平均场理论研究

我们前期的合成和实验发现, 对于一系列含端烯氧基醚链的苯并菲分子, 它们没有分子间氢键, 其生成的液晶的清亮点的高低与端烯氧基醚链的数目有关. 本工作采用Gay-Berne势模拟液晶分子的双体势, 用量子化学和分子力学相结合的ONIOM(MP2/6-31G*(0.25):UFF)方法优化含端烯氧基醚链的苯并菲分子的单体和双体的构型和能量, 从而获得Gay-Berne势的参数. 在此基础上, 根据平均场理论, 解一个关于序参量和温度的积分方程, 求出液晶的清亮点. 计算结果与实验趋势相同, 可以解释清亮点和分子端烯氧基醚链数目的关系.     

Rapid,simple and selective determination of 2,4-dinitrophenol by molecularly imprinted spin column extraction coupled with fluorescence detection

A rapid, simple and selective method based on molecularly imprinted, spin column extraction coupled with fluorescence detection was successfully established for the determination of 2,4-dinitrophenol in serum samples. The 2,4-dinitrophenol imprinted polymers exhibited highly selective recognition for the template molecule and the maximum adsorption capacity was 138.9 mg/g. The results indicated that when water is used as the loading solution, only 2,4-dinitrophenol could be adsorbed on the spin column without the remaining structural analogs（2-nitrophenol, 4-nitrophenol and phenol）. After eluting with acetonitrile/acetic acid（9/1, v/v）, 2,4-dinitrophenol in serum samples could be determined by using the fluorescence spectrometer, based on the fluorescence enhancement of fluorescein by the template molecule. Under the optimal conditions, the spiked recovery ranged from 95.8% to 103.4% and the detection limit was 1 nmol/L. The results confirmed the reliability and practicality of the protocol and revealed a good perspective of this method for biological sample analysis.