双模板分子印迹聚合物在奶粉检验中的应用研究

采用本体聚合法制备三聚氰胺(MEL)与双氰胺(DCD)双模板分子印迹聚合物(MEL/DCD-MIPs),将其作为固相萃取介质,实现了奶粉中MEL与DCD富集与纯化,建立了奶粉中两种物质同时检测的方法。通过热力学、选择性和动态结合试验表明,与单模板分子印迹聚合物相比,双模板分子印迹聚合物由于双模板-功能单体分子间的多位点协同作用而有更好的印迹效应,对MEL和DCD结合能力高于结构类似物三聚氰酸(CYA)。固相萃取试验显示,MEL/DCD-MIPs可以从市售奶粉中选择性地分离、富集MEL与DCD,对MEL与DCD的加样回收率分别为93.1%~100.1%和75.7%~82.5%,RSD均小于5.2%。所制得的MEL/DCD-MIPs可应用于奶粉等食品中氰胺类物质的检测。     

沉淀聚合法制备吲哚乙酸印迹聚合物及其吸附性能研究

以吲哚乙酸(IAA)为模板分子、乙腈为致孔剂,采用沉淀聚合法制备了其分子印迹聚合物,通过静态吸附实验研究了致孔剂乙腈的用量及4-乙烯基吡啶(4-VP)和丙烯酰胺(AA)两种不同性质的功能单体(M)对印迹聚合物吸附性能的影响。结果表明,以4-VP为M,乙腈的加入量分别为20、25、37.5和50 m L时,制备的印迹聚合物P1~P4均具有良好的分散性,且聚合物P4对IAA具有最显著的印迹效应(印迹因子IF=2.92);而在同样条件下以AA为M的印迹聚合物的印迹效应较小(IF=1.73)。选择性实验表明,聚合物P4能够从吲哚羧酸同系物中选择性结合IAA。Scatchard分析表明,聚合物P4对IAA表现出两类结合位点,其高亲和力与低亲和力结合位点的平衡离解常数分别为Kd1=0.798 mmol/L和Kd2=7.76 mmol/L,对应的最大结合量分别为21.0和90.7μmol/g。     

Synthesis of a Temperature-Sensitive Matrine-Imprinted Polymer and Its Potential Application for the Selective Extraction of Matrine from Radix Sophorae Tonkinensis

A temperature-sensitive matrine-imprinted polymer was prepared in chloroform by free-radical cross-linking copolymerization of methacrylic acid at 60 °C in the presence of ethylene glycol dimethacrylate as the cross-linker, N-isopropyl acrylamide as the temperature-responsive monomer and matrine as the template molecule. Binding experiments and Scatchard analyses revealed that two classes of binding sites were formed on molecular imprinted polymer (MIP) at 50 °C. Additionally, the thermoresponsive MIP was tested for its application as a sorbent material for the selective separation of matrine from Chinese medicinal plant radix Sophorae tonkinensis. It was shown that the thermoresponsive MIP displayed different efficiency in clean-up and enrichments using the SPE protocol at different temperatures.     

生物大分子印迹聚合膜的表征及电化学应用

使用扫描电子显微镜(SEM)、红外图谱(IR)、循环伏安(CV)、差示脉冲循环伏安(DPV)对血红蛋白聚合物膜修饰电极进行了表征。DPV测试表明血红蛋白的浓度和峰电流分别在低浓度和高浓度下均有良好的线性关系,低浓度下满足线性回归方程ip(μA)=13.05-3.58C(μM),相关系数R为-0.9960。检出限为2.7×10-9M,线性范围8.0×10-9~7.1×10-7M;高浓度下满足线性回归方程Ip(μA)=10.56-0.1001C(μM),相关系数R为-0.9957。检出限为5.7×10-7M,线性范围1.7×10-6~1.4×10-5M。可用于构建生物分子印迹的电化学传感器。     

吲哚-3-乙酸分子印迹聚合物的合成及吸附性能分析

以吲哚-3-乙酸(indole-3-acetic acid,IAA)为模板、甲基丙烯酸为功能单体、乙腈为致孔剂,采用本体聚合法合成了对IAA有特异性识别的吲哚-3-乙酸分子印迹聚合物(IAA-MIP)。红外光谱分析表明,IAA是以氢键形式结合在聚合物的空腔中。等温吸附线及Scatchard分析表明,洗脱模板后的IAA-MIP结合IAA的能力比空白印迹聚合物(NIP)强,且有2种结合方式,其解离常数分别为KD1=1.04×10-6 mol·L-1和KD2=9.23×10-6 mol·L-1,最大表观结合位点分别为Bmax1=0.10μmol·g-1和Bmax2=0.28μmol·g-1。对植物样品的固相萃取实验表明,洗脱模板后的IAA-MIP对IAA具有较强的特异性吸附能力。     

Synthesis and Characterization of Molecularly Imprinted Polymer Membrane for the Removal of 2,4-Dinitrophenol

Molecularly imprinted polymers (MIPs) were prepared by bulk polymerization in acetonitrile using 2,4-dinitrophenol, acrylamide, ethylene glycol dimethacrylate, and benzoyl peroxide, as the template, functional monomer, cross-linker, and initiator, respectively. The MIP membrane was prepared by hybridization of MIP particles with cellulose acetate (CA) and polystyrene (PS) after being ground and sieved. The prepared MIP membrane was characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. The parameters studied for the removal of 2,4-dinitrophenol included the effect of pH, sorption kinetics, and the selectivity of the MIP membrane. Maximum sorption of 2,4-nitrophenol by the fabricated CA membrane with MIP (CA-MIP) and the PS membrane with MIP (PS-MIP) was observed at pH 7.0 and pH 5.0, respectively. The sorption of 2,4-dinitrophenol by CA-MIP and PS-MIP followed a pseudo–second-order kinetic model. For a selectivity study, 2,4-dichlorophenol, 3-chlorophenol, and phenol were selected as potential interferences. The sorption capability of CA-MIP and PS-MIP towards 2,4-dinitrophenol was observed to be higher than that of 2,4-dichlorophenol, 3-chlorophenol, or phenol.     

A Zipper‐Like On/Off‐Switchable Molecularly Imprinted Polymer

A zipper‐like on/off‐switchable molecularly imprinted polymer is reported. This unique imprinted polymer was composed of template‐imprinted polymeric networks that incorporate zipper‐like interactions between poly(acrylamide) (PAAm) and poly(2‐acrylamide‐2‐methyl propanesulfonic acid) (PAMPS). This polymer showed marginal recognition ability towards the imprint species under low temperature conditions, due to the interpolymer interaction between PAAm and PAMPS, which inhibited access to the imprinted networks. In contrast, at relatively high temperatures (such as 40 °C), the polymer demonstrated significant molecular recognition ability towards the imprint species resulting from the dissociation of the interpolymer complexes of PAAm and PAMPS, which enabled access to the imprint networks. Unlike previously reported PNIPAm‐based imprinted polymers, which demonstrate alterable molecular recognition simply because of the thermosensitive hydrophilicity/hydrophobicity of PNIPAm, this polymer employed a zipper‐like supramolecular architecture between PAAm and PAMPS, thereby enabling switchable molecular recognition.     

The influence of polymer morphology on the performance of molecularly imprinted polymers

This is the first in-depth study examining the effect of morphology on the performance of 2-aminopyridine (2-apy) imprinted polymers. A series of polymers were prepared by varying the amount of crosslinking monomer (EGDMA) whilst the other polymer components remained constant. Physical characterisation was carried out using conventional techniques, such as nitrogen sorption porosimetry and solvent swelling studies. The use of a novel thermal desorption GC-MS technique suggested higher levels of polymer degradation with prolonged exposure to elevated temperatures for those polymers formed with lower amounts of EGDMA. The thermal desorption GC-MS profiles obtained correlated with the physical characteristics of the polymers, where higher levels of polymer bleed was found to occur with larger average pore diameters. Polymer physical characteristics were also found to correlate with the binding parameters (number of binding sites and polymer-template association energy) obtained from the Langmuir-Freundlich Isotherm (L-FI) and affinity distribution spectra (AD). The flexibility of the polymers formed from lower amounts of EGDMA combined the swelling effect of the solvents on the polymers resulted in an increase in affinity, which was both specific and non-specific in nature.     

β-Cyclodextrin Based Molecularly Imprinted Solid Phase Extraction for Class Selective Extraction of Priority Phenols in Water Samples

Molecular imprinted polymer (MIP MAA-β-CD) with 2,4-dichlorophenol (2,4-DCP) and methacrylic acid functionalized β-cyclodextrin (MAA-β-CD) as the template molecule and the functional monomer, respectively, was prepared and used in molecular imprinted-solid phase extraction (MISPE) for the extraction of phenols (2,4-dichlorophenol, 2-chlorophenol, 4-chloro-3-methylphenol, 4-chlorophenol, 2,4,6-trichlorophenol, and 2-nitrophenol) from water samples. The MISPE method was optimized prior to the determination using gas chromatography coupled with a flame ionization detector (GC-FID). Under the optimized conditions, the MIP MAA-β-CD sorbent showed good linearity (0.01-12 mgL^?1), low limits of detection (0.14-0.75 µgL^?1), and good repeatability (RSD 2.3-3.6%, n = 3). Good recoveries were obtained in the range of 97-115% for tap water and between 88-103% for river water. The developed MIP MAA-β-CD SPE was then compared with other adsorbents. The unique properties of β-CD and presence of imprinted cavities explains the higher extraction recoveries obtained for phenols when using MIP MAA-β-CD SPE.     

Design of molecularly imprinted polymer grafts with embedded gold nanoparticles through the interfacial chemistry of aryl diazonium salts

A novel strategy is described for the preparation of highly sensitive molecularly imprinted (MIPs) sensors for dopamine. It combines mercaptobenzene diazonium salt as a coupling agent for immobilizing gold nanoparticles to gold electrodes and benzoyl benzene diazonium salt as photoinitiator of radical polymerization at the said gold nanoparticle-decorated gold electrodes. The MIP films were prepared by surface-initiated photopolymerization (SIPP) of methacrylic acid (MAA) as functional monomer (F) for dopamine (DA) the template molecule (T), and ethylene glycol dimethacrylate (EGDMA), the crosslinker (C). Dimethylaniline was employed as a hydrogen donor. The specificity and selectivity were demonstrated by square wave voltammetry (SWV). The detection limit was 0.35 nmol L^-1 (0.054 ng mL⁻¹). The sensor layers are stable and adherent to the surface through aryl layers. The originality and advantage of the process lie in the use of aryl diazonium salt as coupling agents for anchroring nanoparticles and MIP layers to the electrode surface in a simple and efficient way which ensures high sensing performance together with good surface-MIP adhesion. The same strategy can be extended to a broad range of templates.