Atrazine transforming polymer prepared by molecular imprinting with post-imprinting process

Molecularly imprinted polymers bearing atrazine transforming activity were prepared by using newly designed templates that are atrazine analogues attached with an allyl or a styryl group via a disulfide bond at the 6-position, methacrylic acid as a functional monomer and styrene/divinylbenzene as crosslinkers. After polymerization, the disulfide bond was reduced to remove the atrazine moiety from the polymer matrix, followed by oxidation of the remaining thiol group to generate sulfonic acid (post-imprinting treatment), so that both a methacrylic acid residue and a sulfonic acid residue existed in an atrazine-imprinted cavity. The polymers indicated the selective binding of triazine herbicides and catalytic activity for methanolysis at the 6-position of atrazine, yielding a low toxic atraton.     

Imprinted Polymeric Film-Based Sensor for the Detection of Dopamine Using Cyclic Voltammetry

The imprinted polymeric film was synthesized on the glass-carbon electrodes dlrectly. The response to the template molecule-dopamine and other molecules with similar structure was measured by cyclic voltammetry. The response of dopamine on imprinted electrode was much higher than that of other molecules,because of the existing of micro-cavities in polymeric rdm fitting with the size and shape of dopamine in the imprinted polymer.Experimental results showed that dopamlne can be enriched by the imprinted film, therefore increasing the sensitivity of the sensor. The imprinted film could also efface the interference of ascorbic acid, indicating that dopamine can be determined with a large excess of ascorbic acid.     

Post-oxidative conversion of thiol residue to sulfonic acid in the binding sites of molecularly imprinted polymers: disulfide based covalent molecular imprinting for basic compounds

An imprinted polymer using a disulfide derivative as a template was treated with NaBH4 to yield the polymer with thiol groups in the binding sites. The thiol groups were then oxidized with H2O2/AcOH to yield the molecularly imprinted polymer with sulfo groups in the binding sites. This site conversion can provide amine-imprinted polymers, in which amine is retained to the imprinted polymer by the strong electrostatic interaction between the amino group and the sulfo group in the binding sites.     

Immobilization of Glycosylated Enzymes on Carbon Electrodes,and its Application in Biosensors

A novel approach was used to immobilize glycosylated enzymes on a glassy carbon electrode (GCE) based on the interaction of boronic acid and carbohydrate moiety within the glycoproteins. 4-Aminomethylphenylboronic acid (4-AMBA) was covalently grafted on a glassy carbon electrode (GCE) by amine cation radical formation in the electrooxidation process of the amino-containing compound. The boronic acid group immobilized in this way could recognize glycoproteins such as glucose oxidase, horseradish peroxidase, dehydrogenase and others. X-ray photoelectron spectroscopy measurement proved the presence of a 4-AMBA monolayer on the GCE. The adsorptions of three kinds of enzymes were investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The activity of the immobilized horseradish peroxidase was also studied.     

Selective adenosine-5'-monophosphate uptake by water-compatible molecularly imprinted polymer

Molecularly imprinted polymers (MIPs) were prepared for adenosine-5′-monophosphate (AMP), a substrate of AMP-activated protein kinase. The template molecule was formed by the vinylphenylboronate diester of adenosine on which 5′-free hydroxide was protected by tert-butyldimethylsilyl group in order to mimic the steric hindrance of the phosphate moiety of AMP. Molecular imprinting was performed by complexing acrylamide and the template in a highly cross-linked polymer. MIPs were tested in batch experiments with aqueous samples of nucleotides and a number of parameters were investigated. The use of tetrabutylammonium hydroxide (TBAH) was necessary to obtain a rebinding of nucleotides on MIP. The adsorption of AMP was optimal in 5 mM ammonium acetate buffer solution pH 9.5 for 30 min, with 30 mM of TBAH. The imprinted polymer was selective for AMP towards others nucleotides or deoxi analogues.     

Analysis of recognition of fructose by imprinted polymers

Binding of fructose to the fructose imprinted polymer (MIP(Frc)) and pinacol imprinted polymer (control) were studied both in batch and a flow through mode. The influence of the cross-linkers ethylene glycol dimethacrylate (EDMA) and trimethylolpropane trimethacrylate (TRIM) on the binding characteristics was analysed. TRIM cross-linked MIPs showed a lower (unspecific) binding for the control polymer (pinacol imprinted) and higher binding of fructose as compared with the EDMA-MIPs. Furthermore interactions of a TRIM cross-linked molecularly imprinted polymer against fructose and its corresponding template were studied using a thermistor. Label-free detection of fructose was realised in the range of 0.5-10mM. The difference in enthalpy changes between specific binding of fructose to boronic acid moieties of the MIP and non-specific binding to the matrix leads to an 18-fold higher apparent imprinting factor than batch binding studies. Cross-reactivity studies using MIP sensor indicate that the interaction of fructose to MIP generates higher signal than disaccharides. The studies described in this paper demonstrate the potential of direct characterisation of molecular binding events.     

Substitution and condensation reactions with poly(anilineboronic acid): reactivity and characterization of thin films

Poly(anilineboronic acid) thin films are treated under various conditions to achieve substitution or condensation reactions involving the boronic acid moiety. These reactions are studied with polarization modulated infrared reflection absorption spectroscopy, cyclic voltammetry, and UV-vis spectroscopy. The results suggest the single-step formation of substituted polyanilines, such as poly(hydroxyaniline), halogenated polyanilines, and mercury chloride-substituted polyaniline. A condensation reaction of poly(anilineboronic acid) with cis-diol compounds in aqueous solution, as well as with phenylenebisboronic acid and salycilamide in THF, indicates the formation of boronic esters. The latter reactions appear to be a good entry point for the formation of complex or supramolecular polymer structures.     

A new fluorescein derivative bearing a boronic acid group as a fluorescent chemosensor for fluoride ion

A new fluorescein derivative 1 bearing a boronic acid group was investigated as a fluorescent chemosensor for F-. An off-on type fluorescence enhancement was observed by the blocking of the photoinduced electron transfer mechanism, which was induced by the interaction between fluoride and boronic acid moiety.     

Diols and anions can control the formation of an exciplex between a pyridinium boronic acid with an aryl group connected via a propylene linker

The exciplex formation between a pyridinium boronic acid and phenyl group connected via a propylene linker can be monitored using fluorescence. Addition of pinacol affords a cyclic boronate ester with enhanced Lewis acidity that increases the strength of its cation-π stacking interaction causing a four-fold fluorescence enhancement.     

Chiral Brønsted acid catalyzed enantioselective Mannich-type reaction

Mannich-type reaction of ketene silyl acetals with aldimines proceeded catalytically by means of a phosphoric acid diester, derived from (R)-BINOL, as a chiral Br?nsted acid to afford beta-amino esters with good diastereoselectivity in favor of the syn isomer and high enantioselectivity (up to 96% ee). The highest enantioselectivity was achieved by the phosphoric acid diester bearing 4-nitrophenyl groups on the 3,3'-positions of BINOL. The N-2-hydroxyphenyl group of aldimine was found to be essential for the present Mannich-type reaction. In combination with these experimental investigations, two possible monocoordination and dicoordination pathways were explored using density functional theory calculations (BHandHLYP/6-31G*). The present reaction proceeds via a dicoordination pathway through the zwitterionic and nine-membered cyclic transition state (TS) consisting of the aldimine and the phosphoric acid. The re-facial selectivity was also well-rationalized theoretically. The nine-membered cyclic structure and aromatic stacking interaction between the 4-nitrophenyl group and N-aryl group would fix the geometry of aldimine on the transition state, and the si-facial attacking TS is less favored by the steric hindrance of the 3,3'-aryl substituents.     

Interference of ascorbic acid in the sensitive detection of dopamine by a nonoxidative sensing approach

The electrochemistry of a poly(anilineboronic acid)/carbon nanotube composite was studied in the presence of dopamine and ascorbic acid. To understand the binding affinity of dopamine and ascorbic acid to the boronic acid functional groups in the composite, the association constants between the diol groups in dopamine and ascorbic acid and the boronic acid were experimentally determined using a fluorescence-based binding assay. The results demonstrate that ascorbic acid could severely interfere with the detection of dopamine in nonoxidative boronic acid-binding approaches: Ascorbic acid was able to electrocatalytically reduce the fully oxidized polyaniline backbone during the electrochemical oxidation process; similarly to dopamine, ascorbic acid was also able to bind to the boronic acid groups through its planar diol group even though the binding affinity is much lower. The examination of the dopamine transduction mechanism and ascorbic acid interference mechanism in this nonoxidative approach will benefit the design of future boronic acid-based sensors.     

Molecularly imprinted polystyrene–titania hybrids with both ionic and π–π interactions: a case study with pyrenebutyric acid

We present hybrid films consisting of a composite prepared from polystyrene (PS) and titanium dioxide (titania; TiO₂) and molecularly imprinted with 1-pyrenebutyric acid (PBA). The interaction of PBA with the polymer is shown to occur via binding of the carboxylic group to TiO₂ and hydrophobic interaction of the pyrene moiety with the PS network. We investigated the effects of the PS fraction on morphology, imprinting properties, and guest binding. The template could be completely removed by incubating the films in an acetonitrile solution of pyrene, which is due to the stronger π–π interaction between PBA and pyrene than the interaction between PBA and its binding site. A guest binding study with pyrene, 1-aminopyrene, pyrenemethanol, and anthracene-9-carboxylic acid showed that the hybrid films possessed selectivity and much higher binding capacity for PBA. This study demonstrates the first case of clear PS-assisted imprinting, where the π–π interaction of the template with a linear (non-crosslinked) polymer creates selective binding sites and enhances the binding capacity. This is a driving force for guest binding in addition to the interaction of the template/analyte with TiO₂. All molecularly imprinted films displayed better binding, repeatability and reversibility compared to the respective non-imprinted films.

Poly(glyceryl glycerol): A multi‐functional hydrophilic polymer for labeling with boronic acids

The synthesis of poly(glyceryl glycerol) (PGG), a polymer featuring a polyethylene oxide backbone and 1,2‐diol groups in every repeating unit, is presented. PGG was prepared by monomer‐activated ring‐opening polymerization of (dl ?1,2‐isopropylidene glyceryl) glycidyl ether, introducing a functional azido‐ or bromo‐head group to each chain. The 1,2‐diol groups, which were released by acidic deprotection, readily reacted with boronic acid derivatives, enabling the attachment of functional moieties under mild aqueous conditions. PGG was conjugated to poly(l ‐lactide) (PLLA) via azide‐alkyne cycloaddition and the resulting copolymer assembled into nanoparticles of 70 nm diameter in aqueous solution. Labeling of the PGG–PLLA particles was achieved by simple mixing with a boronic acid‐functional fluorophore. The labeling efficiency was determined by fluorescence spectroscopy to be 85.5% for boronic acid‐functional rhodamine B compared with 0.2% for plain rhodamine B. The strong interaction of PGG with boronic acids is ascribed to its polyol structure. This study demonstrates the usefulness and versatility of PGG as a hydrophilic polymer for possible biomedical applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1822–1830     

Synthesis and cationic ring-opening polymerization of mono- and bifunctional spiro orthoesters containing ester groups and depolymerization of the obtained polymers: An approach to chemical recycling for polyesters as a model system

A spiro orthoester having an ester moiety, 2-acetoxymethyl-1,4,6-trioxaspiro[4.6]undecane (4) was synthesized, and its cationic polymerization and depolymerization of the obtained polymer (5) were carried out. The monomer 4 underwent cationic polymerization with a cationic catalyst to afford the corresponding poly(cyclic orthoester) 5. The obtained polymer 5 could be depolymerized with a cationic catalyst to regenerate the monomer 4 in an excellent yield. Further, bifunctional spiro orthoesters (6, 8, 9) having diester moieties were synthesized from terephthalic acid, succinic acid, and 1,4-cyclohexanedicarboxylic acid, and their acid-catalyzed reversible crosslinking–decrosslinking was examined. The bifunctional monomer 6 derived from terephthalic acid underwent cationic crosslinking to afford the corresponding network polymer (7), which could be also depolymerized to regenerate the original bifunctional monomer 6. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2551–2558, 1999     

多巴胺有序介孔硅表面分子印迹传感器的研制

以多巴胺(DA)为模板,氨基修饰的介孔硅为载体,制得对多巴胺具有特异选择性的表面分子印迹聚合物(MIP)。将所得的MIP制成碳糊电极,用循环伏安法对多巴胺进行检测。在优化实验条件下,传感器的氧化峰电流与多巴胺浓度在1.0×10-7～2.0×10-6mol/L和2.0×10-6～1.0×10-4mol/L范围内呈良好的线性关系,相关系数分别为0.992 5和0.996 9,检出限为1.3×10-9mol/L。该传感器对DA具有较高的灵敏度和选择性,将其用于实际样品检测,结果满意。     

Ultrasensitive fluorescent responses of water-soluble, zwitterionic, boronic acid-bearing, regioregular head-to-tail polythiophene to biological species

Water-soluble regioregular head-to-tail zwitterionic fluorescent conjugated boronic acid-bearing polythiophene (polymer 2) was prepared through a postpolymerization quaternization of a pyridine group of 3-pyridineboronic acid with bromide groups of regioregular head-to-tail poly(3-bromohexylthiophene) (polymer 1). Titration of monosaccharides, lactose, ascorbic acid, or dopamine with 0.1 M phosphate buffer (pH 7.4), containing 4.0 microM of polymer 2, results in significant concentration-dependent quenching of the polymer fluorescence. The polymer displays an optimum response to the biological species at pH 7.0. The binding constants of polymer 2 with mannose, fructose, glucose, galactose, vitamin C, dopamine, and lactose are 3.33 x 10(4), 1.13 x 10(5), 1.23 x 10(5), 1.69 x 10(5), 3.17 x 10(5), 3.27 x 10(5), and 4.60 x 10(5), respectively.     

Effective separation of dopamine from bananas on 2-(3,4-dimethoxyphenyl)ethylamine imprinted polymer

A 2-(3,4-dimethoxyphenyl)ethylamine imprinted polymer (MIP(pt) ) was prepared via the precipitation polymerization together with a nonimprinted polymer (NIP). The morphology of particles was investigated by scanning electron microscopy and the specific surface areas were estimated by methylene blue adsorption (60.5 ± 3.5 and 36.9 ± 1.2 m(2)/g for MIP(pt) and NIP, respectively). The binding experiments were performed to determine the binding capacity of MIP(pt)/NIP particles toward dopamine. Next, the effects of solvents on loading, washing, and eluting steps were examined on solid-phase extraction (SPE). Methanol-water 85:15 v/v (loading step), methanol (washing step), and 0.04 M aqueous ammonium acetate-methanol 30:70 v/v (eluting step) were selected as the most effective systems. Described SPE protocol was successfully applied for separation of dopamine on 2-(3,4-dimethoxyphenyl)ethylamine imprinted particles. Finally, the molecularly imprinted polymer was used for determination of dopamine in spiked banana extract. The total recovery of dopamine from MIP(pt) was equal to 88.5 ± 4.6%, but from NIP was only 12.8 ± 2.3%. The developed material and method were demonstrated to be applicable for the separation of dopamine from bananas. The commercial sorbent C18 was not suitable to such application.     

电子束辐射聚合制备槲皮素-镍(Ⅱ)金属配位分子印迹聚合物及其识别性能研究

以电子束为辐照射线源,采用辐射聚合法成功制备了槲皮素-Ni(Ⅱ)金属配位分子印迹聚合物.通过紫外光谱研究了槲皮素与Ni(Ⅱ)之间的配位结构、配位作用方式及配位比,并按照1∶2的比例形成稳定配合物,同时也验证了槲皮素、Ni(Ⅱ)及功能单体甲基丙烯酸三者发生了金属配位印迹作用.利用红外光谱对产物的结构进行了表征.透射电镜、扫描电镜、吸附动力学实验分别考察辐射剂量对聚合物的微观形貌、吸附动力学性能的影响,结果表明辐射剂量对印迹聚合物的吸附性能有显著影响.同时选择性吸附实验结果显示该印迹聚合物对槲皮素-Ni(Ⅱ)配合物表现出明显的吸附选择性和特异性,最大结合量可达82.22μmol/g.对黄芩素和柚皮素的吸附选择性较差,分离因子分别为3.915和5.443.     

Molecularly imprinted polystyrene–titania hybrids with both ionic and π–π interactions: a case study with pyrenebutyric acid

We present hybrid films consisting of a composite prepared from polystyrene (PS) and titanium dioxide (titania; TiO₂) and molecularly imprinted with 1-pyrenebutyric acid (PBA). The interaction of PBA with the polymer is shown to occur via binding of the carboxylic group to TiO₂ and hydrophobic interaction of the pyrene moiety with the PS network. We investigated the effects of the PS fraction on morphology, imprinting properties, and guest binding. The template could be completely removed by incubating the films in an acetonitrile solution of pyrene, which is due to the stronger π–π interaction between PBA and pyrene than the interaction between PBA and its binding site. A guest binding study with pyrene, 1-aminopyrene, pyrenemethanol, and anthracene-9-carboxylic acid showed that the hybrid films possessed selectivity and much higher binding capacity for PBA. This study demonstrates the first case of clear PS-assisted imprinting, where the π–π interaction of the template with a linear (non-crosslinked) polymer creates selective binding sites and enhances the binding capacity. This is a driving force for guest binding in addition to the interaction of the template/analyte with TiO₂. All molecularly imprinted films displayed better binding, repeatability and reversibility compared to the respective non-imprinted films.

Illustration of the fabricated polystyrene/titania hybrids imprinted with 1-pyrenebutyric acid providing the interaction between the organic and inorganic components through the pyrene and carboxylic moieties

     

Optimization of serotonin imprinted polymers and recognition study from platelet rich plasma

Molecularly imprinted polymers using serotonin as the template molecule was prepared for selective recognition from platelet rich plasma by non-covalent imprinting approach. Four different monomers (methacrylic acid, acrylamide, 4-vinylpyridine and 2-acrylamido-2-methylpropane sulfonic acid) and acetonitrile and DMSO as porogen were investigated for the first time by bulk polymerization. The molecularly imprinted polymer which was prepared by acrylamide/methacrylic acid had the largest imprinting factor for serotonin. The affinity and specificity of these polymers were evaluated by equilibrium binding experiments. The effect of polarity of the solvents was examined by polymers binding capacity and imprinting factor. According to the Scatchard analysis the K(d) and Q(max) values were calculated as 1.95 micromoll(-1) and 19.129 micromolg(-1), respectively. The polymer was tested to evaluate serotonin from platelet rich plasma and 70% serotonin recovery was found.