Composite Microfiltration Membranes Imprinted with cAMP

Composite microfiltration membranes covered with a thin layer of molecularly imprinted polymer (MIP) selective to adenosine 3′:5′‐cyclic monophosphate (cAMP) were obtained and their separation properties were studied. MIP layers were prepared using photoinitiated copolymerization of dimethylaminoethyl methacrylate (DMAEM) as a functional monomer and trimethylopropane trimethacrylate (TRIM) as a crosslinker in the presence of cAMP as template in ethanol/water mixture. Blank membranes were prepared under the same conditions, but without cAMP. It was found out that pH of aqueous solution of the template has an effect on the binding of cAMP with MIP membranes. It was concluded that the ability of MIP membranes to bind cAMP is a result of both ionic interactions between charged dimethylamino groups of polymer matrix and the phosphorous residue of cAMP molecule and the specific shape of recognizing sites. These sites are complementary to cAMP in terms of three dimensional shape as well as correct position of functional groups involved in the template binding. This paper shows that the binding capability of MIP membranes can be adjusted by varying the values of degree of modification (DM). Atomic Force Microscopy (AFM) and Scanning Force Microscopy (SEM) were used to visualise surfaces and cross sections of membranes to gain better understanding in the analysis of MIP layer deposited on membranes.     

Molecularly Imprinted Membranes with Affinity Properties for Folic Acid

The extraction of folic acid from aqueous solutions was proposed through a novel procedure based on the membrane separation process using the approach of molecular imprinting. Molecularly imprinted membranes were prepared via the phase inversion technique using poly(acrylonitrile-co-acrylamide) copolymer as the membrane material and folic acid as the template molecule. Poly(acrylonitrile)-based membranes were also prepared as the reference material. Polymer composition, membrane preparation method, and the pH used in the binding experiments were the parameters which mostly influenced the recognition properties of the imprinted membranes. In particular, the solvent evaporation method allowed to obtain poly(acrylonitrile-co-acrylamide) imprinted membranes which at pH 5.0 showed a specific binding capacity of 5.3 µmol/g_memb. Corresponding blank membranes (prepared in absence of the template molecule), only showed a poor non-specific binding of 1.0 µmol/g_memb. Polyacrylonitrile-based membranes showed lower folic acid retention (1.5 µmol/g_memb. when prepared in the presence of the template and 0.9 µmol/g_memb. when prepared in the absence of the template).     

Imprinted β‐cyclodextrin polymers using naringin as template

The objective of this study was to identify a kind of molecular imprinting polymer (MIP) which was suitable for recognizing naringin (NG) in aqueous medium. Based on two crosslinkers (hexamethylene diisocyanate and epichlorohydrin) and two polymerization methods (solution polymerization and emulsion polymerization), four non‐covalent naringin‐β‐cyclodextrine (NG‐β‐CD) imprinted polymers were prepared by using β‐CD as a functional monomer and NG as a template molecule. The binding property and selectivity were evaluated by equilibrium binding experiments. These demonstrated that all the sites in the MIPs show good selective binding ability for NG from naringin dihydrochalcone, a structurally similar molecule. Of the four MIPs, rod‐like 3# MIP which was prepared by emulsion polymerization using hexamethylene diisocyanate as crosslinker exhibited the highest selectivity, its imprinting factor α being 1.53. Scatchard analysis of 3# MIP suggests that there are two classes of binding sites during the MIP's recognition of NG. Additionally, the 3# MIP could be used at least five times without any loss in sorption capacity. Copyright © 2011 Society of Chemical Industry     

Rationally Designing Molecularly Imprinted Polymer Toward a High Specific Recognition by Using a Stoichiometric Self-Assembly

This article presents an original work aimed at rationally designing a molecularly imprinted polymer capable of a high specific recognition. Assembling with Bisphenol A as template and acrylamide as functional monomer, the imprinted polymer was prepared. The results indicate that the use of stoichiometric self-assembly plays an obvious role on significantly increasing the specificity of prepared material, so as to better discriminate the template from its analogue. A higher or lower extent of molecular self-assembly would result in a dramatic decrease in this specificity. Related information indicates that this, logically, can be a result of the increasing match between binding sites and the template, which makes the polymer capable of specifically recognizing the imprint species.     

Supercritical CO2-assisted preparation of a PMMA composite membrane for bisphenol A recognition in aqueous environment

This work reports a novel strategy to prepare affinity composite membranes using supercritical fluid technology. By blending molecularly imprinted polymeric particles with PMMA, a porous hybrid structure with affinity to the template molecule, bisphenol A, was prepared using a supercritical carbon dioxide (scCO₂)-assisted method. Membranes were characterized in terms of morphology, mechanical performance and transport properties. The ability of the polymers and hybrid membranes to adsorb bisphenol A was tested in aqueous solutions and fitted to a linearized Langmuir equation, showing that adsorption takes place at homogeneous affinity binding sites within the imprinted surface. Filtration experiments showed that the imprinted hybrid membrane was able to adsorb higher amounts of template even in non-equilibrium dynamic binding conditions. The hybridization of the PMMA membrane herein reported conveys two important improvements over neat PMMA membrane: it introduced molecular affinity towards the template molecule and significantly increased the permeability of the porous structures, which are key parameters in processes that involve membranes. This technique could expand the applications of polymeric beads powders and enhance the efficiency of the membrane's transport properties. Our work presents a new method to confer affinity to a porous structure by immobilization of imprinted polymers, combining polymer synthesis and membrane formation using supercritical fluid technology.     

Preparation and application of Norfloxacin‐MIP/polysulfone blending molecular imprinted polymer membrane

Norfloxacin‐molecular imprinted polymer was prepared by bulk polymerization with Norfloxacin (NFXC) as template molecule, Methacrylic acid (MAA) as functional monomer and Trimethylolpropane Trimethacrylate (TRIM) as cross linking agent. And the imprinted polymer membranes of polysulfone‐matrix were also prepared by blending method. The structures of Norfloxacin‐molecular imprinted polymer were measured and confirmed by spectra of FTIR and TEM, respectively. Although the combination characteristic and mechanism of this molecular recognition membrane were studied by scan electro‐microscope (SEM) and combinative equation experiment, the results showed that the molecular recognition membrane represented high selectivity for Norfloxacin. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Computer simulation and preparation of molecularly imprinted polymer membranes with chlorogenic acid as template

A computational approach was developed for screening functional monomers for rational design of molecularly imprinted polymer (MIP) membranes. It was based on a comparison of the binding energy of complexes between a template and various functional monomers. According to the results of theoretical calculations, MIP membranes with chlorogenic acid as a template were prepared with a UV irradiation polymerization method, using 4‐vinylpyridine as a functional monomer and N,N′‐methylenebisacrylamide as a crosslinker, with poly(vinylidene fluoride) microfiltration membranes as the support. Membranes covered with a thin layer of imprinted polymer selective to chlorogenic acid were then obtained and tested using the equilibrium‐adsorption method. The high affinity of these synthetic membranes to chlorogenic acid, together with their straightforward and inexpensive preparation, provides a good basis for the development of applications of imprinted polymers in separation processes such as solid‐phase extraction. Copyright © 2011 Society of Chemical Industry     

以乙烯基吡咯烷酮为功能单体的金属配合印迹聚合物的制备及水相识别

Using nickel（II） acetate.-2,2＇-dipyridyl complex as template and N-vinyl-2-pyrrolidone （NVP） as coordinate functional monomer,.a new kind of metal-compiexing template molecularly impnnted polymer （MIP） was prepared..The results of equilibri.um binding experiments in. aqueous solution showed that the MIP had higher＇binding capacity for nickel（ II ）-2,2＇-dipyridyl than the non-imprinted polymer with the same chemical composition. Theinfluences of metal ions and pHof solution on the recognition performance of MIP were investigated. The bindingcharacteristics of MIP were evaluated by the Scatchard analysis with one-site and two-site binding equations, respectively. The results on substrate selectivity of imprinted polymer revealed that MIP had better binding affinityfor template among thetested compounds.     

Rationally Designing Molecularly Imprinted Polymers Toward a Highly Specific Recognition by Using a Stoichiometric Molecular Self-assembly

This article presents work on designing a highly specific imprinted polymer for molecular recognition. Based on a stoichiometric molecular self-assembly, the imprinted material was prepared using adenine as the template and methacrylic acid as the functional monomer. The result indicates that the stoichiometric molecular self-assembly plays a positive role in increasing the specificity of prepared materials, so as to adsorb more for the template but less for its analogue. Furthermore, the results indicate that higher or lower extents of self-assembly cause a dramatic decrease in the specificity. Related information indicates that these changes can be an increase in the match of template and the binding framework, which thereby makes the polymer capable of specifically recognizing the imprint species.     

Preparation of molecularly imprinted CS membrane for recognizing naringin in aqueous media

A molecularly imprinted membrane (MIM) was prepared in aqueous media using chitosan (CS) as a functional polymer, naringin (NG) as a template molecule by phase-inversion technique. The morphologies of the MIM before and after modification with the porogen (PEG) were observed by SEM. The imprinted membrane showed an excellent performance when sulfuric acid was used as a cross-linking agent at the mass ratio of CS:NG = 15:1. The FT–IR spectra confirmed that the formation of hydrogen bond between functional polymer and template molecules. The NG–CS MIM was used to separate NG from neohesperidin/NG in the aqueous media, and the highest permeation percentage was 11.16% for 8 h.     

Molecularly imprinted polymers via living radical polymerization: Relating increased structural homogeneity to improved template binding parameters

This work examined imprinted polymer networks prepared via controlled/living radical polymerization (LRP) and conventional radical polymerization (CRP) on chain growth, network formation, and efficiency of producing molecularly imprinted, macromolecular memory sites for the template molecule, diclofenac sodium. LRP extended the reaction-controlled regime of the polymerization reaction and formed more homogeneous polymer chains and networks with smaller mesh sizes. In addition, LRP negated the effect of the template on polymer chain growth resulting in polymers with a more consistent PDI independent of template concentration in the pre-polymerization solution. Improved network homogeneity within imprinted poly(HEMA-co-DEAEM-co-PEG200DMA) networks prepared via LRP resulted in a 38% increase in template binding affinity and 43% increase in the template binding over imprinted networks prepared via CRP and a 97% increase in affinity and 130% increase in capacity over non-imprinted networks prepared by LRP. By varying certain parameters, it was possible to create imprinted networks with even higher template binding affinities (155% over non-imprinted) and capacities (261% over non-imprinted). This work is the first to conclusively demonstrate that the observed improvement in binding parameters in weakly crosslinked, imprinted polymer networks could be explained by the more uniform molecular weight evolution associated with the LRP mechanism and the longer lifetime of an active polymer chain relative to the total polymerization time, which allowed for the formation of a more homogenous imprinted polymer network.     

Thermodynamic and Kinetic Considerations on the Specific Adsorption and Molecular Recognition by Molecularly Imprinted Polymer

This article presents an original work on thermodynamically and kinetically interpreting the specific adsorption and recognition by molecularly imprinted polymer. The imprinted polymer was prepared with Bisphenol A (BPA) dimethacrylate as template monomer. The results indicate that the prepared polymer can well discriminate the template from its analogue, so as to adsorb more for BPA and less for DHBP. Kinetic analysis indicates that this specific adsorption, in nature, can be a result of preferential promotion. The imprint leads to a larger adsorption-rate in the template than in its analogue. Thermodynamic study also implies that the molecular induction of imprint toward BPA is larger than toward DHBP, which thus makes the polymer capable of specifically allowing the template to bind.     

Nanopore Molecularly Imprinted Polymer Membranes for Environmental Usage: Selective Separation of 2,4-Dichlorophenoxyacetic Acid as a Toxic Herbicide from Water

Nanopore molecularly imprinted polymers and membranes for selective separation of 2,4-dichlorophennoxyacetic acid were prepared using 2,4-dichlorophennoxyacetic acid as a template molecule, methacrylic acid as a functional monomer and trimethylolpropane trimethacrylate as a cross linker. Recognition properties of molecularly imprinted membranes were evaluated by performing binding experiments with analog phenoxyacetic acid. Flux, permeability, and permselectivity of the membranes as well as their properties were studied. Molecularly imprinted membrane-2 showed the equilibrium binding capacity of 34.57 mg/g and a selectivity factor of 12.96 toward 2,4-dichlorophennoxyacetic acid at 500 mg/l concentration. Permeability experiments indicated that molecularly imprinted membrane can recognize and absorb 2,4-dichlorophennoxyacetic acid from aqueous solutions’ selectively.     

Noncovalent imprinted microspheres: Preparation,evaluation and selectivity of DBU template

1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) imprinted polymer was prepared as microspheres by precipitation polymerization method to obtain molecular recognition systems based on the noncovalent interactions between DBU template, methacrylic acid (MAA), and ethylene .glycol dimethacrylate (EDMA) in acetonitrile. ¹H NMR analysis of DBU/MAA mixture has been performed and hydrogen bonding interactions have been established. Microspheres have been characterized by FTIR studies with evidence of DBU linkage in polymer particles and by Scanning Electron Microscopy (SEM) to study their morphological properties. How pH values affect the binding capacity of imprinted polymer during the binding stage has been also discussed and results suggest that imprinted poly‐(MAA‐EDMA) behavior is related to the influence of DBU basicity during rebinding processes and the optimum pH value for binding has been found around neutral range. Binding ability of the imprinted polymer towards different concentration of DBU buffered solutions has been evaluated and compared with binding ability of the non‐imprinted polymer. A more sensitive response to the template in the imprinted system suggests that a reasonable number of specific binding sites is formed. Finally, differential selectivity towards other less strong than DBU nitrogen bases, such as pyridine, imidazole, and 1,5‐diazabicyclo[4.3.0]non‐5‐ene (DBN) has been also discussed. Our results indicate that both specific sites and basic properties are involved in the rebinding process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Tocopherol‐targeted membrane adsorbents prepared by hybrid molecular imprinting

A hybrid molecular imprinting technique for a tocopherol target enabled the preparation of novel membrane adsorbents. α‐Tocopherol methacrylate was used as a functional monomer, and molecular imprinted polymer (MIP) was prepared by copolymerization with divinylbenzene. After the copolymer was granulated, several hybrid molecular imprinted membranes (HMIP) containing the polymer powders were prepared by using polymer scaffolds such as polysulfone (PSf), cellulose acetate (CA), and nylon (Ny). All HMIP membranes prepared by the phase inversion technique showed selective binding of α‐tocopherol (α‐Toc) over its derivative, δ‐tocopherol (δ‐Toc). The imprint efficiencies were 0.49 for the MIP powder and 0.60, 0.64, and 0.53 for the PSf, Ny, and CA‐HMIP systems, respectively. These HMIP membranes retained their binding capacity without losing significant selectivity relative to the MIP powder. Our results demonstrated that the α‐Toc‐imprinted sites were responsible for the selective binding of the target molecules by the HMIP membranes. The membranes' binding behavior was analyzed using Scatchard plots; a heterogeneous distribution of binding sites was observed in both the MIP polymer and HMIP membranes. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

胆固醇分子印迹聚合微球的制备及其吸附性能

以胆固醇为模板分子、甲基丙烯酸为功能单体、乙二醇二甲基丙烯酸酯为交联剂,在甲苯-乙腈(9:1, j)混合溶剂中沉淀聚合制备了分子印迹聚合物微球. 采用平衡结合法和Scatchard模型评价了该聚合微球的结合性,考察了其吸附行为. 结果表明,胆固醇分子印迹聚合微球中形成两类不同的结合位点,得到高亲和性结合位点的离解常数和最大表观吸附量分别为0.86 mmol/L和80.4 mmol/g,低亲和性结合位点解离常数和最大表观吸附量分别为0.39 mmol/L和61.6 mmol/g. 此方法合成的分子印迹微球对胆固醇有较好的结合性能,可用于胆固醇的分析检测.     

利福平分子印迹聚合物的制备及其吸附行为

以利福平为模板分子、甲基丙烯酸为功能单体、乙二醇二甲基丙烯酸酯为交联剂,制备了利福平分子印迹聚合物. 采用平衡结合方法和Scatchard模型评价了该聚合物的结合特性,考察了其吸附行为. 结果表明,利福平分子印迹聚合物中形成了两类不同的结合位点,得到高亲和力结合位点的离解常数和最大表观结合量分别为31.5 mg/mL和23.34 mg/g,低亲和力结合位点的离解常数和最大表观结合量分别为9.22 mg/mL和12.86 mg/g. 实验结果显示,利福平分子印迹聚合物对利福平呈现出了高的选择吸附特性.     

Effect of porogenic solvent on the morphology,recognition and release properties of carbamazepine‐molecularly imprinted polymer nanospheres

This study focus on the effect of the porogenic solvent on the morphology, recognition, and drug release of carbamazepine‐molecularly imprinted polymer nanospheres prepared by precipitation polymerization. The scanning electron microscopy (SEM) images and Brunauer‐Emmett‐Teller (BET) analysis showed that molecularly imprinted polymer (MIP) prepared by acetonitrile exhibited a regular spherical shape at the nanoscale with a high degree of monodispersity, specific surface area of 242 m² g⁻¹, and pore volume of 1 mL g⁻¹, while those using chloroform and toluene produced irregular polymer particles with low specific surface area and pore volume. MIP prepared by acetonitrile/chloroform (1 : 1, v/v) showed mediator texture properties compared to MIPs obtained by acetonitrile or chloroform. Results from saturation and displacement assays indicated that the imprinted nanospheres with binding capacity of 2.85 (mg CBZ/g polymer) had high specific affinity to CBZ in contrast to nonimprinted nanospheres (1.63 mg CBZ/g polymer). The imprinted nanospheres with 2.4 selectivity factor had good recognition to CBZ than analog template of oxcarbazepine. Moreover, release studies showed that 20% of loaded CBZ was released from the imprinted nanospheres within the initial 6 h, while another 80% of CBZ was released in the following 9 days. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

沉淀聚合法制备磺胺二甲嘧啶分子印迹聚合物

以磺胺二甲嘧啶为模板分子,采用沉淀聚合法制备了分子印迹聚合物,并对其选择性和吸附性能进行了研究.等温静态平衡实验结果表明,该印迹聚合物与相应的空白聚合物相比具有高的选择性和亲和性;Scatchard模型分析结果表明,该印迹聚合物对印迹分子存在一种均匀的结合位点,最大表观结合量为31.866 mg/g.