Nickel(II)‐imprinted monolithic columns for selective nickel recognition

Ni²⁺‐imprinted monolithic column was prepared for the removal of nickel ions from aqueous solutions. N‐Methacryloyl‐L ‐histidine was used as a complexing monomer for Ni²⁺ ions in the preparation of the Ni²⁺‐imprinted monolithic column. The Ni²⁺‐imprinted poly(hydroxyethyl methacrylate‐N‐methacryloyl‐L ‐histidine) (PHEMAH) monolithic column was synthesized by bulk polymerization. The template ion (Ni²⁺) was removed with a 4‐(2‐pyridylazo) resorcinol (PAR):NH₃? NH₄Cl solution. The water‐uptake ratio of the PHEMAH–Ni²⁺ monolith increased compared with PHEMAH because of the formation of nickel‐ion cavities in the polymer structure. The adsorption of Ni²⁺ ions on both the PHEMAH–Ni²⁺ and PHEMAH monoliths were studied. The maximum adsorption capacity was 0.211 mg/g for the PHEMAH–Ni²⁺ monolith. Fe³⁺, Cu²⁺, and Zn²⁺ ions were used as competitive species in the selectivity experiments. The PHEMAH–Ni²⁺ monolithic column was 268.8, 25.5, and 10.4 times more selective than the PHEMAH monolithic column for the Zn²⁺, Cu²⁺, and Fe³⁺ ions, respectively. The PHEMAH–Ni²⁺ monolithic column could be used repeatedly without a decrease in the Ni²⁺ adsorption capacity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Toward “Rubbery” nanoparticles

The synthesis of electrically Conducting Natural Rubber (CNR) nanoparticles from natural rubber (cis 1, 4 polyisoprene) by a simple chemical doping technique is reported for the first time. Much before the establishment of conjugation as a precondition for polymers to be conducting a typical nonconjugated polymer like cis 1,4 polyisoprene was shown to develop intrinsic conductivity on doping. However, the possibility of developing conducting nanoparticles of natural rubber by doping has never been explored. Doping of natural rubber solution with Antimony pentchloride is found to lead to the formation of nanosized rubber particles with improved thermal stability and lower degradation characteristics than that of pristine rubber. Transmission electron microscopy and Dynamic Light Scattering experiments revealed a highly uniform dispersion of the particles with sizes in the range of 4 nm. The doped nanoparticles are found to retain “rubbery” properties of natural rubber and therefore these can be rightly termed as Rubber Nano particles. The development of nanoparticles of rubber assumes great significance in that it would lead to hitherto unknown applications for natural rubber in micro applications‐like sensors, and optoelectronics devices to macro applications such as compatible reinforcing fillers for elastomers and plastics to replace conventional fillers like carbon particles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Molecularly imprinted polymer for solid phase extraction of nicotinamide in pork liver samples

Aromatic polyamides and polythioamides with pendent chlorobenzylidine rings were synthesized through direct polycondenzation of 2‐(p‐chlorobenzalimino) terephthalic acid with the diamines 4,4′‐oxidianiline (1a), 4,4′‐methylenediamide (1b), 4,4′‐diaminodiphenyl sulfone (1c), and thioamines 4,4′‐(bisthiourea) diphenyl ether (3a), 4,4′‐(bisthiourea) diphenyl methane (3b), 4,4′‐(bisthiourea) diphenyl sulfone (3c), respectively, in DMF using P(OPh)₃/pyridine. The polymers were precipitated using water as nonsolvent. FTIR and ¹H‐NMR spectroscopic analysis was used to characterize the monomers and polymers. Representative polyamides and polythioamides were used for the removal of heavy metal ions such as Pb(II), Cd(II), Cu(II), and Cr(III) from aqueous solutions. The effects of pH, contact time, and initial concentration on the uptake of metal ions have been investigated. The adsorption capacities under competitive conditions were in the order Pb (II) > Cu (II) > Cr (III) > Cd (II). The adsorbed ions were eluted by treatment with 2N HCl, and the activities of the polymers are retained after fourth regeneration. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Molecularly imprinted polymer membranes for substance‐selective solid‐phase extraction from aqueous solutions

Thin‐layer molecularly imprinted polymer (MIP) composite membranes for selective binding of monocrotophos (MCP) pesticide from aqueous solutions were developed. The procedure was based on commercially available membrane modules that were rinsed with prepolymerization imprinting mixtures. After the in situ polymerization and generation of MIP films on the membranes within the modules, the membranes were evaluated in terms of affinity toward the target molecule MCP. MIP membranes with different porogens and different monomers on Nylon‐6 membranes were prepared. It was shown that MIP membranes synthesized with methacrylic acid as monomer and toluene as porogens on the Nylon‐6 membranes provided a highly selective binding of MCP from aqueous solutions under the optimized elution conditions. With the novel surface modification technique, the low nonspecific binding properties of the microfiltration membrane could successfully be combined with the receptor properties of molecular imprints, yielding substance‐specific MIP composite membranes. The high affinity of these synthetic membranes to MCP pesticide together with their straightforward and inexpensive preparation could be applied in a fast preconcertration step, solid‐phase extraction, by a simple microfitration for the determination of MCP in water. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4468–4473, 2006     

A new microemulsion approach for producing molecularly imprinted polymers with selective recognition cavities for gallic acid

Bulk and microemulsion systems were studied in order to obtain molecularly imprinted copolymers selective for gallic acid. Both systems contained acrylic acid as the functional monomer and ethylene glycol dimethacrylate as crosslinker. Microemulsion formation was confirmed by refractive index measurements and by conductivity analyses. Simple uptake tests revealed higher affinities for the microemulsion polymers; a 3.55 imprinting factor and a 0.275 g gallic acid (g polymer)^–1 adsorption capacity were recorded. Competitive uptake tests, from an oak bark extract, were in agreement with the simple uptake results and BET analyses. Microemulsion polymer particles selectively bind 4.58 times more gallic acid molecules relative to other competitor species.     

Preparation and evaluation of magnetic imprinted polymers for 2,4,6‐trinitrotoluene by surface imprinting

A safe and facile approach for the preparation of magnetic molecularly imprinted polymer nanospheres for 2,4,6‐trinitrotoluene (TNT) recognition is reported. The imprinted nanospheres were synthesized using TNT as the imprinting molecule, acrylamide as the functional monomer, N,N'‐methylenebisacrylamide as the crosslinker and magnetic particles as the support. The structure of the materials was identified via Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy and transmission electron microscopy. Static adsorbing experiments were carried out and Scatchard plot analysis showed that two kinds of receptor sites were formed in the imprinted materials. The adsorption equilibrium constant and the maximum adsorption capacity were evaluated. These results indicated that the imprinted nanospheres have higher adsorption capacity and selectivity for TNT than non‐imprinted polymer nanospheres with the same composition. © 2013 Society of Chemical Industry     

Molecularly imprinted polymers for the selective recognition of l‐phenylalanine based on 1‐buty‐3‐methylimidazolium ionic liquid

To enhance the affinity of 4‐vinyl pyridine to l ‐phenylalanine (l ‐Phe) and convert the imprinting process from the aqueous phase to the organic phase, an oil‐soluble amino acid ionic liquid was introduced as a template. In this study, 1‐butyl‐3‐methylimidazolium α‐aminohydrocinnamic acid salt was first applied to prepared surface molecularly imprinted polymers (MIPs) in acetonitrile for the selective recognition of l ‐Phe. Fluorescence quenching analysis of the functional monomer on the template was investigated under different conditions to study the imprinting mechanism. Several binding studies, such as the sorption kinetics, sorption thermodynamics, and solid‐phase extraction application, and the chiral resolution of racemic phenylalanine were investigated. The binding isotherms were fitted by nonlinear regression to the Freundlich model to investigate the recognition mechanism. The affinity distribution analysis revealed that polymers imprinted by ionic liquid showed higher homogeneous binding sites than those imprinted by l ‐Phe. The competition tests were conducted by a molecularly imprinting solid‐phase extraction procedure to estimate the selective separation properties of the MIPs for l ‐Phe. The target MIP was shown to be successfully for the separation of l ‐Phe from an amino acid mixture. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42485.     

Functionalization of cellulose as imprinted adsorbent for selective adsorption of matrine

A novel molecular imprinted polymer (MIP) based on cellulose is fabricated for separation of matrine. Cellulose graft copolymer was first synthesized from cotton linter by atom transfer radical polymerization in ionic liquid with the acrylamide as monomer. Then, the prepared graft copolymer underwent sulfomethylation and subsequent crosslinking in the matrine solution. Effects of the parameters on the reaction degree were discussed, and the structural, component, and morphological characterization of the products were also conducted. The ability of the obtained cellulose-based MIP (MIP-SPAM) to adsorb matrine was evaluated by batch adsorption. Results showed that the sorption process was pH dependent, spontaneous, endothermic, and followed the Langmuir adsorption isotherm. Kinetics study revealed that pseudo-second-order was closed to the experimental data and both of the membrane diffusion and intraparticle diffusion controlled the matrine adsorption. Moreover, MIP-SPAM possessed higher selective sorption property for matrine compared to the corresponding nonimprinted polymer. Finally, the MIP-SPAM could be repeatedly used for five times without any significant loss in the initial binding affinity. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48392.     

Preparation of molecularly imprinted polymers: Diethyl(3‐methylureido)(phenyl)methylphosphonate as a dummy template for the recognition of its organophosphate pesticide analogs

A novel compound, diethyl(3‐methylureido)(phenyl)methylphosphonate (DEP), possessing an organophosphate skeleton, was synthesized and used as a dummy template to prepare molecularly imprinted polymers (MIPs) for the recognition of organophosphate pesticide analogs. Computational modeling was used to study the primary intermolecular interactions in the prepolymerization mixture. It was found that the interaction force between DEP and the monomers was hydrogen bonding. A series of MIPs were synthesized with different monomers and were evaluated by adsorption experiments, which showed that methacrylic acid was used as an appropriate monomer and a molar ratio of DEP to MAA of 1 : 9 was optimal. Scatchard analysis showed that there might have been two types of binding sites in the MIPs. DEP and several pesticides were used in molecular recognition specificity tests of DEP–MIP, which exhibited better selectivity and reservation ability for organophosphate pesticides, such as methamidophos and orthene, possessing amino or imino groups and a smaller steric hindrance. On the basis of the use of a dummy molecule as template, the problem of template leakage could be avoided; this, thereby, improved the specificity of analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Molecular‐imprinted nylon membranes for the permselective binding of phenylalanine as optical‐resolution membrane adsorbents

Nylon 6, nylon 6,6, and terephthalic phenylene polyamide (TPPP) were functionalized by phase‐inversion molecular imprinting to add L ‐phenylalanine recognition ability. Formic acid containing 20 wt % nylon and 8 wt % L ‐phenylalanine was used as the solvent for the cast solution of the imprinting process. The resultant porous membranes behaved as membrane adsorbents that separated the L /D mixture of the substrate. The imprinted nylon 6 and nylon 6,6 presented high selectivity to the L ‐form substrate with respect to the TPPP membranes, but the imprinted TPPP membranes showed higher binding capacity with 0.57 μmol/g for L ‐phenylalanine. The apparent partition coefficients of L ‐ and D ‐forms by the imprinted membranes were 6.8, 4.2, and 1.7 for nylon 6, nylon 6,6, and TPPP, respectively. The separation manner of the L ‐ and D ‐forms from the mixture was also confirmed by membrane filtration under 1.5 kgf/cm² of applied pressure. The imprinted nylon 6, nylon 6,6, and TPPP membranes had separation factors of L ‐ and D ‐phenylalanines of 1.1, 1.1, and 1.2, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 620–626, 2005     

印迹水凝胶作为氟尿嘧啶载体的药物缓释性能

以氟尿嘧啶为模板药物,以甲基丙烯酸羟乙酯为骨架单体,以甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,偶氮二异丁腈为引发剂合成印迹水凝胶,并通过扫描电镜、红外光谱及差示热量扫描等测试手段对凝胶进行了表征,结果表明：制备的印迹水凝胶表面无孔、光滑,氟尿嘧啶与其中的单体通过氢键结合成了复合物,同时经处理后凝胶中已不再残留未反应的单体。印迹水凝胶的吸水溶胀性能实验结果显示其吸水溶胀性能随制备中模板药物的含量的增加而增强,同时同一凝胶的溶胀速度与溶胀率随体系pH值的升高而增强。在氟尿嘧啶溶液中测定水凝胶的药物负载量,结果显示：印迹水凝胶的药物负载能力明显强于非印迹水凝胶,同时印迹水凝胶（8∶1）对药物的负载能力强于印迹水凝胶（4∶1）,药物负载量高达0.0914 mg/g。在模拟体液中测试水凝胶对药物的释放效果结果显示：印迹水凝胶对药物的缓释作用明显优于非印迹水凝胶,并且印迹水凝胶（8∶1）对药物的缓释效果优于印迹水凝胶（4∶1）,对药物的释放平缓,同时,释放体系pH值的升高不利于印迹水凝胶的药物缓释效果。     

Molecularly imprinted macroporous polymer monolithic layers for L-phenylalanine recognition in complex biological fluids

In present work, the development of macroporous monolithic layers bearing the artificial recognition sites toward L-phenylalanine has been carried out. The set of macroporous poly(2-aminoethyl methacrylate-co-2-hydroxyethyl methacrylate-co-ethylene glycol dimethacrylate) materials with average pore size ranged in 340–1200 nm was synthesized. The applicability of Hildebrand's and Hansen's theories for the prediction of polymer compatibility with porogenic solvents was evaluated. The dependences of average pore size on theoretically calculated parameters were plotted. The linear trend detected for Hansen's theory has indicated the high suitability of this approach to select appropriate porogens. The synthesized monolithic MIP layers were tested toward the ability to rebind phenylalanine-derivative in microarray format. The influence of such factors as average pore size of the material, the concentration of template molecule in polymerization mixture, interaction time of analyte with its imprinted sites on binding efficiency were studied. The developed materials demonstrated good analyte rebinding from buffer solution with recognition factors 2.5–3.4 depending on the MIP sample. The comparable rebinding efficiency was also detected when the analysis was carried using complex biological media. The selectivity of phenylalanine binding from the equimolar mixture of structural analogues was 81.9% for free amino acid and 91.2% for labeled one.     

Molecularly imprinted polymers: present and future prospective

Molecular Imprinting Technology (MIT) is a technique to design artificial receptors with a predetermined selectivity and specificity for a given analyte, which can be used as ideal materials in various application fields. Molecularly Imprinted Polymers (MIPs), the polymeric matrices obtained using the imprinting technology, are robust molecular recognition elements able to mimic natural recognition entities, such as antibodies and biological receptors, useful to separate and analyze complicated samples such as biological fluids and environmental samples. The scope of this review is to provide a general overview on MIPs field discussing first general aspects in MIP preparation and then dealing with various application aspects. This review aims to outline the molecularly imprinted process and present a summary of principal application fields of molecularly imprinted polymers, focusing on chemical sensing, separation science, drug delivery and catalysis. Some significant aspects about preparation and application of the molecular imprinting polymers with examples taken from the recent literature will be discussed. Theoretical and experimental parameters for MIPs design in terms of the interaction between template and polymer functionalities will be considered and synthesis methods for the improvement of MIP recognition properties will also be presented.     

Direct nanolayer preparation of molecularly imprinted polymers immobilized on multiwalled carbon nanotubes as a surface-recognition sites and their characterization

Molecular imprinting is a method for making artificial receptor sites in a polymer. This article reports the direct nanolayer immobilization of molecularly imprinted polymers (MIPs) on hydroxyl-functionalized multiwalled carbon nanotubes (MWCNTs) without any binder to improve their characteristics. MIPs were formed for hydrochlorothiazide (HCT) as a template on the surface of the MWCNTs with methacrylic acid (functional monomer) and ethylene glycol dimethacrylate (crosslinking agent) with a thermal polymerization technique. The morphology and stability of the immobilized molecularly imprinted polymers on the surface of multiwalled carbon nanotubes (MIPCNTs) was characterized with scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The resulting MIPCNTs demonstrated favorable selectivity, good stability, and a higher adsorption capacity for the template molecule (93.0 μg/mg) compared to products created by bulk polymerization. The adsorption kinetics of HCT at the surface of the MIPCNTs was in agreement with the second-order rate equation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Removal of 2,4,6‐Trinitrotoluene from “Pink Water” Using Molecularly‐Imprinted Absorbent

Molecularly‐Imprinted Polymers (MIPs) were designed, prepared, and tested for the removal of TNT from “pink water”, which contains 2,4,6‐trinitrotoluene (TNT) and other nitrobenzene compounds (NBCs) produced in army ammunition plants. We have investigated the interactions between TNT template and different monomers using molecular modeling and spectrometric methods, which enables us to optimize the MIP compositions. A suspension polymerization method was utilized to prepare MIP beads with an average diameter of 25 µm, and an imprinting effect of 4.3 was achieved. Furthermore, we have constructed a model absorbance reactor using a flash chromatography system, which was successfully used to monitor the removal of TNT and other NBCs on‐line, and the MIP absorbent was regenerated in‐situ. Compared with granular activated carbon, the capacity of the MIP absorbent is 65‐fold higher. In addition, the MIP absorbent can be regenerated easily, and the capacity only decreases by 7 % after four rounds of regeneration. Besides “pink water”, the MIP absorbent can also be used to remove NBCs in the waste stream from TNT production.     

Molecularly imprinted nanoparticles prepared by core‐shell emulsion polymerization

Submicron core‐shell polymer particles, with molecularly imprinted shells, were prepared by a two‐stage polymerization process. Particles of this type, prepared with a cholesterol‐imprinted ethyleneglycol dimethacrylate shell and in the absence of porogen, were found to be 76 nm in diameter with a surface area of 82 m² g⁻¹. Cholesterol uptake from a 1 mM solution in isohexane was measured at both 10 and 30 mg mL⁻¹, with the imprinted polymer showing considerable binding (up to 57%). Imprinted but not hydrolyzed and hydrolyzed nonimprinted polymers showed very low uptakes (≤4.5%) and a phenol‐imprinted polymer showed reduced binding (36%) under the same conditions. Imprinted shells were also prepared over superparamagnetic polymer cores and over magnetite ferrocolloid alone. The cholesterol binding to magnetic particles was very similar to that of equivalent nonmagnetic materials. Magnetic particles could be sedimented in as little as 30 s in a magnetic field. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1851–1859, 2000     

Protein‐imprinted soft‐wet gel composite microspheres with magnetic susceptibility. II. Characteristics

Protein‐imprinted soft‐gel composite microspheres with magnetic susceptibility (MS‐PIGMs) were prepared by inverse suspension polymerization using Fe₃O₄ particles as magnetically susceptible component and bovine serum albumin and lysozyme (Lyz) as templates, respectively. The average content of magnetically susceptible component (Fe₃O₄) inside MS‐PIGMs was determined using thermogravimetric analyzer, and the magnetic characteristics of MS‐PIGMs were measured by vibrating sample magnetometer. The results showed that the resulting MS‐PIGMs had a certain magnetic response to external magnetic fields, and their average content of Fe₃O₄ was 2.08%. Their recognition specificity was investigated using BSA and Lyz as both templates and control molecules and characterized by high‐performance liquid chromatography, and the mechanism of imprinting and recognition was analyzed. It was shown that the resulting BSA imprinted soft‐gel composite microspheres with magnetic susceptibility (BSA‐PIGMs) and Lyz imprinted soft‐gel composite microspheres with magnetic susceptibility (Lyz‐PIGMs). All exhibited good recognition selectivity for their templates, and the relative separation factor (β) was 4.75 and 5.88, respectively. The recognition selectivity of MS‐PIGMs to their templates depended mainly on the synergic action of a large quantity of hydrogen binding being caused by complementation and very close contact of outer surface of proteins with inner surface of “imprinting cavities.” © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006