Non-molecularly Imprinted Polymer Research Articles

Development and Characterization of a Molecularly Imprinted Polymer for the Selective Removal of Brilliant Green Textile Dye from River and Textile Industry Effluents.

In this paper, we present an alternative technique for the removal of Brilliant Green dye (BG) in aqueous solutions based on the application of molecularly imprinted polymer (MIP) as a selective adsorbent for BG. The MIP was prepared by bulk radical polymerization using BG as the template; methacrylic acid (MAA) as the functional monomer, selected via computer simulations; ethylene glycol dimethacrylate (EGDMA) as cross-linker; and 2,2'-azobis(2-methylpropionitrile) (AIBN) as the radical initiator. Scanning electron microscopy (SEM) analyses of the MIP and non-molecularly imprinted polymer (NIP)-used as the control material-showed that the two polymers exhibited similar morphology in terms of shape and size; however, N2 sorption studies showed that the MIP displayed a much higher BET surface (three times bigger) compared to the NIP, which is clearly indicative of the adequate formation of porosity in the former. The data obtained from FTIR analysis indicated the successful formation of imprinted polymer based on the experimental procedure applied. Kinetic adsorption studies revealed that the data fitted quite well with a pseudo-second order kinetic model. The BG adsorption isotherm was effectively described by the Langmuir isotherm model. The proposed MIP exhibited high selectivity toward BG in the presence of other interfering dyes due to the presence of specific recognition sites (IF = 2.53) on its high specific surface area (112 m2/g). The imprinted polymer also displayed a great potential when applied for the selective removal of BG in real river water samples, with recovery ranging from 99 to 101%.

Synthesis and Characterization of MIPs for Selective Removal of Textile Dye Acid Black-234 from Wastewater Sample

Herein, a molecularly imprinted polymer (MIP) was prepared using bulk polymerization and applied to wastewater to aid the adsorption of targeted template molecules using ethylene glycol dimethacrylate (EGDMA), methacrylic acid (MAA), acid black-234 (AB-234), 2,2'-azobisisobutyronitrile (AIBN), and methanol as a cross linker, functional monomer, template, initiator, and porogenic solvent, respectively. For a non-molecularly imprinted polymer (NIP), the same procedure was followed but without adding a template. Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and a surface area analyzer were used to determine the surface functional groups, morphology and specific surface area of the MIP and NIP. At pH 5, the AB-234 adsorption capability of the MIP was higher (94%) than the NIP (31%). The adsorption isotherm data of the MIP correlated very well with the Langmuir adsorption model with Qm 82, 83 and 100 mg/g at 283 K, 298 K, and 313 K, respectively. The adsorption process followed pseudo-second-order kinetics. The imprinted factor (IF) and Kd value of the MIP were 5.13 and 0.53, respectively. Thermodynamic studies show that AB-234 dye adsorption on the MIP and NIP was spontaneous and endothermic. The MIP proved to be the best selective adsorbent for AB-234, even in the presence of dyes with similar and different structures than the NIP.

Development of affinity polymeric particles for the removal of 4-dimethylaminopyridine (DMAP) from active pharmaceutical ingredient crude streams using a green technology

Polymeric particles with affinity for 4-dimethylaminipyridine (DMAP) were developed by molecular imprinting using supercritical carbon dioxide (scCO2) technology, for cleanup of this potentially genotoxic impurity from crude mixtures of Active Pharmaceutical Ingredients (APIs). DMAP-molecularly imprinted polymer (DMAP-MIP) and the respective control, the non-molecularly imprinted polymer (NIP) were produced by free radical polymerization using methacrylic acid as monomer, ethylene glycol dimethacrylate as crosslinker and AIBN as free-radical initiator in scCO2. The materials were obtained in high yield and were characterized chemically, physically and morphologically. Their extraction efficiency was evaluated by dynamic binding experiments using two solutions: i) a solution containing 104 ppm DMAP solution; ii) model pharmaceutical mixture containing 104 ppm of DMAP and 1018 ppm of Mometasone furoate (API). Particles were able to remove 18.3 µmol DMAP/g polymer from a 104 ppm DMAP solution (i) and 1004.6 µmol DMAP/g API (ii). In addition, high recoveries of both DMAP and API were obtained, above 99%.

Elaboration of an Imprinted Polymer Film Based on Chitosan Electrodeposition for the Voltammetric Detection of BPA

A voltammetric sensor for bisphenol A (BPA) detection was developed. It was based on a gold electrode modified by an electrodeposited molecularly imprinted chitosan (CS) film. Fourier Transformed Infrared spectroscopy, scanning electron microscopy and electrochemistry were used to characterize and compare the surface of the molecularly imprinted polymer (MIP) and non-molecularly imprinted polymer (NIP) films. The analytical performance of this biosensor was then established using square wave voltammetry (SWV) of the ferro/ferricyanide redox probe, in the range of −300 and 600 mV. The oxidation peak current was proportional to the logarithm of BPA concentration in the range between 10−3 M to 10−21 M with a limit of detection of 0.67 × 10−21 M. The elaborated sensor showed good repeatability (RSD 2.08%), reusability and recognition of BPA in the presence of similar structural moieties. The proposed sensors were successfully employed to determine BPA in real plastic bottles for drinking water.

Camptothecin-imprinted polymer microspheres with rosin-based cross-linker for separation of camptothecin from Camptotheca acuminata fruit

In this work, camptothecin (CPT) molecularly imprinted polymer (MIP) microspheres were prepared via membrane emulsification-suspension polymerization using ethylene glycol maleic rosinate acrylate as a crosslinker, acrylic acid as a functional monomer, and CPT as a template molecule. The MIPs were characterized by scanning electron microscopy, laser granulometry, nitrogen sorption porosimetry, and thermogravimetric analysis. The results indicated that the MIPs had a regular spherical shape with porous surfaces and particle sizes mainly ranging from 3 to 5 μm. The surface areas of the MIPs and non-molecularly imprinted polymer (NIP) microspheres were 89.44 and 86.91 m2 g−1, respectively, and their respective average pore sizes were 11.42 and 10.84 nm. Furthermore, the MIPs and NIPs exhibited excellent thermal stabilities. The HPLC columns prepared with the MIPs and NIPs as the chromatographic stationary phase showed good fluidity. The effect of the MIP column on CPT was evaluated with HPLC, and the selectivity and separation performance of the MIP and NIP columns for CPT and 10-hydroxycamptothecin were evaluated. The chromatographic thermodynamics and separation mechanism were also studied. Finally, the MIP column was successfully applied to the separation and purification of CPT from an extract of Camptotheca acuminata fruit, and the reusability of the MIP column was also investigated.

Improving affinity of β-cyclodextrin-based molecularly imprinted polymer using room temperature ionic liquid

This paper reported the facile method of improving the affinity of β-cyclodextrins (β-CD)-based molecularly imprinting system by using the effect of interaction of β-CD and room temperature ionic liquids (RTILs). The molecularly imprinting polymers (MIPs) of β-CD matrices were prepared with β-CD, as functional monomer, hexanethylene diisocyante as crosslinker, and using aesculin as a model molecule in a RTIL (1-butyl-3-methylimidazolium tetrafluoroborate) of porogen. The RTILs/DMSO-based MIP (or NIP) showed smaller surface areas but greater pore size than the RTILs/DMSO-free MIP (or NIP). The equilibrium adsorption experiment indicated that the imprinting factor for the β-CD-based MIP prepared with RTILs was 2.25 and 1.19 for the controlled MIP prepared without RTILs. In addition, the values of effective diffusivity (Deff) of aesculin (AN) obtained from the RTILs-assisted β-CD MIP (10−16 cm2/s) was about seven times smaller than those from the RTILs-free controlled β-CD MIP, although the values of free diffusivity (D) of AN were all found in the order of 10−13 cm2/s. When used as release material, the relative bioavailability of the β-CD-based MIP prepared in RTIL displayed a markedly higher value of 399.7% than that of the commercial AN tablet. On the contrary, the β-CD-based non molecularly imprinted polymer (NIP) prepared in RTILs, β-CD-based MIP prepared in non-RTILs and β-CD-based NIP prepared in non-RTILs was only 88.6%, 179.3% and 157.0%, respectively. The results indicated that using RTIL as porogen is an effective approach to improving affinity of β-CD-based MIP.

Novel magnetic multi-templates molecularly imprinted polymer for selective and rapid removal and detection of alkylphenols in water

A novel multi-templates molecularly imprinted polymer (MIP) was prepared on the surface of mesoporous silica coated magnetic graphene oxide (MGO@mSiO2), and applied for the rapid and selective detection of alkylphenol compounds including bisphenol A (BPA), 4-tert-octylphenol (4-tert-OP) and 4-nonylphenol (4-NP) in water. The synthesized composite was characterized by Fourier transform infrared spectrometer, vibrating sample magnetometer, transmission electron microscopy and Brunauer-Emett-Teller surface area analyzer. The MIP showed high adsorption capacity, good selectivity and fast kinetic for these alkylphenols. The maximum adsorption capacities of the MIP for BPA, 4-tert-OP and 4-NP were 16.81, 35.97 and 61.73 mg g−1, respectively, which were significantly higher than those of the non-molecularly imprinted polymer (NIP) due to the imprinting effect. The adsorption of alkylphenols reached equilibrium within 30 min, and followed pseudo-second-order kinetic model and Langmuir model well. The MIP exhibited good sorption selectivity towards BPA, 4-tert-OP and 4-NP, and could be reused 5 times. Furthermore, a new method for ultrasensitive determination of BPA, 4-tert-OP and 4-NP in water by high performance liquid chromatography was developed, using MIP-based magnetic solid-phase extraction coupled with dispersive liquid-liquid microextraction. Under the optimum conditions, the limits of detection (LODs) for BPA, 4-tert-OP and 4-NP were 0.013, 0.010 and 0.010 μg L−1, respectively. The proposed method was used to the detection of BPA, 4-tert-OP and 4-NP in real water samples, with spiked recoveries of 81.5–104.1% and relative standard deviations (RSDs) of 1.0–7.6%, indicating the multi-templates MIP could be a promising adsorbent for separation and analysis of alkylphenols.

Development of itaconic acid-based molecular imprinted polymers using supercritical fluid technology for pH-triggered drug delivery

A novel pH-responsive molecularly imprinted polymer (MIP) based on Itaconic acid:Ethylene glycol dimethacrylate was developed as a potential body-friendly oral drug delivery system for metronidazole (MZ), a pH-independent drug. MIP performance was evaluated in a simulated oral administration situation, at pHs 2.2 and 7.4. Itaconic acid-based copolymers were synthesized using two different molar ratios of template:monomer:crosslinker (T:M:C), 1:5:25 and 1:5:50, in supercritical carbon dioxide (scCO2) in high yields. Further, impregnation of MZ was performed in scCO2 environment. Morphological and chemical properties of the copolymers produced were assessed by SEM, Morphologi G3 and FTIR analyses. Non-molecularly imprinted polymer (NIP) matrices presented swelling over time in opposition to the molecularly imprinted ones. In the scCO2-impregnation process, MIPs showed a significant molecular recognition towards MZ, presenting higher drug uptake ability with MZ loading of 18-61 wt% in MIPs, compared to 7–20 wt% in NIPs. In vitro drug release experiments presented different release profiles at the different pHs, where MZ-MIPs could release higher amounts of MZ at the lowest pH than at pH 7.4.

Contractile Response of Bovine Lateral Saphenous Vein to Ergotamine Tartrate Exposed to Different Concentrations of Molecularly Imprinted Polymer.

Ergot alkaloids, in their active isomeric form, affect animal health and performance, and adsorbents are used to mitigate toxicities by reducing bioavailability. Adsorbents with high specificity (molecularly imprinted polymers: MIP) adsorb ergot alkaloids in vitro, but require evaluation for biological implications. Using ex vivo myography, synthetic polymers were evaluated for effects on the bioactivity of ergotamine tartrate (ETA). Polymers were first evaluated using isotherms. Lateral saphenous veins were collected from 17 steers for four independent studies: dose response of ETA, adsorbent dose response, validation of pre-myograph incubation conditions and MIP/ non-molecularly imprinted polymer (NIP) comparison. Norepinephrine normalized percent contractile response to increasing ETA exhibited a sigmoidal dose response (max: 88.47 and log of the effective molar concentration (EC50) (−log [ETA]) of 6.66 ± 0.17 M). Although sample preparation time affected contractile response (p < 0.001), pre-myograph incubation temperature (39 vs. 21 °C, 1 h) had no effect (p > 0.05). Isothermal adsorption showed a maximum adsorption of 3.27E-008 moles·mg−1 and affinity between 0.51 and 0.57 mg (R2: 0.83–0.92) for both polymers, with no significant difference between polymers (p > 0.05). No significant differences in maximum inhibitory (p = 0.96) and IC50 responses (p = 0.163) between MIP and NIP were noticed. Normalized percent contraction could be predicted from the in vitro adsorption data (R2 = 0.87, p < 0.01), for both polymers. These studies indicate that synthetic polymers are potentially effective adsorbents to mitigate ergot toxicity caused by ergot alkaloids, with little evidence of significant differences between MIP and NIP in aqueous media.

Molecularly Imprinted Polymers (MIP) for Selective Solid Phase Extraction of Celecoxib in Urine Samples Followed by High Performance Liquid Chromatography

In this study, for the analysis of human urine samples, a novel method explained for the determination of celecoxib, a nonsteroidal anti-inflammatory drug (NSAID), using molecularly imprinted solid-phase extraction (MISPE) coupled with high-performance liquid chromatography (HPLC). The synthesis of the MIP was performed by precipitation polymerization in methacrylic acid (MAA), ethylene glycol dimethacrylate (EGDMA), chloroform, 2,2′-azobisisobutyronitrile (AIBN) and celecoxib as the functional monomer, cross-linker monomer, solvent, initiator and target drug, respectively. The celecoxib imprinted polymer was utilized as a specific sorbent for the solid phase extraction (SPE) of celecoxib from samples. The molecularly imprinted polymer (MIP) performance was compared with the synthesized non-molecularly imprinted polymer (NIP). Scanning electron microscopy (SEM), FT-IR spectroscopy, UV-VIS spectrophotometry and thermogravimetric analysis (TGA/DTG) were used for characterizing the synthesized polymers. Moreover, the MISPE procedure parameters such as pH, eluent solvent flow rate, eluent volume and sorbent mass that probably influence the extraction process have been optimized to achieve the highest celecoxib extraction efficiency. The relative standard deviation (RSD %), recovery percent, limit of detection (LOD) and limit of quantification (LOQ) of this proposed method were 1.12%, 96%, 8 µg L -1 and 26.7 µg L -1 , respectively. The proposed MISPE-HPLC-UV method can be used for the separation and enrichment of trace amounts of celecoxib in human urine and biological samples.

Synthesis of adenosine-imprinted microspheres for the recognition of ADP-ribosylated proteins

Core-shell structural adenosine-imprinted microspheres were prepared via a two-step procedure. Polystyrene core particles (CP) were firstly prepared via a reversible addition-fragmentation chain transfer (RAFT) polymerization leaving the iniferter on the surface of the cores, then a molecularly imprinted polymer (MIP) shell was synthesized on the surface of the cores by using acrylamide (AAm) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. The formation and growth of the MIP layer were seen dependent on the initiator (AIBN), AAm and the polymerization time used within the polymerization. SEM/TEM images showed that the dimensions of the cores and shells were 2μM and 44nm, respectively. The MIP microspheres exhibited a fast rebinding rate within 2h and a maximum adsorption capacity of 177μg per gram for adenosine. The adsorption fitted a Langmuir-Freundlich (LF) isotherm model with a KLF value of 41mL/μg and a qm value of 177μg/g for the MIP microspheres. The values were larger than those for a non-molecularly imprinted polymer (NIP) particles (5mL/μg and 88μg/g) indicating a better adsorption ability towards adenosine. The MIP microspheres showed a good selectivity for adenosine with a higher adsorption (683nmol/g) for adenosine than that (91nmol/g, 24nmol/g and 54nmol/g) for guanosine, cytidine and uridine respectively. Further experiment proved that the adenosine-imprinted polymer microspheres also had a good selectivity for ADP-ribosylated proteins that the MIP could extract the ADP-ribosylated proteins from the cell extract samples.

Fabrication of a Selective and Sensitive Sensor Based on Molecularly Imprinted Polymer/Acetylene Black for the Determination of Azithromycin in Pharmaceuticals and Biological Samples.

A new selective and sensitive sensor based on molecularly imprinted polymer/acetylene black (MIP/AB) was developed for the determination of azithromycin (AZM) in pharmaceuticals and biological samples. The MIP of AZM was synthesized by precipitation polymerization. MIP and AB were then respectively introduced as selective and sensitive elements for the preparation of MIP/AB-modified carbon paste (MIP/ABP) electrode. The performance of the obtained sensor was estimated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Compared with non-molecularly imprinted polymer (NIP) electrodes, NIP/ABP electrodes, and MIP-modified carbon paste electrodes, MIP/ABP electrode exhibited excellent current response toward AZM. The prepared sensor also exhibited good selectivity for AZM in comparison with structurally similar compounds. The effect of electrode composition, extraction parameters, and electrolyte conditions on the current response of the sensor was investigated. Under the optimized conditions, the prepared sensor showed two dynamic linear ranges of 1.0 × 10−7 mol L−1 to 2.0 × 10−6 mol L−1 and 2.0 × 10−6 mol L−1 to 2.0 × 10−5 mol L−1, with a limit of detection of 1.1 × 10−8 mol L−1. These predominant properties ensured that the sensor exhibits excellent reliability for detecting AZM in pharmaceuticals and biological fluids without the assistance of any separation techniques. The results were validated by the high-performance liquid chromatography–tandem mass spectrometry method.

A molecularly imprinted polymer as the sorptive phase immobilized in a rotating disk extraction device for the determination of diclofenac and mefenamic acid in wastewater

The microextraction of diclofenac and mefenamic acid from water samples was performed by using rotating disk sorptive extraction (RDSE) with molecularly imprinted polymer (MIP) as the sorptive phase. The MIP was synthesized from the monomer 1-vinylimidazol (VI) together with the cross-linker divinylbenzene (DVB) using diphenylamine as the template molecule. Scanning electron microscopy (SEM) analyses of the MIP revealed clusters of spherical particles having a narrow size distribution, with diameters of approximately 1 μm.The optimized extraction conditions involved a disk rotation velocity of 3000 rpm, an extraction time of 120 min, a sample volume of 50 mL, and a sample pH of 2 as well as 25 mg of MIP immobilized in the disk. Desorption of the extracted analytes was performed with 5 mL of methanol for 10 min. Analysis by gas chromatography-mass spectrometry (GC–MS) was carried out after derivatization of the analytes with N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA).Nonmolecularly imprinted polymer (NIP) was also synthesized for comparison. It was observed that under the same conditions, MIP extracted significantly more NSAIDs containing diphenylamine (or part of this molecule) in their structure than NIP. Higher significant differences between MIP and NIP were observed for diclofenac, mefenamic acid and paracetamol, clearly indicating the effect of the template on the extraction.Recoveries of the method were between 100 and 112%, with relative standard deviations of 5–6%. The limits of detection were between 60 and 223 ng L−1. Water samples from a wastewater treatment plant (WWTP) of Santiago de Chile, were found to contain concentrations of these acidic drugs between 1.6 and 4.3 μg L−1 and between 1.4 and 3.3 μg L−1 in the influent and effluent, respectively.

An electrochemical sensor for the determination of phoxim based on a graphene modified electrode and molecularly imprinted polymer

The electrochemical impedance spectra of Fe(CN)63−/4− at NIP/graphene/GCE (a), MIP/GCE (b), the bare GCE (c), and MIP/graphene/GCE (d).

Rapid fabrication of molecularly imprinted polymer fibers for solid phase microextraction of bisphenol A

The rapid preparation of molecularly imprinted polymer (MIP) fibers was reported using bisphenol A (BPA) as the template molecular, acetonitrile (ACN) as the porogenic solvent, α-methacrylic acid (MAA) as the functional monomer, ethylene dimethacrylate (EDMA) as the crosslinker, and azodiisobutyronitrile (AIBN) as the thermal initiator. It was carried out within a capillary of 530 µm inner diameter (I. D.) by microwave irradiation in 7 min. The resulted BPA-MIP fibers were pushed out from the capillary, eluted in a vial and inserted in the capillary again followed by the application of the solid phase microextraction (SPME) procedure. The extraction performance was investigated in detail by varying the molar ratios between the template and the monomer (BPA/MAA), the concentration of NaCl, the extraction and desorption time, the pH value and the desorption solvents. The selectivity of the prepared MIP and non-molecularly imprinted polymer (NIP) fibers was comparatively evaluated by selecting two structurally-related compounds, phenol (P) and 4-phenylphenol (PP), and non-analogue dicyandiamide (DCD). The established method was successfully applied for the pretreatment and determination of BPA from beverage samples coupled to high performance liquid chromatography (HPLC). Under the optimal conditions, the linear range of BPA was 10-400 µg/L; the detection limit (LOD) was 0.45 µg/L and the recoveries spiked in the mineral water were 88.4%-102. 8%. The results demonstrated that the developed method can determine BPA in real samples with some advantages of simple pretreatment, rapid analysis, low limit of detection and low consumption of materials.

Development of a Molecularly Imprinted Modified Electrode to Evaluate Phenacetin Based on the Preconcentration of Acetaminophen

A glassy carbon electrode modified with a molecularly imprinted polymer (MIP) containing phenacetin recognition sites is introduced. The phenacetin-selective MIP was synthesised based on the electropolymerisation of pyrrole in a 1:1 (v/v) water/ethanol with HClO4 solution. The MIP-modified electrode showed higher recognition ability in comparison with a bare electrode for procaine and aminopyrine, reported to electrochemically interfere in the quantification of phenacetin in cocaine samples. In addition, the MIP was able to preconcentrate one of the intermediates of the phenacetin electrochemical oxidation, acetaminophen, indicating the possibility of monitoring phenacetin based on the acetaminophen oxidation. The acetaminophen oxidation peak is 15 times more detectable compared to the signal obtained by the non-molecularly imprinted polymer (NIP), and it occurs 450 mV below the phenacetin electrochemical oxidation signal. These achieved characteristics decrease the possibility of interference from other electrochemical reactions that may occur in the same potential range as phenacetin electrochemical process.