Magnetic Molecularly Imprinted Polymers Research Articles

Development of a Chemically Modified Electrode with Magnetic Molecularly Imprinted Polymer (MagMIP) for 17-β-Estradiol Determination in Water Samples

The present work consisted of the development of an electrode based on carbon paste modified with magnetic molecularly imprinted polymer (CPE-MagMIP) for 17-β-estradiol (E2) detection. The incorporation of magnetic material (MagMIP) improved sensor performance, an increase of over 317%. The proposed method resulted in a linear response range from 0.5 to 14.0 μM, and the detection limit (LOD) and quantification limit (LOQ) were equal to 0.13 and 0.44 μM, respectively. Under optimized conditions, the developed sensor obtained satisfactory parameters in E2 determination in water samples, demonstrating selectivity, accuracy, and precision, making it a promising method for monitoring E2 in environmental samples.

Preparation and Adsorption Properties of Magnetic Molecularly Imprinted Polymers for Selective Recognition of 17β-Estradiol

In this paper, magnetic molecularly imprinted polymers (MMIPs) were fabricated on the surface of Fe3O4 by surface molecular imprinting technology, which can selectively adsorb 17β-estradiol (E2). The optimized experiments demonstrated that MMIPs possessed the best adsorption capacity when methanol was used as the solvent and MAA was used as the crosslinking agent, with a molar ratio of E2: MMA: EGDMA as 1:4:50. SEM, FTIR, and XRD were employed to investigate the morphologies of MMIPs and the results demonstrated that the MMIPs that can selectively adsorb E2 were successfully prepared on Fe3O4 particles. The adsorption experiments showed that 92.1% of E2 was adsorbed by the MMIPs, which is higher than the magnetic non-molecularly imprinted polymers (MNIPs). The Freundlich isotherm model was more suitable to describe the adsorption process of E2 by MMIPs. Meanwhile, MMIPs had a better recognition ability for E2 and its structural analogs such as estrone and estriol. The MMIPs still had good adsorption performance after methanol regeneration five times. The prepared MMIPs had the advantages of efficient adsorption ability and high reusability, so they can be applied for selective recognition and removal of E2.

Doxorubicin imprinted magnetic polymethacrylamide as a pH-sensitive anticancer nanocarrier

Molecularly imprinted polymers (MIPs) are efficient and rapidly growing nano-platforms in different biomedical applications. In this study, the surface imprinting approach was used to prepare nanoparticles of magnetic doxorubicin (DOX) imprinted polymer by precipitation polymerization protocol in water. The synthesized magnetic MIPs (MMIP) was used as the doxorubicin (DOX) delivery nanocarrier with high drug loading and pH responsivity. Characterization of the prepared materials was performed by the Fourier Transform Infrared (FT-IR) spectroscopy and Scanning Electron Microscopy (SEM), Thermal Gravimetric Analysis (TGA), X-Ray Diffraction (XRD), Dynamic Light Scattering (DLS), and zeta potential (ZP). The in vitro studies on DOX loading and release indicate that the highest value of DOX was released through a sustained profile in tumor tissue conditions (pH 5, 41 °C) than normal physiological environmental (pH 7.4, 37 °C). Remarkably, the cytotoxicity study demonstrated that the DOX-loaded MMIP has notable cytotoxicity against A549 cells. According to the obtained results, the prepared MMIP could potentially be proposed as a promising candidate for anticancer drug delivery systems.

A Novel Synthesis of a Magnetic Porous Imprinted Polymer by Polyol Method Coupled with Electrochemical Biomimetic Sensor for the Detection of Folate in Food Samples

The present study reports the development and application of a novel, sensitive, and selective voltammetric sensor for the quantitation of folate or vitamin B9 in foodstuffs. The sensor was made from magnetic molecularly imprinted polymers (MMIPs), which were synthesized by the core–shell method using magnetite nanoparticles obtained by the polyol method. The MMIP-based sensor was used for the selective and specific detection of folate in different food samples. The MMIP material was constructed using magnetic water-dispersible nanomaterial, which was prepared by immersing iron (III) acetylacetonate in tri-ethylene-glycol (TEG) solvent. The magnetic water-dispersible nanomaterial was then subjected to polymerization using allyl alcohol as a functional monomer, ethylene-glycol-dimethacrylate (EGDMA) as a cross-linking agent, and 2,2-Azobisisobutyronitrile (AIBN) as a radical initiator. The proposed magnetic materials were characterized by Brunauer–Emmett–Teller (BET), field emission gun scanning electron microscopy (FEG-SEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM) analysis. The quantification of folate was performed by square wave voltammetry under optimized conditions using 15 mg of MMIPs and 85 mg of carbon paste. The modified electrode presented a linear dynamic range (LDR) of 2.0–12 µmol L−1 and a limit of detection (LOD) of 1.0 × 10−7 mol L−1 in 0.1 mol L−1 acetate buffer solution (pH 4.0). The proposed sensor was successfully applied for folate detection in different food samples, where recovery percentages ranging from 93 to 103% were obtained. Finally, the results obtained from the analysis of selectivity showed that the modified biomimetic sensor is highly efficient for folate determination in real food samples. Adsorption tests were used to evaluate and compare the efficiency of the MMIPs and magnetic non-molecularly imprinted polymer (MNIPs)—used as control material, through the application of HPLC as a standard method.

Development of magnetic molecularly imprinted polymers for the extraction of salivary pepsin prior to analysis by a novel HPLC-SEC method

Salivary pepsin is a very important and selective biomarker for gastroesophageal reflux disease and high concentrations in the saliva of potential patients can provide a very useful and non-invasive diagnostic tool. Therefore, this study focused on the development of new and highly selective magnetic molecularly imprinted polymers (MIPs) for the extraction of pepsin from human saliva samples. The developed MIPs provide a stable, cost-effective, and reusable synthetic method of extraction for pepsin. Surface imprinting technique was applied for the synthesis of MIPs to provide a wider surface area and faster binding/release of pepsin, since all the binding sites are allocated on the surface of iron oxide nanoparticles. Methacrylic acid was used as functional monomer, ethylene glycol dimethacrylate as cross linker, and deionised water as a porogen. The imprinting procedure was meticulously optimised to reach the highest possible binding indicated by the value of binding capacity Q which reached (190 mg g−1) and an imprinting factor of 1.34, calculated in comparison to non-imprinted polymers (NIPs). Moreover, the surface morphology, thermal stability as well as the binding properties were characterised to ensure validity. The developed MIPs were applied successfully for dispersive solid phase extraction of pepsin from saliva samples. Consequently, a novel, highly sensitive and simple HPLC-SEC method was developed for the quantitation of pepsin fragments extracted using MIPs. The method was optimised and validated according to ICH guidelines where the linearity ranged from 5 to 150 μg mL−1 in saliva samples with LOD reaching down to 0.6 μg mL−1 which is comparable to the low concentrations of pepsin expected to be found in real saliva samples. The developed system enables the accurate extraction and determination of salivary pepsin with recoveries reaching to 98%. Therefore, this system shows potential as an efficient and reliable testing method for pepsin.

DFT-assisted design inspired by loofah-derived biomass carbon decorated CoFe-CoFe2O4 conjugated molecular imprinting strategy for hazardous thiamphenicol analysis in spiked food

Inspired by the porous microstructure of biomass carbon (BC) and the high adsorption properties of magnetic nanomaterials. A novel electrochemical sensor was developed for the selective assay of thiamphenicol (TAP) in fresh milk, honey, and meat samples by the preconcentration with magnetic molecularly imprinted polymer (MIP) based on differential pulse voltammetry (DPV). The magnetic MIP sensor (MIP/BC/CoFe-CoFe2O4/GCE) was fabricated by coupling CoFe-CoFe2O4 particles embedded loofah sponges derived BC with MIP film-decorated glassy carbon electrode (GCE). Theoretical simulation and quantum calculations based on density functional theory (DFT) accelerate the prediction and selection of rational functional monomers, as well as the ratio of template molecules to monomers. The surface structure, elemental composition, and electrochemical behavior were characterized by XRD, XPS, SEM, TEM, CV, and EIS, respectively. Various factors such as the amount of BC/CoFe-CoFe2O4, monomer/template ratio, polymerization cycles, pH value, elution time, and incubation time have been optimized to enhance the performance of the sensor. Under the optimal conditions, the current response intensities have three segments of good linear relationships with the TAP concentrations in the range of 0.01–2.0 µM (R2 =0.9930) and 2–400 µM (R2 =0.9955) as well as 400–5000 µM (R2 =0.9900) with an ultralow detection limit (LOD, S/N = 3) of 0.003 µM. Besides, the magneto-actuated electrochemical sensor exhibited outstanding analytical performance, i.e., excellent reproducibility and repeatability, ideal stability, and superior anti-interference ability. Moreover, the reliable recoveries (95.11%−105.00%) and the ideal relative standard deviations (RSDs) (1.2%−4.9%) for TAP determination in husbandry samples demonstrated that our developed sensor has good potential in the application.

A deep eutectic solvent magnetic molecularly imprinted polymer for extraction of laminarin from seaweeds.

Magnetic molecular imprinted polymers (MIPs) based on 4-vinylbenzyltrimethylammonium chloride (VBTAC) and 4-vinylbenzoic acid (VBA) deep eutectic solvent as dual functional monomers was successfully synthesized for the specific recognition of laminarin. The MIPs were characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, and vibrating sample magnetometer analysis. The results showed that the MIPs were spheres of a uniform size, with the surface rich in cavities and excellent superparamagnetism properties. The adsorption experiments showed that MIPs conform to pseudo-second-order kinetics and Langmuir isotherm adsorption. The maximum adsorption capacity under optimal conditions was 322.58μg·mg-1 and the imprinting factor was 2.13. Under the optimized conditions, the limit of detection (LOD) of the developed material was 6.6µM. Linearity of the material was obtained within the range 20-800µM with a coefficient of determination (r2) being better 0.999. Relative standard deviations (RSDs) were less than 3.96%, and satisfactory recoveries were between 94.55 and 97.39%. The actual sample analysis manifested that MIPs could effectively separate laminarin from Laminarin japonica Aiesch.

Magnetic Molecularly Imprinted Polymers for the Rapid and Selective Extraction and Detection of Methotrexatein Serum by HPLC-UV Analysis.

In this work, novel selective recognition materials, namely magnetic molecularly imprinted polymers (MMIPs), were prepared. The recognition materials were used as pretreatment materials for magnetic molecularly imprinted solid-phase extraction (MSPE) to achieve the efficient adsorption, selective recognition, and rapid magnetic separation of methotrexate (MTX) in the patients’ plasma. This method was combined with high-performance liquid chromatography–ultraviolet detection (HPLC–UV) to achieve accurate and rapid detection of the plasma MTX concentration, providing a new method for the clinical detection and monitoring of the MTX concentration. The MMIPs for the selective adsorption of MTX were prepared by the sol–gel method. The materials were characterized by transmission electron microscopy, Fourier transform-infrared spectrometry, X-ray diffractometry, and X-ray photoelectron spectrometry. The MTX adsorption properties of the MMIPs were evaluated using static, dynamic, and selective adsorption experiments. On this basis, the extraction conditions were optimized systematically. The adsorption capacity of MMIPs for MTX was 39.56 mgg−1, the imprinting factor was 9.40, and the adsorption equilibrium time was 60 min. The optimal extraction conditions were as follows: the amount of MMIP was 100 mg, the loading time was 120 min, the leachate was 8:2 (v/v) water–methanol, the eluent was 4:1 (v/v) methanol–acetic acid, and the elution time was 60 min. MTX was linear in the range of 0.00005–0.25 mg mL−1, and the detection limit was 12.51 ng mL−1. The accuracy of the MSPE–HPLC–UV method for MTX detection was excellent, and the result was consistent with that of a drug concentration analyzer.

Biodegradable Magnetic Molecularly Imprinted Anticancer Drug Carrier for the Targeted Delivery of Docetaxel.

Molecularly imprinted biodegradable polymers are receiving considerable attention in drug delivery due to their ability of targeted recognition and biocompatibility. This study reports the synthesis of a novel fluorescence-active magnetic molecularly imprinted drug carrier (MIDC) using a glucose-based biodegradable cross-linking agent for the delivery of anticancer drug docetaxel. The magnetic molecularly imprinted polymer (MMIP) was characterized through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy, and vibrating sample magnetometry (VSM). The MMIP presented a magnetization value of 0.0059 emu g–1 and binding capacity of 72 mg g–1 with docetaxel. In vitro and in vivo studies were performed to observe the effectiveness of the MIDC for drug delivery. The cell viability assay suggested that the MMIP did not present toxic effects on healthy cells. The magnetic property of the MMIP allowed quick identification of the drug carrier at the target site by applying the external magnetic field to mice (after 20 min of loading) and taking X-ray images. The novel MMIP-based drug carrier could thus deliver the drug at the target site without affecting the healthy cells.

A Core-Shell Amino-Functionalized Magnetic Molecularly Imprinted Polymer Based on Glycidyl Methacrylate for Dispersive Solid-Phase Microextraction of Aniline

A core-shell amino-functionalized glycidyl methacrylate magnetic molecularly imprinted polymer (MIP) was synthesized by the suspension polymerization/surface imprinting method and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), mercury porosimetry, nitrogen gas adsorption–desorption, and elemental analysis. This MIP was used as the sorbent in dispersive solid-phase microextraction (DSPME) of aniline from textile wastewater prior to high-performance liquid chromatography-mass spectrometry (HPLC-MS) measurements. Since aniline is toxic and a probable human carcinogen, its determination in water is of great significance. This is a challenging task because aniline is usually present at trace levels. The effects of different DSPME variables on the preconcentration efficiency have been studied by using the Plackett–Burman screening design of experiments (DoE) followed by response surface methodology optimization using the Box-Behnken design. Thus, DoE enabled the investigation of several variables simultaneously. Under optimized conditions, aniline was effectively and selectively separated by a small amount of the DSPME sorbent and detected in real textile wastewater samples. The method detection limit of 1 ng mL−1 was attained, with good method linearity and acceptable recovery and precision. The results showed that the studied MIP could be a reliable DSPME sorbent for efficiently analyzing trace aniline in real wastewater samples.

Factors Affecting the Analytical Performance of Magnetic Molecularly Imprinted Polymers.

During the last few years, separation techniques using molecular imprinting polymers (MIPs) have been developed, making certain improvements using magnetic properties. Compared to MIP, Magnetic molecularly imprinted polymers (MMIPs) have high selectivity in sample pre-treatment and allow for fast and easy isolation of the target analyte. Its magnetic properties and good extraction performance depend on the MMIP synthesis step, which consists of 4 steps, namely magnetite manufacture, magnetic coating using modified components, polymerization and template desorption. This review discusses the factors that will affect the performance of MMIP as a selective sorbent at each stage. MMIP, using Fe3O4 as a magnetite core, showed strong superparamagnetism; it was prepared using the co-precipitation method using FeCl3·6H2O and FeCl2·H2O to obtain high magnetic properties, using NH4OH solution added for higher crystallinity. In magnetite synthesis, the use of a higher temperature and reaction time will result in a larger nanoparticle size and high magnetization saturation, while a higher pH value will result in a smaller particle size. In the modification step, the use of high amounts of oleic acid results in smaller nanoparticles; furthermore, determining the correct molar ratio between FeCl3 and the shielding agent will also result in smaller particles. The next factor is that the proper ratio of functional monomer, cross-linker and solvent will improve printing efficiency. Thus, it will produce MMIP with high selectivity in sample pre-treatment.

Development of magnetic molecularly imprinted solid-phase extraction and ultra-high performance liquid chromatography tandem mass spectrometry for rapid and selective determination of urinary diphenyl phosphate of college students

Organophosphate esters (OPEs), known as novel alternative flame retardants, are a class of environmental endocrine disruptors. Long-term exposure to OPEs may bring a non-negligible health risk to human. Urinary OPE metabolites (mOPEs) are generally used as biomarkers to evaluate the internal exposure to OPEs. Diphenyl phosphate (DPHP), the main metabolite of aryl-OPEs, exhibited high detection rates and concentrations in urine samples. To establish a selective and simple analytical method for biomonitoring urinary DPHP, a specific magnetic molecular imprinted polymer (MMIP) was fabricated via a sol-gel method. Under optimum magnetic solid-phase extraction (MSPE) conditions, the resultant MMIP exhibited selective recognition ability, ideal adsorption capacity and good reusability on urinary DPHP enrichment. The developed MSPE method coupled with ultra-high performance liquid chromatography tandem mass spectrometry (U-HPLC-MS/MS) exhibited good precision and accuracy (spiked recoveries of 85.8%-109% with relative standard deviations (RSDs) ranged from 5.1%-13%), low detection limit of 0.035 ng/mL, and negligible matrix inhibition. Then we used this proposed method to detect urinary DPHP levels of recruited 30 college students and investigate the time variability and potential determinants. All urine samples revealed the presence of DPHP at a median concentration of 0.56 μg/g Creatinine (Cr). Moderate reproducibility of DPHP level was observed in first morning urine samples (ICC>0.40). Significant correlations were found between urinary DPHP levels and gender (β=0.72; 95% CI: 0.48∼0.96), sampling time (β=0.36; 95% CI: 0.08∼0.65) as well as the frequency for take-out food (β=0.45; 95% CI: 0.07∼0.74) (p< 0.05). Hence, a fast and sensitive MSPE-U-HPLC-MS/MS method was successfully built to quantify urinary DPHP.

Dual-Template Magnetic Molecularly Imprinted Polymer for Simultaneous Determination of Spot Urine Metanephrines and 3-Methoxytyramine for the Diagnosis of Pheochromocytomas and Paragangliomas.

A novel dual-template magnetic molecularly imprinted polymer (MMIP) was synthesized to extract normetanephrine (NMN), metanephrine (MN) and 3-methoxytyramine (3-MT) from spot urine samples. As the adsorbent of dispersive solid-phase extraction (d-SPE), the MMIP was prepared using dopamine and MN as dual templates, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the crosslinking reagent and magnetic nanoparticles as the magnetic core. NMN, MN, 3-MT and creatinine (Cr) in spot urine samples were selectively enriched by d-SPE and detected by HPLC-fluorescence detection/ultraviolet detection. The peak area (A) ratios of NMN, MN and 3-MT to Cr were used for the diagnosis of pheochromocytomas and paragangliomas (PPGLs). The results showed that the adsorption efficiencies of MMIP for target analytes were all higher than 89.0%, and the coefficient variation precisions of intra-assay and inter-assay for the analytes were within 4.9% and 6.3%, respectively. The recoveries of the analytes were from 93.2% to 112.8%. The MMIP was still functional within 14 days and could be reused at least seven times. The d-SPE and recommended solid-phase extraction (SPE) were both used to pretreat spot urine samples from 18 PPGLs patients and 22 healthy controls. The correlation coefficients of ANMN/ACr and AMN/ACr between d-SPE and SPE were both higher than 0.95. In addition, the areas under the receiver operator curves for spot urine ANMN/ACr, AMN/ACr and plasma free NMN and MN were 0.975, 0.773 and 0.990, 0.821, respectively, indicating the two methods had the similar performances. The d-SPE method took only 20 min, which was effective in clinical application.

Determination of testosterone in serum by magnetic molecularly imprinted polymer-coupled nano-ESI-MS

Monitoring clinical biomarkers, such as testosterone in serum, is important for disease assessment. Due to the very low concentration of testosterone in serum, we have developed a new strategy for its enrichment in serum samples by magnetic molecularly imprinted polymers (MMIPs) technology and detection by nano-electrospray ionization mass spectrometry (Nano-ESI-MS). Testosterone was selectively extracted and enriched by the imprinted polymers on the surface of magnetic particles and the complex matrix was eliminated from the serum. The linear calibration curve was in the range of 0.1–10 μg/L and the limit of detection was 11.4 ng/L. The recovery and repeatability of the spiked serum were satisfactory. These results demonstrate that the proposed method is a promising approach for quantitative analysis of testosterone in serum.

Preparation and characterization of magnetic molecularly imprinted polymer for specific adsorption of wheat gliadin

In this study, a magnetic molecularly imprinted polymers (MIPs) was successfully synthesized by surface imprinting technology for the specific recognition of wheat gliadin (GLI). MIPs showed an obvious hierarchical characteristic by investigations of micromorphology, the magnetic Fe3O4 core were wrapped with SiO2 layer (approximately 40 nm) and imprinted layer (approximately 10 nm). The results of vibrating sample magnetometer (VSM) proved the superparamagnetism of MIPs, which was contributed to the rapid magnetic separation. Furthermore, MIPs displayed excellent selective adsorption ability for GLI through adsorption kinetic model, adsorption isotherm model and adsorption selectivity experiment. The saturated adsorption capacity of MIPs to GLI was 73.55 mg/g under the optimized conditions and the imprinting factor was 3.10. The high performance liquid chromatography (HPLC) manifested that the MIPs were successfully applied to separate template GLI from gluten, reflecting the excellent adsorption specificity of MIPs. Therefore, this research provided a promising method for rapidly separation and specific adsorption of GLI.

Impact of structure and magnetic parameters of nanocrystalline cores on surface properties of molecularly imprinted nanoconjugates for analysis of biomolecules – A case of tyramine

In this paper, the investigations were carried out to reveal the complex nature of the nanocrystalline magnetic cores and to validate the hypothesis that magnetic molecularly imprinted polymer (MMIP) could be used as an effective sorbent during analysis of biomolecules but the adsorbate-sorbent process is independent from the amount of siloxane functionalized magnetite core (Fe3O4@SiO2-MPS). For that purpose, molecularly imprinted shell layer composed from poly(methacrylic acid-co-ethylene glycol dimethacrylate) was conjugated to various amounts of Fe3O4@SiO2-MPS. Magnetic measurements showed single-domain-type magnetic behavior for all materials. Thermal decomposition process revealed different enthalpies (110 to 279 J g−1) with the highest value for MMIP prepared from the lowest amount of Fe3O4@SiO2-MPS. The morphological and structural analyses proved a presence of single magnetite crystallite and elemental mapping confirmed core–shell structure. The binding capacities for MMIPs revealed similar values (0.897 ± 0.114 to 1.019 ± 0.129 µg g−1) and specificity (IF: 3.36 to 3.99). The MMIP sorbent was used to determine model biomolecule of tyramine in wine in the validated analytical method, proving the stability of sorbent. The lower tyramine levels were found in Chilean and Australian wines (0.42 ± 0.03 and 0.15 ± 0.01 mg L-1, respectively) and higher in French one (7.58 ± 0.15 mg L-1).

Advances in fabrication of molecularly imprinted electrochemical sensors for detection of contaminants and toxicants

Worldwide growing concerns about water contamination and pollution have increased significant interest in trace level sensing of variety of contaminants. Thus, there is demand for fabrication of low cost, miniaturized sensing device for in-situ detection of contaminants from the complex environmental matrices capable of providing selective and sensitive detection. Molecularly imprinted polymers (MIPs) has portrayed a substantial potential for selective recognition of various toxicants from a variety of environmental matrices, thus widely used as artificial recognition element in the electrochemical sensors (ECS) owing to their chemical stability, easy and low cost synthesis. The combination of nanomaterials modifiers with MIPs has endowed MIP-ECS with significantly improved sensing performance in the recent years, as the nanomaterial provide properties such as increased surface area, increased conductivity and electrocatalytic activity with enhanced electron transport phenomena, whereas MIPs provide selective recognition effect.In the present review, we have summarized the advances of MIP-ECS electrochemical sensors reported in last six years (2017–2022) for sensing of variety of contaminates including drugs, metal ions, hormones and emerging contaminates. Scope of computational modelling in design of sensitive and selective MIP-ECS is reviewed. We have focused particularly on the synthetic protocols for MIPs preparation including bulk, precipitation, electropolymerization, sol-gel and magnetic MIPs. Moreover, use of various nanomaterial as modifiers and sensitizers and their effects on the sensing performance of resulting MIP-ECS is described. Finally, the potential challenges and future prospects in the research area of MIP-ECS have been discussed.

Novel Magnetic Molecularly Imprinted Polymer (MMIP) Based on a Magnesium-Aluminum Layered Double Hydroxide for the Selective Dispersive Micro-Solid-Phase Extraction (SPE) of Fenitrothion with Analysis by Ion Mobility Spectrometry

A novel magnetic molecularly imprinted polymer (MMIP) based on magnesium-aluminum layered double hydroxide was synthesized and employed for the selective dispersive micro-solid phase extraction of fenitrothion prior to its determination using ion mobility spectrometry. The characterization of the prepared MMIP was performed using x-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, vibrating sample magnetometry, and field emission scanning electron microscopy (FE-SEM). The adsorption capacity of magnetic layered double hydroxide modified with molecularly imprinted polymer (mag-LDH@MIP) was 24.0 mg g−1. The factors affecting extraction efficiency were optimized. Using the optimized conditions, the developed method provided favorable linearity (5.0–200.0 μg L−1), a low limit of detection (1.1 μg L−1), and a high preconcentration factor (67). The values for the intra- and inter-day relative standard deviation (n = 5) for fenitrothion were 3.3 and 4.5%, respectively. This developed method was successfully employed to determine trace quantities of fenitrothion in food and water.

Magnetic molecularly imprinted polymers for selectively adsorbing flavins and their effects on bioremoval of Acid Red 18 and Cr(VI)

AbstractBACKGROUNDFlavins can be used as redox mediators to accelerate anaerobic biotransformation of refractory pollutants. For better application of flavins, suitable immobilization methods need to be developed. As most microorganisms can synthesize flavins, it is a good strategy to develop selective solid sorbents for immobilizing the flavins released by waste biomass including waste activated sludge (WAS).RESULTSNovel core–shell magnetic molecularly imprinted polymers (MMIPs) for flavins were successfully prepared. The adsorption amount of 10 mg of MMIPs for flavin mononucleotide (FMN) could reach 29.19 μmol g−1, which was around 24.9‐fold higher than that of magnetic non‐molecularly imprinted polymers (1.17 μmol g−1). Their isothermal adsorption process followed the Langmuir model. Similar adsorption behaviors of MMIPs were also observed for flavin adenine dinucleotide (FAD) and riboflavin. The three flavins adsorbed on MMIPs enhanced the removal rates of azo dye Acid Red 18 (AR 18) and Cr(VI) by Shewanella oneidensis MR‐1. Moreover, the catalytic performance of MMIPs–FMN could remain at 97.6% of the original value after five repeated usages. Further studies found that MMIPs could efficiently adsorb FAD from the lysate of WAS, and MMIPs–FAD enhanced the decolorization of AR 18.CONCLUSIONSThe novel MMIPs could selectively adsorb flavins. MMIPs–flavins exhibited good catalytic and repeated usage performances, indicating that they could be used for accelerating anaerobic biotransformation of refractory pollutants. © 2022 Society of Chemical Industry (SCI).

Core-shell magnetic molecularly imprinted polymer for selective recognition and detection of sunset yellow in aqueous environment and real samples

Magnetic Molecularly imprinted polymers (MMIPs) have been recently recognized as an exceptional tool for monitoring and decontamination of environmental and biological samples of diverse nature. Based on the potential applications as sorbents and biomimetic sensors, herein, a core-shell magnetic-molecularly imprinted polymer (MMIP) was developed as a selective material for separation and sensing of sunset yellow (SY) dye in an aqueous environment and real samples. The MMIP was synthesized via precipitation polymerization using SY as a template, MAA as a functional monomer (chosen based on simulation studies), EGDMA as a cross-linking agent, and AIBN as an initiator. To elaborate the specificity of MMIP, a comparative agent, magnetic non-imprinted polymer (MNIP) was also synthesized. The XRD results showed that the MMIP showed both crystalline and amorphous structure attributed to the presence and polymeric and non-polymeric groups. The FTIR spectra confirmed synthesis of intermediate and final MMIP product. The SEM results showed spherical morphology and porous structure of the MMIP with an average particle size of 0.636 μm in diameter. The MMIP was first employed as a sorbent for the removal of SY from the aqueous environment. The binding experiments performed at optimized operating conditions (pH 2; time 30 min; sorbent dosage 3 mg; sorbate concentration 80 ppm) showed more selectivity when compared with MNIP. The data fitted best to Langmuir's sorption isotherm (Qo 359.8 mg/g) and followed the pseudo-second-order kinetic model. The synthesized MMIP was also used as an electrochemical sensor for detection of SY dye in the aqueous environment, which exhibited a linear range of detection as (1.51 × 10−6 – 1.5 × 10−3 M). The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.00413 M and 0.0137 M, respectively. While the R2 value was found to be 0.997 at optimized analytical conditions. These results suggested that the synthesized MMIP can be applied for the selective separation and quantification of SY dye in sample of diverse nature.