Magnetic Molecularly Imprinted Polymers Research Articles

A magnetic SERS-imprinted sensor for the determination of cardiac troponin I based on proteolytic peptide technology

Acute myocardial infarction is a sudden and high-mortality disease that can be accurately diagnosed by measuring the level of cardiac troponin I in the blood. Currently, cTnI commonly used clinical detection methods usually have excellent sensitivity and are suitable for large-scale sample detection analysis. However, most of these methods are operated through multiple steps of fixation, incubation, reaction and separation, and most of them require professionals to operate complex instruments, which greatly limits their applicability in real-time rapid detection. Therefore, a method that requires low professional skills and can perform rapid detection is necessary. We presents an alternative strategy to quantify cTnI in clinical serum samples using a combination of SERS and magnetic molecularly imprinted polymers (MMIP). MMIPs was synthesized under Polyvinyl Pyrrolidone (PVP) conditions without vinyl modification using characteristic peptide as template, MAA and DMAm as functional monomers. The internal Raman probe 4-MBA was connected through Ag-SH bonds in MMIPs to solve the problem that the target object had no Raman characteristic peak. MMIPs with high magnetic and adsorptive properties showed characteristic absorption peaks at the Raman shift of 1582 cm−1 after specific capture of the target templates. The Raman signals of the 4-MBA were reduced due to shielding effects and the detection range of this method was 0.001–100 ng mL−1. The recoveries and relative standard deviations (RSDs) of the spiked experiments were 103.1%–106.3 % and 3.54 %–7.38 %, respectively. In summary, this work had appropriate sensitivity and specificity, and there was no significant difference in detection results after ELISA verification. It provided a flexible and practical analysis method for detecting cTnI based on SERS technology. In addition, the imprinting materials of other disease markers can be prepared by changing the template molecules, which provides a new idea for the detection of other biomarkers.

Synthesis and characterization of core-shell magnetic molecularly imprinted polymer nanocomposites for the detection of interleukin-6.

Interleukin-6 (IL-6) belongs to the cytokine family and plays a vital role in regulating immune response, bone maintenance, body temperature adjustment, and cell growth. The overexpression of IL-6 can indicate various health complications, such as anastomotic leakage, cancer, and chronic diseases. Therefore, the availability of highly sensitive and specific biosensing platforms for IL-6 detection is critical. In this study, for the first time, epitope-mediated IL-6-specific magnetic molecularly imprinted core-shell structures with fluorescent properties were synthesized using a three-step protocol, namely, magnetic nanoparticle functionalization, polymerization, and template removal following thorough optimization studies. The magnetic molecularly imprinted polymers (MMIPs) were characterized using dynamic and electrophoretic light scattering (DLS and ELS), revealing a hydrodynamic size of 169.9 nm and zeta potential of +17.1 mV, while Fourier transform infrared (FTIR) spectroscopy and fluorescence spectroscopy techniques showed characteristic peaks of the polymer and fluorescent tag, respectively. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) investigations confirmed the successful encapsulation of the magnetic core within the ca. 5-nm-thick polymeric shell. The MMIP-based electrochemical sensing platform achieved a limit of detection of 0.38 pM within a linear detection range of 0.38-380 pM, indicating high affinity (dissociation constant KD = 1.6 pM) for IL-6 protein in 50% diluted serum samples. Moreover, comparative investigations with the non-imprinted control polymer demonstrated an imprinting factor of 4, confirming high selectivity. With multifunctional features, including fluorescence, magnetic properties, and target responsiveness, the synthesized MMIPs hold significant potential for application in various sensor techniques as well as imaging.

"Explosive" CaCO3 microcapsules driven by EDTA combined with a "signal booster" semiconductor Zn0.995Ce0.005O SERS substrate for ultra-sensitive SERS detection of chloramphenicol

BackgroundChloramphenicol (CAP) is a broad-spectrum antibiotic, and its continuous use in human medicine, livestock has resulted disturbances in ecosystem stability. The complex background and low concentration of CAP in aquatic environments present significant scientific challenges for its sensitive detection. Currently detection techniques such as high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) are hindered by their complex procedures and high costs. Surface-enhanced Raman spectroscopy (SERS), due to its unique ability for fingerprint recognition, has emerged as a powerful tool for analysis and detection. However, it is often limited by the low kurtosis expression of the target. ResultThe water-soluble explosive polyethylenimide grafted calcium carbonate (PEI@CaCO3) microcapsule was utilized to encapsulate the signal probe Ag@4-NTP and combine it with a semiconductor SERS substrate Zn0.995Ce0.005O, enabling ultra-sensitive detection of CAP through a signal attenuation strategy. Moreover, magnetic molecularly imprinted polymers (MMIP) and nucleic acid aptamers were employed as capture probes for achieving rapid and direct magnetic separation, followed by layer-by-layer assembly to construct the sensor probe. In the presence of CAP, the aptamers and rMMIPs selectively recognized the target, forming a PEI@CaCO3@Ag@4-NTP@Apt@CAP@rMMIPs "sandwich" structure (Microcapsule@Apt@rMMIPs). After multiple magnetic separations, the "igniter" EDTA solution was added, causing the CaCO3 capsules to rapidly "explode" and release a significant amount of Ag@4-NTP. This was then applied to the "signal booster" semiconductor SERS substrate. Under optimal conditions, this method exhibited a detection range of 1.0 × 10−5 M to 1.0 × 10−15 M, with a detection limit of 6.84 × 10−16 M. SignificantThe unite of magnetic MIP and nucleic acid aptamer to form a “sandwich” structure, in combination with a semiconductor SERS substrate, not only enhances the sensor's sensitivity but also offers significant economic advantages. Moreover, this innovative technology holds great promise for accurate and highly sensitive detection of pollutants in complex environments.

Selective extraction of Quercetin from rose petal extracts using poly (acrylamide-co-ethylene glycol dimethylacrylate) based magnetic molecularly imprinted polymer

Under ultrasound irradiation, a highly selective Magnetic Molecularly Imprinted Polymer (MMIP) was synthesized by polymerizing monomers on magnetite. The Density Functional Theory was utilized for the selection of suitable monomers based on binding energy interaction between quercetin and monomers (Acrylamide, Acrylonitrile, Methacrylic Acid). Quercetin served as the template molecule, while acrylamide was used as the functional monomer, and a mixture of DMSO and water was employed as the porogen solvent. This study aims to synthesize and evaluate the effectiveness of MMIP and analyze its adsorption isotherm and kinetics. It was observed that the Freundlich model supports the adsorption of quercetin on MMIP, and the kinetic data correlates better with the Pseudo-first-order kinetic model. The MMIP exhibited a pronounced selectivity in the adsorption of quercetin with a maximum adsorption capacity of 10.07 mg g-1 in 30 min. Furthermore, the physiochemical properties of synthesized sorbent were undergone for characterization using FESEM, EDX, XRD, FTIR, VSM, and TGA. Finally, real-time determination of quercetin was carried out using rose petal extract, integrating MMIP adsorption followed by HPLC detection. The results suggest that MMIP is a promising material for the real-time determination of quercetin from rose petal extract.

Magnetic particle spray mass spectrometry for the determinationof beta-blockers in plasma samples.

Magnetic particle spray mass spectrometry (MPS-MS), an innovative ambient ionization technique proposed by our research group, was employed to determine beta-blockers in human plasma samples. A dispersive solid phase extraction of atenolol, metoprolol, labetalol, propranolol, nadolol, and pindolol was carried out using magnetic molecularly imprinted polymer (M-MIP) particles that were attached to the tip of a metal probe, which was placed in the mass spectrometer inlet. A solvent (1% formic acid in methanol) was dispensed on the particles, and the Taylor cone was formed around them (in high voltage). The analytes were desorbed/ionized and determinedby a triple quadrupole mass spectrometer. M-MIP was synthesized with oxprenolol as a pseudo-template, demonstrating good selectivity to beta-blockers compared withno-analog molecules, with an adsorption process occurring in monolayers, according to isotherm studies. Kinetic experiments indicated chemisorption as the predominant M-MIP/analyte interaction. The analytical curves were linear (R2 > 0.98), and the limit of quantification was 3µg L-1 for all the analytes. Limits of detection ranged from 0.64 to 2.41µg L-1. Precisions (relative standard deviation) and accuracies (relative error) ranged from 3.95 to 21.20% and-17.05 to 18.93%, respectively. MPS-MS proved to be a simple, sensitive, and advantageous technique comparedwithconventional approaches. The analyses were fast, requiring no chromatographic separation and without ionic suppression. The method is aligned with green chemistry principles, requiring minimal sample, solvent, and sorbent amounts. MPS-MS successfully integrates sample preparation and ambient ionization mass spectrometry and holds great potential for application with other sorbents, samples, and analytes.

Preparation of core-shell magnetic molecularly imprinted polymers on Fe3O4 nanosphere via self-polycondensation for magnetic solid-phase extraction of 2,4-dinitrophenol in environmental water samples

ABSTRACT In this study, a core-shell magnetic molecularly imprinted polymers (MMIPs) adsorbent targeting 2,4-dinitrophenol (2,4-DNP) as a template molecule was developed by surface polymerisation and applied for magnetic solid-phase extraction prior to the determination of 2,4-DNP in environmental water samples via high-performance liquid chromatography. Different experiments were carried out to optimise the magnetic solid-phase extraction conditions. Subsequently, the adsorption capacity and selectivity of prepared MMIPs were investigated. Theoretical analysis demonstrated that the experimental data fitted well to the pseudo-second-order model, suggesting that chemical adsorption might be the rate-limiting step, with a maximum adsorption capacity of 21.76 mg g−1. Under the optimised conditions, this method showed relatively wide linearity within the concentration range of 0.0025 μg·mL−1−0.5 μg·mL−1, with a relative standard deviation of 2.5%–6.2%. The detection limit and quantification limit were 0.23 µg·L−1 and 0.76 µg·L−1, respectively.

Selective solid phase extraction of folic acid from tomato as a biological source with a magnetic molecularly imprinted polymer measured by fluorescence spectroscopy

AbstractA novel magnetic molecular-imprinted polymer (MMIP) was used to selectively extract folic acid directly from real samples. Folic acid was used as template molecule, Fe3O4/SiO2-3-triethoxysilyl-propyl-acrylamide as functional monomer, azobisisobutyronitrile as initiation, ethylene glycol dimethacrylate as crosslinker agent, and acrylamide as the secondary monomer in a mixed ethanol-water solvent. The effect of different parameters on the extraction efficiency was studied, and the optimum conditions were established as follows: the concentrations of crosslinking and template were fixed at 0.05 and 0.06 g, absorption percentage was 96.5, pH was adjusted to 8, and extraction time was 8 h with a temperature of 25 °C. By examining the effect of pH, we tried to investigate the effect of the amide groups that present in MMIP and its intermolecular hydrogen interaction with folic acid. After optimising the effective parameters in polymer synthesis and adsorption rate, a magnetic imprinting dispersive solid-phase extraction method combined with fluorescence spectrophotometry at λem = 367 nm (MMIP-DSPE-FL) was constructed for sensitive determination of folic acid in tomato samples. The limit of quantification (LOQ) and limit of detection (LOD) values were 30.00 ± 0.01 μg L−1 and 10.00 ± 0.03 μg L−1, respectively, after the MMIP-DSPE preconcentration. Three tomato samples were analysed to give recoveries in the range of 80.2–81.6%, with relative standard deviation values below 0.6% (n = 3). The prepared MMIP-DSPE showed high selectivity toward folic acid, which could be used six times without changing adsorption capacity. The adsorption isotherm of the folic acid-imprinted polymer pursued the Langmuir model (RL = 0.029), and the kinetics model followed pseudo-first-order (R2 = 0.9974).

Highly selective magnetic molecularly imprinted polymer for preconcentration and determination of atorvastatin in human urine samples

To determine the presence of atorvastatin (AT) in urine samples, a cost-effective and environmentally responsible technique has been developed combining magnetic molecularly imprinted polymer-based dispersive solid-phase microextraction and HPLC with UV detection. FESEM and TEM have been used to appropriately produce and analyze a magnetic molecularly imprinted polymer (MMIP), which has shown good selectivity and a high absorption capacity. Central composite design (CCD) optimized the factors influencing the suggested method’s extraction performance. The outcomes indicated that the proposed approach had a strong correlation (R2 > 0.99) within the linear range of 0.5–900 ng mL−1. With a high enrichment factor, the LOD and LOQ were 0.15 and 0.5 ng mL−1, respectively. For inter-day and intra-day experiments, the precisions expressed in terms of relative standard deviations were 2.51 % and 1.94 %, respectively. Urine samples were examined to evaluate the effectiveness of the suggested method, and extraction recoveries ranging from 90.5-97.7 % were found. These outcomes demonstrated how well the approach performed while analyzing AT in actual samples.

Synthesis of green magnetic molecularly imprinted polymers for selective extraction of rifaximin in milk samples

In this study, a new analytical method was developed using magnetic molecularly imprinted polymers (MMIPs) by employing eco-friendly supramolecular ternary deep eutectic solvents to synthesize these MMIPs for selective extraction of rifaximin. The characterization analysis and adsorption affinity investigation were conducted. The results showed fast adsorption (15 min) with high adsorption capacity (43.20 mg g−1) and selectivity for rifaximin. Various extraction parameters were optimized, achieving recoveries ranging from 86.67% to 99.47% in spiked milk samples using high-performance liquid chromatography (HPLC). The detection and quantification limits were 0.01 mg L−1 and 0.03 mg L−1, respectively. The method exhibited low RSDs (<4.70%) and excellent selectivity, with MMIPs reusable up to seven times with only a 10% performance loss. This study proposes a convenient and reliable method for trace-level rifaximin extraction from milk using eco-friendly MMIPs.

Implementing magnetic molecularly imprinted solid phase extraction to analytical method for determination of 2-phenethylamine in cocoa powder and chocolate by LC-MS/MS system

The main aim of this study was to design, develop, and apply magnetic molecularly imprinted polymer (MMIP) during sample pretreatment before liquid chromatography tandem mass spectrometry (LC-MS/MS) 2-phenylethylamine determination in cocoa powder and chocolate samples. The morphology and structure of MMIP, obtained from methacrylic acid (monomer) and trimethylolpropane trimethacrylate (cross-linker) were characterized using scanning electron microscopy, nitrogen sorption analyses, infra-red spectroscopy, X-ray diffraction measurements, vibrating-sample magnetometry, and thermogravimetry analyses. The analyte adsorption mechanism on MMIP was studied using computational simulation. The magnetic solid phase extraction procedure on MMIP was optimized, resulting in a relative matrix effect of 6.2 % for cocoa powder and 2.8 % for chocolate. The LC-MS/MS quantified the 2-phenethylamine in eighteen cocoa powder and chocolate samples, showing a concentration range between 2.4 and 8.7 μg g−1.

Advancements and greenification potential of magnetic molecularly imprinted polymers for chromatographic analysis of veterinary drug residues in milk.

Milk, as a widely consumed nutrient-rich food, is crucial for bone health, growth, and overall nutrition. The persistent application of veterinary drugs for controlling diseases and heightening milk yield has imparted substantial repercussions on human health and environmental ecosystems. Due to the high demand, fresh consumption, complex composition of milk, and the potential adverse impacts of drug residues, advanced greener analytical methods are necessitated. Among them, functional materials-based analytical methods attract wide concerns. The magnetic molecularly imprinted polymers (MMIPs), as a kind of typical functional material, possess excellent greenification characteristics and potencies, and they are easily integrated into various detection technologies, which have offered green approaches toward analytes such as veterinary drugs in milk. Despite their increasing applications and great potential, MMIPs' use in dairy matrices remains underexplored, especially regarding ecological sustainability. This work reviews recent advances in MMIPs' synthesis and application as efficient sorbents for veterinary drug extraction in milk followed by chromatographic analysis. The uniqueness and effectiveness of MMIPs in real milk samples are evaluated, current limitations are addressed, and greenification opportunities are proposed. MMIPs show promise in revolutionizing green analytical procedures for veterinary drug detection, aligning with the environmental goals of modern food production systems.

Synthesis and characterization of magnetic molecularly imprinted polymers for the rapid and selective determination of clofazimine in blood plasma samples

Clofazimine (CLF) is a riminophenazine derivative and a new therapeutic option with high efficacy for patients with rifampicin-resistant tuberculosis (TB). The blood levels of CLF are low and suboptimal, so therapeutic drug monitoring is required. Prior to this study, there were no molecular imprinting–based solid phase extraction (SPE) sorbents that could be used to determine the blood CLF levels. Hence, we prepared a magnetic molecularly imprinted polymer (MMIPs) to capture CLF. We employed computational selection of a functional monomer and crosslinker and confirmed these selections based on the association constant (Ka) and a Job plot. We synthesised MMIPs with two surface modifiers and characterized the polymers. Our computational analysis based on the bond energy revealed that methyl methacrylate (MMA) was the most suitable functional monomer at a CLF-to-MMA molar ratio of 1:4. Based on the bond energy, the most suitable crosslinker was trimethylolpropane trimethacrylate (TRIM) at a CLF-to-TRIM molar ratio of 1:1. We determined the Ka of MMA and TRIM in different solvents. Isopropanol produced the highest Ka. The Job plot showed that a template-to-MMA-to-TRIM molar ratio of 1:4:20 was optimal to synthesize imprinted polymer in isopropanol. We prepared MMIPs using two different modifiers, namely aminopropyltrimethoxysilane (APTES) and oleic acid (OA), using the ratio determined from the Job plot. Physical characteristic tests carried out using FT-IR, SEM-EDS, PSA, BET and VSM, showed that the synthesis was success with a spherical and uniform agglomeration of particles, also a flat surface with many holes with a particle size of MMIP-APTES and MMIP-OA respectively 0.14 μm and 0.28 μm, showed a surface area for MMIP-APTES is 2874.51 m2/g and MMIP-OA 2913.07 m2/g, exhibiting superparamagnetic properties with a saturation magnetization value of MMIP-APTES 21.1 emu/g−1 and MMIP-OA 49.9 emu/g−1. Adsorption capacity result showed that MMIP-OA fits well with the Langmuir model, while MMIP-APTES fits better with the Freundlich. Application of MMIP-SPE (Magnetic Molecular Imprinted Polymer-Solid Phase Extraction) APTES resulted 92.3 ± 6.1 % and MMIP-SPE-OA 51.5 ± 8.1 % for recovering CLF in blood. The result of selectivity test also showed that MMIP-SPE-APTES is better than MMIP-SPE-OA and selectively recover CLF from human blood plasma existed together with other TB-Drugs. The study result shows that MMIPs with APTES modification can be used for CLF determination in human blood plasma.

Fabrication of magnetic hydrophilic imprinted polymers via two-step immobilization approach for targeted detecting bisphenol A

Molecularly imprinted polymer with water-compatibility for effective separation and enrichment of targeted trace pollutants from complicated matrix has captured extensive attention in terms of their high selectivity and matrix compatibility. This study focuses on modified β-cyclodextrin is used as a hydrophilic functional monomer to develop magnetic molecularly imprinted polymers (MMIPs). MMIPs were prepared using Fe3O4 nanoparticles as carriers and bisphenol A (BPA) as templates using a two-step fixation strategy and surface imprinting technology. The structural characteristic and binding properties of the prepared MMIPs were thoroughly studied. The MMIPs exhibited high crystallinity, high adsorption capacity, fast rebinding rate, remarkable selectivity and distinguish reusability. In addition, through magnetic solid-phase extraction separation technology and high-performance liquid chromatography ultraviolet quantitative detection technology, MMIPs are used for selective enrichment and detection of BPA in complex media such as environmental water and milk. This work provides a new route to construct the hydrophilic molecularly imprinted materials and a new sight on developing more effective sample pretreatment strategies for monitoring targeted pollution in complicated aqueous media.

A magnetic imprinted polymer nano-adsorbent with embedded quantum dots and mesoporous carbon for the microextraction of triazine herbicides

A magnetic molecularly imprinted polymer (MMIP) adsorbent incorporating amino-functionalized magnetite nanoparticles, nitrogen-doped graphene quantum dots and mesoporous carbon (MIP@MPC@N-GQDs@Fe3O4NH2) was fabricated to extract triazine herbicides from fruit juice. The embedded magnetite nanoparticles simplified the isolation of the adsorbent from the sample solution. The N-GQDs and MPC enhanced adsorption by affinity binding with triazines. The MIP layer provided highly specific recognition sites for the selective adsorption of three target triazines. The extracted triazines were determined by high-performance liquid chromatography (HPLC) coupled with diode-array detection (DAD). The developed method exhibited linearity from 1.5 to 100.0 µg L−1 with a detection limit of 0.5 µg L−1. Recoveries from spiked fruit juice samples were in the range of 80.1– 108.4 %, with a relative standard deviation of less than 6.0 %. The developed MMIP adsorbent demonstrated good selectivity, high extraction efficiency, ease of fabrication and use, and good stability.

Development of a simple polymer-based sensor for detection of the Pirimicarb pesticide

In this study, a sensitive and selective fluorescent chemosensor was developed for the determination of pirimicarb pesticide by adopting the surface molecular imprinting approach. The magnetic molecularly imprinted polymer (MIP) nanocomposite was prepared using pirimicarb as the template molecule, CuFe2O4 nanoparticles, and graphene quantum dots as a fluorophore (MIP-CuFe2O4/GQDs). It was then characterized using X-ray diffraction (XRD) technique, Fourier transforms infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), and transmission electron microscopy (TEM). The response surface methodology (RSM) was also employed to optimize and estimate the effective parameters of pirimicarb adsorption by this polymer. According to the experimental results, the average particle size and imprinting factor (IF) of this polymer are 53.61 nm and 2.48, respectively. Moreover, this polymer has an excellent ability to adsorb pirimicarb with a removal percentage of 99.92 at pH = 7.54, initial pirimicarb concentration = 10.17 mg/L, polymer dosage = 840 mg/L, and contact time = 6.15 min. The detection of pirimicarb was performed by fluorescence spectroscopy at a concentration range of 0–50 mg/L, and a sensitivity of 15.808 a.u/mg and a limit of detection of 1.79 mg/L were obtained. Real samples with RSD less than 2 were measured using this chemosensor. Besides, the proposed chemosensor demonstrated remarkable selectivity by checking some other insecticides with similar and different molecular structures to pirimicarb, such as diazinon, deltamethrin, and chlorpyrifos.

Magnetic molecularly imprinted polymers are used to selectively extract cephalosporins from milk samples and analyze by LC-MS/MS

Cephalosporins were extracted from milk samples by using magnetic molecularly imprinted polymers (MMIP). To characterize the physical properties of MMIP, an experiment was conducted involving both static and dynamic adsorption. Samples were analyzed with LC-MS/MS to identify cephalosporin residues. The quantitative technique employed was the use of an isotope as an internal standard. Analysis was conducted using an Ascentis C8 column with a mobile phase consisting of a 0.1 % aqueous solution of formic acid and acetonitrile. The determination coefficients varied between 0.9945 and 0.9995, as indicated by the linear equations. Cephalosporins exhibited a diverse spectrum of recovery rates, varying between 80.7 % and 118.3 %, accompanied by a range of relative standard deviations spanning from 3.8 % to 13.5 %. The detection limits for 9 kinds of cephalosporins in milk samples varied from 1 μg kg−1 to 20 μg kg−1, while the quantification limits ranged from 3 μg kg−1 to 60 μg kg−1. The successful implementation of the validated technique has been applied to detect 9 different kinds of cephalosporins in real milk products.

Molecularly Imprinted Drug Carrier for Lamotrigine-Design, Synthesis, and Characterization of Physicochemical Parameters.

This study presents the initial attempt at introducing a magnetic molecularly imprinted polymer (MIP) designed specifically for lamotrigine with the purpose of functioning as a drug carrier. First, the composition of the magnetic polymer underwent optimization based on bulk polymer adsorption studies and theoretical analyses. The magnetic MIP was synthesized from itaconic acid and ethylene glycol dimethacrylate exhibiting a drug loading capacity of 3.4 ± 0.9 μg g-1. Structural characterization was performed using powder X-ray diffraction analysis, vibrating sample magnetometry, and Fourier transform infrared spectroscopy. The resulting MIP demonstrated controlled drug released characteristics without a burst effect in the phospahe buffer saline at pH 5 and 8. These findings hold promise for the potential nasal administration of lamotrigine in future applications.

Selective adsorption of zearalenone by a novel magnetic molecularly imprinted carbon nanomaterial.

In this paper, the objective is to immobilize molecularly imprinted polymers (MIPs) onto the surface of magnetic carbon nanoparticles (Fe3O4@SiO2@C) to develop an effective method for the adsorption of zearalenone (ZEN). The prepared products were characterized by FT-IR, SEM, TEM, XRD, VSM, TGA, and BET. The content of zearalenone in corn samples was monitored by HPLC. The results indicate that the particle size of magnetic molecularly imprinted polymers (MMIPs) is approximately 200nm. The adsorption mechanism of MMIPs was confirmed by static adsorption and dynamic adsorption experiments. The maximum adsorption capacity was 1.56mg/g, and the adsorption equilibrium was reached within 50min. The scatchard model showed that MMIPs had two binding sites, a high-affinity binding site and a low-affinity site. Kinetic second-order fitting indicates that MMIPs are mainly through chemisorption. In the actual sample application, the limit of detection (LOD) and limit of quantitation (LOQ) were 0.3mg/L and 0.9mg/L, respectively. The recovery of corn with the standard addition of ZEN was 73.6-88.1%, and the relative standard deviation (RSD) was 2.86-5.63%. The results demonstrated that MMIPs possess the advantages of straightforward operation, high precision, and cost-effectiveness, rendering them suitable for rapid ZEN detection.

Preparation of surface molecularly imprinted polymers with Fe3O4/ZIF-8 as carrier for detection of Dimethoate in cabbage

In this study, molecularly imprinted polymers (MIPs) were prepared for the specific recognition of organophosphorus pesticides and a rapid, efficient and simple method was established for the detection of dimethoate (DIT) in food samples. Fe3O4 magnetic nanoparticles were synthesized by co-precipitation, and Fe3O4/ZIF-8 complexes were prepared by a modified in-situ polymerization method, and then magnetic molecularly imprinted polymers (MMIPs) were prepared and synthetic route was optimized by applying density functional theory (DFT). The morphological characterization showed that the MMIPs were coarse porous spheres with an average particle size of 50 nm. The synthesized materials are highly selective for the organophosphorus pesticide dimethoate with an adsorption capacity of 461.50 mg·g−1 and are effective resistance to matrix effects. A novel method for the determination of DIT in cabbage was developed using the prepared MMIPs in combination with HPLC. The practical results showed that the method can meet the requirements for the determination of DIT in cabbage with recoveries of 85.6–121.1 % and detection limits of 0.033 μg·kg−1.

Magnetic molecularly imprinted polymers using ternary deep eutectic solvent as novel functional monomer for hydroxytyrosol separation

In this work, magnetic molecularly imprinted polymers (MIPs) for specific recognition of Hydroxytyrosol (HT) were designed by vinyl-modified magnetic particles (Fe3O4@SiO2@VTEOs) as carrier, ternary deep eutectic solvent (DES) as functional monomer, while ethylene glycol dimethacrylate (EGDMA) as crosslinker. The optimum amount of DES was obtained by adsorption experiments (molar ratio, caffeic acid: choline chloride: formic acid = 1:6:3) which were 140 μL in total. Under the optimized amount of DES, the maximum adsorption capacity of the MIPs particles was 42.43 mg g−1, which was superior to non-imprinted polymer (4.64 mg g−1) and the imprinting factor (IF) is 9.10. Syringin and Oleuropicrin were used as two reference molecules to test the selectivity of the DES-MIPs particles. The adsorption capacity of HT was 40.11 mg g−1. Three repeated experiments show that the polymer has high stability and repeatability (RSD = 5.50).