Molecularly imprinted polymers with novel functional monomer for selective solid-phase extraction of gastrodin from the aqueous extract of Gastrodia elata

A biobased magnetic dual-dummy-template molecularly imprinted polymer using a deep eutectic solvent as a coporogen for highly selective enrichment of organophosphates

An eco-friendly magnetic dual-dummy-template molecularly imprinted polymer (MDDMIP) was prepared by a "one-pot" green synthesis using mixed-valence iron hydroxide as the magnetic material, a deep eutectic solvent as the coporogen, and caffeic acid and glutamic acid as binary monomers. The adsorption properties toward organophosphorus pesticides (OPPs) were investigated. High adsorption capacities (269.65-304.93 mg g^-1), quick adsorption times (20 s), and high imprinting factors (2.28-3.83) were obtained. The proposed MDDMIP was utilized for magnetic solid phase extraction (MSPE) of OPPs prior to quantification by high performance liquid chromatography (HPLC). The developed method exhibited outstanding linearity (0.05-500 μg L^-1), low detection limits (0.003-0.015 μg L^-1), and excellent enrichment factors (940-1310 folds). The MSPE-HPLC method was successfully applied for the detection of OPPs in vegetable, fruit, and grain samples with acceptable recoveries (80-119%). This method is a good potential method for the analysis of pesticide residues in complex matrices.

Hydroxyl-riched covalent organic framework for solid-phase microextraction of flavonoids aglycones or their metabolites in mice's plasma: Luteolin and quercetagetin as examples

Herein, a hydroxyl‑riched covalent organic framework (named COF-DES-1) was synthesized using 1,3,5-tris(4-aminophenyl)benzene and 2,5-dihydroxyterephthalaldehyde as building blocks and employed as a coating of solid-phase microextraction (SPME) fiber. Ascribed to the advantages (e.g. suitable pore size and rich functional group characteristics) of coating, the SPME fiber showed good adsorption capacities to flavonoids aglycones including luteolin and quercetagetin, and the maximum adsorption capacities for them were 145.31 µg and 84.75 µg, respectively. Due to the size exclusion property of COF-DES-1, SPME fiber showed good protein exclusion effects on seven selected proteins with high exclusion efficiencies (>93%). Accordingly, an attractive strategy of the combination of COF-DES-1 based SPME fiber and HPLC-MS/MS was proposed for the extraction and determination of luteolin, quercetagetin or their metabolites. The results revealed that the fiber can be effectively applied to extract luteolin and its metabolites, and quercetagetin from mice's palsma. Compared with the traditional protein precipitation methods, the extraction effects of SPME fiber based extraction method were much better, indicating the promising applicability of the fiber for the enrichment of flavonoids aglycones or their metabolites in biological samples.

Expression and existence forms of mast cell activating molecules and their antibodies in systemic lupus erythematosus

INTRODUCTION

Mast cells are regarded as a kind of classical anaphylaxis cells. However autoimmune diseases and allergic reactions have many similarities or overlaps. A large number of papers have proved that mast cells play a significant role in the pathogenesis of systemic lupus erythematosus (SLE). It is speculated that IgE, anti-IgE antibodies, FcεRI, and anti-FcεRI antibodies activate mast cells through autoimmune pathways and participate in the disease process of SLE. Naturally occurring protein molecules not only exist in monomer form, but also in polymer of protein molecules. Therefore, whether IgE, FcεRIα, anti-IgE antibodies, and anti-FcεRI antibodies also exist in polymeric forms in the natural state is worthy of further investigation.

METHODS

The serum samples and clinical data of 131 patients with SLE were collected from Qilu Hospital (Qingdao). Sixty healthy individuals were collected as the control group. Serum FcεRIα, anti-IgE, and anti-FcεRI were detected by enzyme-linked immunosorbent assay. Serum IgE was detected by rate scatter nephelometry. A Chinese hamster ovarian cancer cell line CHO3D10 transfected with human FcεRIα was cultured and the cell protein extract was prepared. The existence forms of FcεRIα in the cell protein extract were detected by the native-page method.

RESULTS

The serum FcεRIα in SLE patients was significantly higher than that in control group (3.52 [2.18, 4.71] µg/ml and 1.87 [1.52, 2.33] µg/ml, respectively; p < .05). Anti-IgE was significantly lower than that in the control group (0.85 [0.55, 1.21] µg/ml and 1.23 [0.95, 1.58] µg/ml, respectively; p < .05). The CHO3D10 cell line expressed the FcεRIα, which had one kind of monomer (mFcεRIα) and two kinds of polymers (pFcεRIα) in the degeneration conditions.

CONCLUSION

In patients with SLE, the expression of FcεRIα was increased and the level of anti-IgE was decreased. FcεRIα had one kind of monomer and two kinds of polymers. Mast cell-associated FcεRIα involved in the inflammatory lesion of SLE.

Optimising factors affecting solid phase extraction performances of molecular imprinted polymer as recent sample preparation technique

Molecular imprinted solid-phase extraction is the technique that uses molecular imprinted polymer as the sorbent in solid phase extraction. Molecular imprinted solid-phase extraction is effective and efficient for the extraction process and cleaning as compared with solid phase extraction (SPE) without molecular imprinted polymer. The complexity of variables in molecular imprinted solid-phase extraction arise as problems in the analysis, therefore it is necessary to optimize the extraction conditions of molecular imprinted solid-phase extraction. To achieve the sorption equilibrium and achieve the shortest time, certain parameters such as contact time, ion strength of sample, pH of sample, amount of sorbent, sample flow rate, addition of salt and buffer solution, washing solvent, elution solvent, and loading solvent need to be optimized. The selection of suitable properties and quantities of each factor greatly affect the formation of appropriate interactions between the sorbent and analytes. Percentage recovery is also influenced by formation of the appropriate bonds, sample flow rates, extraction time, salt addition, and sorbent mass. Therefore, in the future, molecular imprinted solid-phase extraction optimization has to consider and adjust various factors reviewed in this paper to form appropriate interactions between the absorbent and target molecules which have an impact on the optimal results.

Preparation of Chitosan Molecularly Imprinted Polymers and the Recognition Mechanism for Adsorption of Alpha-Lipoic Acid

Two effective molecularly imprinted polymers for the adsorption of alpha-lipoic acid (ALA) were synthesized by the cross-linking of chitosan with epichlorohydrin (ECH) and glutaraldehyde (GLU), respectively, in the presence of ALA as template molecules. Investigations on the molar ratios of ALA and chitosan (–NH₂) in the preparation of chitosan molecularly imprinted polymers (MIPs) were carried out with a factor of ALA rebinding capabilities. The surface morphology and chemical properties of the polymers were characterized. The optimized MIPs crosslinked by ECH (MIPs–ECH) and MIPs crosslinked by GLU (MIPs–GLU) had adsorption capabilities of 12.09 mg/g and 19.72 mg/g for ALA, respectively. The adsorption behaviors of two kinds of chitosan MIPs including adsorption kinetics and isotherms were investigated in detail. Adsorption and kinetic binding experiments showed that the prepared MIPs–ECH and MIPs–GLU had selective adsorption and excellent affinity for ALA. In addition, the possible binding models between ALA and chitosan oligosaccharide were predicted by molecular dynamics simulation.

Solid-phase extraction of chlorophenols in seawater using a magnetic ionic liquid molecularly imprinted polymer with incorporated silicon dioxide as a sorbent

A type of magnetic ionic liquid based molecularly imprinted polymer coated on SiO₂ (Fe₃O₄@SiO₂@IL-MIPs) was prepared with 1-vinyl-3-ethylimidazole ionic liquid as functional monomer, and 1,4-butane-3,3'-bis-1-ethylimidazole ionic liquid as cross linker, 4-Chlorophenol as template was successfully applied as a selective adsorbent for selective extraction of 5 chlorophenols in seawater samples by using the magnetic solid-phase extraction (MSPE) method. 11 types of Fe₃O₄@SiO₂@IL-MIPs were synthesized and investigated for their different compositions of functional monomer (such as [C₂min][Br], [C₂min][BF₄], [C₂min][PF₆], acrylamide, methacrylic acid and 4-vinyl pyridine) and cross-linker (such as [C₄min₂][Br], [C₄min₂][BF₄], [C₄min₂][PF₆], divinylbenzene, and ethylene glycol dimethacrylate), respectively. The [C₂min][BF₄] and [C₄min₂][PF₆] based Fe₃O₄@SiO₂@IL-MIP with the highest extraction efficiencies was applied to the optimization experiment of MSPE process (including extraction time, adsorbent mass and desorption solvents). Good linearity was obtained with correlation coefficients (R²) over 0.9990 and the relative standard deviations for the intra-day and inter-day determination were less than 3.10% with the extraction recoveries ranged from 85.0% to 98.4%. The results indicated that the proposed Fe₃O₄@SiO₂@IL-MIPs possesses great identification and adsorption properties, and could be used as a good sorbent for selective extraction of CPs in environment waters.

MOF-5(Zn)-Fe2O4 nanocomposite based magnetic solid-phase microextraction followed by HPLC-UV for efficient enrichment of colchicine in root of colchicium extracts and plasma samples

In present work, facile method is developed for determination of colchicine in human plasma sample, autumn and spring root of colchicium extracts by ultrasound assisted dispersive magnetic solid phase microextraction followed by HPLC-UV method (UAD-MSPME-HPLC-UV). Magnetic (Fe₂O₄-nanoparticles) metal organic framework-5, (MOF-5(Zn)-Fe₂O₄NPs) was synthesized by dispersing MOF-5 and Fe(NO₃)₃.9H₂O in ethylene glycol (as capping agent) and NaOH (pH adjustment agent) by hydrothermal method. The prepared sorbent was characterized via XRD and SEM analysis and applied as magnetic solid phase in UAD-MSPME-HPLC-UV method. In this method, colchicine molecules were sorbed on MOF-5(Zn)-Fe₂O₄NPs sorbent by various mechanisms like ion exchange, hydrogen bonding and electrostatic, ᴨ-ᴨ, hard-hard and dipole-ion interaction followed by exposing sonication waves as incremental mass transfer agent and then the sorbent was separated from the sample matrix by an external magnetic fields. Subsequently, accumulated colchicine were eluted by small volume of desorption organic solvent. Influence of operational variables such as MOF-5(Zn)-Fe₂O₄NPs mass, volume of extracting solvent and sonication time on response property (recovery) were studied and optimized by central composite design (CCD) combined with desirability function (DF) approach. Under optimum condition, the method has wide linear calibration rang (0.5-1700ngmL^-1) with reasonable detection limit (0.13ngmL^-1) and R²=0.9971. Finally, the UAD-MSPME-HPLC-UV method was successfully applied for determination of colchicine autumn and spring root of colchicium extracts and plasma samples.

Selective removal and preconcentration of triclosan using a water-compatible imprinted nano-magnetic chitosan particles

A water-compatible magnetic triclosan (TCS) imprinted material (TCS-CTS-Fe⁰-MIPs) was synthesized for selective enrichment and detection of TCS in real complex water samples. The material was synthesized by using chitosan (CTS) as functional monomer, which has rich surface O- and N-containing functional groups. The TCS imprinted CTS was coated on Fe⁰ surface and then cross-linked with glutaraldehyde. Scanning electron microscopy suggested that the imprinted material was covered with a layer of imprinted film, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed that the imprinted material had more functional groups (amino and hydroxyl groups) than that of non-imprinted material. The TCS imprinted and non-imprinted materials used in each adsorption experiments were 0.1 mg mL^-1. The maximum adsorption capacity of the TCS imprinted material and non-TCS imprinted material were 20.86 and 15.11 mg g^-1, respectively. The adsorption results showed that selectivity coefficient was 10.151, 1.353, and 8.271 in the presence of p-chlorophenol, 2,4,6-trichlorophenol, and bisphenol-A, respectively. The recoveries of river water and lake water samples were 92.8, 91.3, 92.4, and 81.4, 82.3, 82.1%, respectively, when the samples were spiked with 4, 6, and 8 μg L^-1 of TCS with the imprinted material. The adsorption capacity of the TCS imprinted material and non-TCS imprinted material lost 5.2 and 6.2% after six times of recycling. The high selectivity and excellent adsorption capacity of the imprinted material can be attributed to the presence of sterically complementary imprinted sites and high surface, which would also made it more accessible to TCS than that of non-imprinted material. The present study would provide an environmental friendly and convenient method for the removal and the monitoring of TCS in environmental water samples.

Evaluation of a mixed anionic-nonionic surfactant modified eggshell membrane as an advantageous adsorbent for the solid-phase extraction of Sudan I-IV as model analytes

The coadsorption of mixed anionic-nonionic surfactants, sodium dodecylbenzenesulfonate with Triton X-100, on the surface of eggshell membrane was investigated based on adsorption isotherms to improve the solid-phase extraction performance of eggshell membrane toward organic contaminants. Results showed that even though excess Triton X-100 might inhibit the adsorption of sodium dodecylbenzenesulfonate, a low dosage of Triton X-100 can significantly improve sodium dodecylbenzenesulfonate modification and enhance the extraction efficiency of eggshell membrane from 73.7 to 100.4% because of the formation of mixed hemimicelles. The highest recovery was achieved at 2:8 (Triton X-100/sodium dodecylbenzenesulfonate mass ratios), and multiple mechanisms involving π-π interactions, hydrophobic effect, and π-π electron donor-acceptor interactions contributed to the strong extraction affinity. When mixed, the Triton X-100 and sodium dodecylbenzenesulfonate modified eggshell membrane packed cartridge coupled with high-performance liquid chromatography was applied for the simultaneous determination of trace Sudan I-IV, and low detection limits (0.16-0.26 ng/L) were achieved with satisfactory linearity (R²  > 0.999) in 10-10 000 μg/L. For real samples, Sudan II and III in one chilli sauce sample were found at 4.3 and 1.7 μg/kg. Sudan I-IV recoveries at three spiked levels were 87.4-102.9% with precisions <6.8%. Comparison with commonly used solid-phase extraction adsorbents and methods further reflected the superiorities of the proposed adsorbent in sensitivity, retention ability, and applicability.

Selective solid phase extraction of chloroacetamide herbicides from environmental water samples by amphiphilic magnetic molecularly imprinted polymers

In this study, a novel amphiphilic magnetic molecularly imprinted polymers (MMIPs) have been prepared by using Fe₃O₄ microspheres as the magnetic core, 4-vinyl pyridine (4-VP) and alkenyl glycosides glucose (AGG) as functional co-monomers. Fe₃O₄ microspheres were directly encapsulated by the polymer without any surface modification in the distillation-precipitation polymerization. The morphology and composition of MMIPs were characterized by X-ray diffraction (XRD), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Binding property and magnetic separation ability were systematically investigated through the equilibrium binding experiments. The feasibility of magnetic molecular imprinted solid phase extraction (MMISPE) was investigated for the selective enrichment of chloroacetamide herbicides from environmental water samples. The developed MMISPE-HPLC method exhibited good linearity (0.1-200μgL^-1), low limit of detection (0.03-0.06μgL^-1), and good precision (RSD<7%) under the optimized conditions. The introduced MMISPE-HPLC method was successfully used to analyze chloroacetamide herbicides in environmental water samples. Spiked chloroacetamide herbicides recoveries in three water samples ranged from 82.1% to 102.9%. These results indicated that amphiphilic MMIPs were the promising sorbents for the selective enrichment of chloroacetamide herbicides at trace levels from real environmental water samples.

Molecularly Imprinted Polymers for Selective Extraction of Oblongifolin C from Garcinia yunnanensis Hu

Molecularly imprinted polymers (MIPs) were synthesized and applied for the selective extraction of oblongifolin C (OC) from fruit extracts of Garcinia yunnanensis Hu. A series of experiments and computational approaches were employed to improve the efficiency of screening for optimal MIP systems in the study. The molar ratio (1:4) was eventually chosen based on the comparison of the binding energy of the complexes between the template (OC) and the functional monomers using density functional theory (DFT) at the RI-PBE-D3-gCP/def2-TZVP level of theory. The binding characterization and the molecular recognition mechanism of MIPs were further explained using the molecular modeling method along with NMR and IR spectra data. The reusability of this approach was demonstrated in over 20 batch rebinding experiments. A mass of 140.5 mg of OC (>95% purity) was obtained from the 5 g extracts, with 2 g of MIPs with the best binding properties, through a gradient elution program from 35% to 70% methanol-water solution. At the same time, another structural analog, 46.5 mg of guttiferone K (GK) (>88% purity), was also obtained by the gradient elution procedure. Our results showed that the structural analogs could be separated from the crude extracts by the molecularly imprinted solid-phase extraction (MISPE) using a gradient elution procedure for the first time.

Development of hydrophilic magnetic molecularly imprinted polymers by directly coating onto Fe3O4 with a water-miscible functional monomer and application in a solid-phase extraction procedure for iridoid glycosides

Development of hydrophilic magnetic molecularly imprinted polymers by directly coating onto Fe₃O₄ with a water-miscible functional monomer and application in a solid-phase extraction procedure for iridoid glycosides.

Water-compatible molecularly imprinted polymers for selective solid phase extraction of dencichine from the aqueous extract of Panax notoginseng

Specific molecularly imprinted polymers for dencichine were developed for the first time in this study by the bulk polymerization using phenylpyruvic acid and dl-tyrosine as multi-templates. The photographs confirmed that molecularly imprinted polymers prepared using N,N'-methylene diacrylamide as cross-linker and glycol dimethyl ether as porogen displayed excellent hydrophilicity. Selectivity, adsorption isotherm and adsorption kinetics were investigated. The sample loading-washing-eluting solvent was optimized to evaluate the property of molecularly imprinted solid phase extract. Compared with LC/WCX-SPE, water-compatible molecularly imprinted solid phase extraction displayed more excellent specific adsorption performance. The extracted dencichine from Panax notoginseng with the purity of 98.5% and the average recovery of 85.6% (n=3) was obtained.

Superhydrophilic molecularly imprinted polymers based on a water-soluble functional monomer for the recognition of gastrodin in water media

In this study, the first successfully developed superhydrophilic molecularly imprinted polymers (MIPs) for gastrodin recognition have been described. MIPs were prepared via the bulk polymerization process in an aqueous solution using alkenyl glycosides glucose (AGG) as the water-soluble functional monomer. The non-imprinted polymers (NIPs) were also synthesized using the same method without the use of the template. The dynamic water contact angles and photographs of the dispersion properties confirmed that the molecularly imprinted polymers displayed excellent superhydrophilicity. The results demonstrated that the MIPs exhibited high selectivity and an excellent imprinting effect. A molecularly imprinted solid phase extraction (MISPE) method was established. Optimization of various parameters affecting MISPE was investigated. Under the optimized conditions, a wide linear range (0.001-100.0μgmL(-1)) and low limits of detection (LOD) and quantification (LOQ) (0.03 and 0.09ngmL(-1), respectively) were achieved. When compared with the NIPs, higher recoveries (90.5% to 97.6%) of gastrodin with lower relative standard deviations values (below 6.4%) using high performance liquid chromatography were obtained at three spiked levels in three blank samples. These results demonstrated one efficient, highly selective and environmentally-friendly MISPE technique with excellent reproducibility for the purification and pre-concentration of gastrodin from an aqueous extract of Gastrodia elata roots.

Molecularly imprinted solid phase extraction in a syringe filter for determination of triazine herbicides in Radix Paeoniae Alba by ultra-fast liquid chromatography

A novel, cost-effective and simple solid phase extraction (SPE) method, by using a syringe connected with a nylon membrane filter as the adsorbent container, was developed for the extraction of triazine herbicides from Radix Paeoniae Alba (RPA) samples. The selective molecularly imprinted polymers (MIPs) synthesized with the template of atrazine were employed as the adsorbents for the enrichment and purification of analytes. The extraction parameters, including the volume and type of loading solvent, the type of washing solvent and eluting solvent, were investigated. Under the optimized conditions, the final extracts were analyzed by ultra-fast liquid chromatography (UFLC). Recoveries of the developed method range from 92.4% to 107.3% with intra- and inter-day relative standard deviations (RSDs) lower than 8.2%. The calibration curve is linear in the concentration range of 0.005-2.4 µg g(-1) for desmetryn, atrazine and terbumeton, and 0.005-1.5 µg g(-1) for dimethametryn and dipropetryn, with the correlation coefficient (R(2)) higher than 0.9995. The limits of detection (LODs) of five triazine herbicides are in the range of 0.09-0.39 ng g(-1), which are lower than the maximum residue levels (MRLs) established by various official organizations. Analytical results of three real Radix Paeoniae Alba samples indicate that the proposed method is cost-effective and easy-to-use than other routine pretreatment methods.

Preparation and application of molecularly imprinted polymer for isolation of chicoric acid from Chicorium intybus L. medicinal plant

Molecularly imprinted polymer (MIP) was synthesized and applied for the extraction of chicoric acid from Chicory herb (Chicorium intybus L.). A computational study was developed to find a suitable template to functional monomer molar ratio for MIP preparations. The molar ratio was chosen based on the comparison of the binding energy of the complexes between the template and functional monomers. Based on the computational results, eight different polymers were prepared using chicoric acid as the template. The MIPs were synthesized in a non-covalent approach via thermal free-radical polymerization, using two different polymerization methods, bulk and suspension. Batch rebinding experiments were performed to evaluate the binding properties of the imprinted polymers. The best results were obtained with a MIP prepared using bulk polymerization with 4-vinylpyridine (4-VP) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the crosslinker with a molar ratio of 1:4:20. The best MIP showed selective binding ability toward chicoric acid in the presence of the template's structural analogues, caffeic acid, caftaric acid and chlorogenic acid.

Preparation of the high purity gingerols from ginger by dummy molecularly imprinted polymers

In this work, a dummy molecularly imprinted polymers (MIPs) were developed as the selective sorbents for preparation of the high purity gingerols from ginger for the first time. The dummy template molecule with similar structural skeleton to gingerols, N-vanillylnonanamide, has been designed and synthesized. The performance of the MIPs and non-imprinted polymers (NIPs) were evaluated including selective recognition capacity, adsorption isotherm, and adsorption kinetics. Optimization of various parameters affecting dummy molecular imprinted solid phase extraction (MISPE), such as the type and flow rate of the loading solvent, the composition and volume of the eluting solvent, and the composition and volume of the washing solvent were investigated. Gingerols with the percent recovery of 80 and the percent purity of 99.1 were obtained from the extracts of ginger by MISPE. Besides, gingerols obtained by MISPE had more powerful activity of eliminating free radical compared with extracts before extraction with the MISPE column. Application of MIPs with a high affinity toward three gingerols provides a novel method for obtaining a group of compounds which have likely active groups from natural products.

Preparation of temperature sensitive molecularly imprinted polymer coatings on nickel foam for determination of ofloxacin in Yellow River water by solid-phase microextraction

A new ofloxacin-templated MIP on nickel foam was investigated for the determination of antibiotics in river water.

Surface molecularly imprinted polymers with dummy templates for the separation of dencichine from Panax notoginseng

Surface molecularly imprinted polymers with dummy templates for the targeted separation of dencichine from Panax notoginseng.