Fabrication of a novel magnetic mesoporous molecularly imprinted polymer based on pericarpium granati-derived carrier for selective absorption of bromelain

Application of Polydopamine-Based Magnetic Solid-Phase Extraction for Highly Sensitive Determination of Aristolochic Acid I from Traditional Chinese Medicine Samples

A low cost-effective and simple synthesis method combining magnetic solid-phase extraction (MSPE) and high-pressure liquid chromatography was developed for the analysis of aristolochic acids I (AAI) in traditional Chinese medicine samples. A novel polydopamine (PDA) modified magnetic nanoparticles with one single carbon layer (Fe3O4@1C NPs) via one-pot hydrothermal approach was prepared and then successfully employed to extract AAI for the first time. Dopamine (DA) can form a PDA layer on Fe3O4@1C NPs surface through self-polymerization to form Fe3O4@1C@PDA. As a surface modifier of DA, PDA offered more adsorption sites to AAI due to π-π stacking, hydrogen bonding and electrostatic interactions. The parameters of MSPE were optimized by univariate and multivariate methods (Box-Behnken design) in detail. High degree of linearity was obtained in the range of 0.05-200.0 μg/mL. The limits of detection (S/N = 3) and quantification (S/N = 10) were 0.08 and 0.25 μg/mL, respectively. The recoveries of AAI in spiked Xiaoqinglong mixture samples were in the range of 86.7 to 108.5% with the relative standard deviation of less than 5.2%. Thus, a fast, convenient, sensitive and eco-friendly method was successfully proposed and became a promising approach for the determination of AAI in herbal plants or its preparation in the manufacturing procedure.

Computer-Aided Prediction, Synthesis, and Characterization of Magnetic Molecularly Imprinted Polymers for the Extraction and Determination of Tolfenpyrad in Lettuce

Tolfenpyrad, a pyrazolamide insecticide, can be effectively used against pests resistant to carbamate and organophosphate insecticides. In this study, a molecular imprinted polymer using tolfenpyrad as a template molecule was synthesized. The type of functional monomer and the ratio of functional monomer to template were predicted by density function theory. Magnetic molecularly imprinted polymers (MMIPs) were synthesized using 2-vinylpyridine as a functional monomer in the presence of ethylene magnetite nanoparticles at a monomer/tolfenpyrad ratio of 7:1. The successful synthesis of MMIPs is confirmed by the results of the characterization analysis by scanning electron microscopy, nitrogen adsorption-desorption isotherms, Fourier transform infrared spectroscopy, X-ray diffractometer, thermogravimetric analyzer, and vibrational sample magnetometers. A pseudo-second-order kinetic model fit the adsorption of tolfenpyrad, and the kinetic data are in good agreement with the Freundlich isothermal model. The adsorption capacity of the polymer to the target analyte was 7.20 mg/g, indicating an excellent selective extraction capability. In addition, the adsorption capacity of the MMIPs is not significantly lost after several reuses. The MMIPs showed great analytical performance in tolfenpyrad-spiked lettuce samples, with acceptable accuracy (intra- and inter-day recoveries of 90.5-98.8%) and precision (intra- and inter-day relative standard deviations of 1.4-5.2%).

Molecularly imprinted polymers as effective capturing receptors in a pseudo-ELISA immunoassay for procalcitonin detection in veterinary species

In this study, a new sandwich-type immunoenzymatic assay, based on a molecularly imprinted polymer (MIP) as an artificial antibody (pseudo-ELISA), was developed for the determination of procalcitonin (PCT) in veterinary species. The quantification of PCT in human medicine represents the state of the art for the diagnosis of sepsis; instead the clinical studies on the relevance of PCT as a sepsis predictor in veterinary patients are few, likely due to the total absence of validated assays. MIPs have been widely used as antibody mimics for important applications, and MIP-based sandwich assays have emerged as promising analytical tools for the detection of disease biomarkers. Herein, a polynorepinephrine (PNE)-based imprinted film was directly synthesized on the well surface of a 96-well plate. Subsequently, based on a commercial ELISA kit, the PCT quantification was accomplished via a colorimetric sandwich assay by replacing the capture antibody of the kit with the PNE-based MIP. This method was performed to detect canine and equine PCT in buffer and in plasma samples. Under optimal conditions, the results obtained in plasma samples showed a limit of detection (LOD) of 5.87 ng mL^-1 and a reproducibility (CV_av%) of 10.0% for canine samples, while a LOD = 4.46 ng mL^-1 and CV_av% = 7.61% were obtained for equine samples.

Recent Advances in Solid-Phase Extraction as a Platform for Sample Preparation in Biomarker Assay

Low levels of biomarkers and the complexity of bio sample make the analytical assay of several biomarkers a challenging issue. Suitable sample preparation run remain a vital part of the puzzle of diagnostic level. Enhancing the detection limit of bioanalytical methods start during the sample preparation procedure. A robust sample preparation method is needed to evaluate the number of biomarkers. As worldwide environmental issues attract expanding consideration, all the more harmless to the ecosystem investigations are liked. Solid-phase extraction (SPE) is an appealing strategy among the sample treatment methods due to the versatility of sorbent materials, less solvent consumption, and compatibility with analytical devices. Miniaturization of the SPE gives the chance to integrate the other analytical steps in a single run, known as an easy-to-use and effective method. SPE utilizes various SPE sorbent beds such as packed beads, porous polymer monoliths, molecularly imprinted polymers, membranes, or other magnetic form microstructures to achieve high surface-to-volume ratio and appropriate chemical properties effective extraction. Also, SPE is the methodology of interest to fulfill high recovery and efficiency demands. In this review, we intend to explain more recent methods for the rational design of SPE and miniaturized SPE to determine biomarkers from biological media. The headlines are subdivided into (1) packing materials in SPE, (2) setups for sample preparation by magnetic SPE, and (3) and future perspective for the application of SPE in sample preparation for analysis of biomarkers.

Molecular imprinting technology and poly (ionic liquid)s: Promising tools with industrial application for the removal of acrylamide and furanic compounds from coffee and other foods

Coffee is one of the most consumed beverages in the world. Coffee provides to the consumer special sensorial characteristics, can help to prevent diseases, improves physical performance and increases focus. In contrast, coffee consumption supplies a significant source of substances with carcinogenic and genotoxic potential such as furan, hydroxymethylfurfural (HMF), furfural (F), and acrylamide (AA). The present review addresses the issues around the presence of such toxic substances formed in Maillard reaction (MR) during thermal treatments in food processing, from chemical and, toxicological perspectives, occurrences in coffee and other foods processed by heating. In addition, current strategies advantages and disadvantages are presented along with application of molecular imprinting technology (MIT) and poly (ionic liquid) s (PIL) as an alternative to reduce the furan, HMF, F and AA content in coffee and other foods.

Recognizing adsorption of Cd(Ⅱ) by a novel core-shell mesoporous ion-imprinted polymer: Characterization, binding mechanism and practical application

A novel monodispersed Cd(II) ion-imprinted polymer (IIP) was synthesized inside core-shell mesoporous silica (C-SMS) particles to improve the diffusion kinetics of the polymer. The synthesized IIP@C-SMS was characterized and subsequently used in solid-phase extraction (SPE) for the selective adsorption of Cd(II) in aquatic samples. The results indicated that IIP had been successfully assembled inside the C-SMS particles with a high specific surface area (546.3 m² g^-1) and uniform mesoporous size (2.07 nm). The obtained IIP@C-SMS takes only 15 min to reach the adsorption equilibrium due to the highly developed mesoporous structure. IIP@C-SMS also presented a maximal adsorption capacity (201.9 μmol g^-1) for Cd(II), which was much higher than that of NIP@C-SMS (80.3 μmol g^-1). The relative selectivity coefficient of IIP@C-SMS for Cd(II)/M(II) (M = Cu(II), Pb(II), Cr(II), and Ni(II)) were 7.15, 8.70, 7.18, and 7.36, respectively, further confirming the satisfactory selectivity of IIP@C-SMS. The adsorption isotherms of IIP@C-SMS toward Cd(II) could be described by Langmuir model; whereas the adsorption kinetics could be fitted by the pseudo-second-order model, indicating chemisorption was the rate-limiting step. The FT-IR, ITC and XPS analysis further confirmed that the Cd(II)-induced cavities during the ion-imprinting process and the coordination between Cd(II) and -SH groups were the main adsorption mechanism. Furthermore, in real samples, IIP@C-SMS-SPE adsorbed approximately 93-104% of Cd(II). This work provides new insights for the design of novel macroporous sorbents for Cd(II).

Preparation of magnetic metal organic framework and development of solid phase extraction method for simultaneous determination of fluconazole and voriconazole in rat plasma samples by HPLC

Fluconazole and voriconazole are the two broad-spectrum triazole antifungals. The present work described the fabrication method for the synthesis of the amino-modified magnetic metal-organic framework. This material was applied as a pre-sample treatment sorbent for the selective extraction of fluconazole and voriconazole in rat plasma samples. The material was fabricated by the chemical bonding approach method and was characterized by different parameters. The factors which affect the extraction efficiency of the sorbent material were also optimized in this study. Due to the optimization of solid-phase extraction conditions, the nonspecific interaction was reduced and the extraction recoveries of target drugs were increased in plasma samples. The extraction method was combined with the HPLC-UV method for the analysis. Excellent linearity (0.1-25 µg/mL), detections (0.02, 0.03 µg/mL) and quantification limits (0.04, 0.05 µg/mL) were resulted for fluconazole and voriconazole respectively. The maximum recoveries from spiked plasma samples of fluconazole and voriconazole were 86.8% and 78.6% and relative standard deviation were 0.9-2.8% and 2.2-3.6% respectively. Moreover, this sorbent material was used multiple times which was an improvement over single-use commercial sorbent materials. This validated method has practical potential for the simultaneous determination of these drugs in therapeutic drug monitoring studies as well as for routine pharmacokinetic evaluations.

Facile one-step targeted immobilization of an enzyme based on silane emulsion self-assembled molecularly imprinted polymers for visual sensors

Immobilized enzymes play significant roles in many practical applications. However, the enzymes need to be purified before immobilization by conventional immobilizing methods, and the purification process is expensive, laborious, complicated and results in a decrease of the enzymatic activity. So, we present a novel method by a facile one-step targeted immobilization of an enzyme without a purification process from complex samples. For this purpose, a novel molecularly imprinted polymer was prepared via a silane emulsion self-assembly method using boric acid-modified Fe3O4 nanoparticles as magnetic nuclei, horseradish peroxidase as a template, 3-aminopropyltriethoxysilane as a functional monomer and tetraethyl orthosilicate as a crosslinking agent. The molecularly imprinted polymers were characterized using a scanning electron microscope, X-ray photoelectron spectroscope, vibrating sample magnetometer and X-ray diffractometer. The as-prepared and characterized materials were employed to immobilize horseradish peroxidase from a crude extract of horseradish. Moreover, the immobilized horseradish peroxidase was employed to develop visual sensors for the detection of glucose and sarcosine. This study demonstrated that the molecularly imprinted polymers prepared via the silane emulsion self-assembly method can facilely immobilize horseradish peroxidase from a crude extract of horseradish without any purification process. The developed visual method based on the immobilized horseradish peroxidase shows great potential applications for the visual detection of glucose and sarcosine.

Preparation of dendritic polymer-based magnetic carrier for application of bromelain separation and purification

Bromelain has wide applications in different industries, such as food, textile, and medicine. Traditional approaches for bromelain separation and purification from solution still have many problems, including unsatisfactory binding efficiency, time-consuming operation, and costly equipment. In the present study, a new type of dendritic polymer-based magnetic carrier (GO@Fe₃ O₄ @PEI-Cu²⁺ ) was first prepared for bromelain separation and purification in solution. The histidine existing in bromelain could bind to Cu²⁺ cations adsorbed on the surface of the magnetic carrier, and the magnetic carrier showed excellent performance for bromelain separation and purification in solution, with the adsorption capacity up to 357 mg/g. The magnetic carrier also exhibited excellent property in the aspect of recyclability. It was found that the magnetic carrier also presented desirable performance for the separation and purification of bromelain from the crude extract of pineapple peel, and the bromelain structure remained intact before and after elution process. PRACTICAL APPLICATIONS: Considering many advantages of bromelain in the applications of pharmaceutical and food industries, this study is aimed at presenting a novel magnetic carrier with high stability and fabulous performance for bromelain separation and purification in solution and achieving the practical application that the magnetic carrier can efficiently separate bromelain from the crude extract of pineapple peel.

Preparation of titanium ion functionalized polydopamine coated ferroferric oxide core-shell magnetic particles for selective extraction of nucleotides from Cordyceps and Lentinus edodes

In this study, a titanium ion (Ti4+) functionalized polydopamine coated ferroferric oxide (Fe3O4@PDA@Ti4+) core-shell magnetic particle was prepared for the selective extraction of nucleotides. Firstly, different metal ions including Ti4+, Zr4+, Fe3+, Al3+, Cu2+, Zn2+, Ni2+ and Mg2+ were respectively immobilized onto Fe3O4@PDA particles and their extraction efficiency for five nucleotides [cytidine-5'-monophosphate (CMP), uridine-5'-monophosphate (UMP), guanosine-5'-monophosphate (GMP), thymidine-5'-monophosphate (TMP) and adenosine-5'-monophosphate (AMP)] were compared. Among these prepared materials, Fe3O4@PDA@Ti4+, which exhibited the highest extraction efficiency for nucleotides, was further characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. After being optimized of the extraction parameters including adsorbent amounts, extraction time, extraction temperature, type and concentration of the eluent, the prepared Fe3O4@PDA@Ti4+ magnetic particles were successfully applied for the selective extraction and determination of CMP, UMP, GMP, TMP and AMP in Cordyceps and Lentinus edodes. Good linearity (varying from 0.063 to 19.000 μg/mL, R2 > 0.999) and low limit of detection (LODs) (ranging between 0.0047 and 0.0141 μg/mL) for target analytes were achieved. These results demonstrated that the synthesized material in this study had potential for selective extraction of phosphorylated small molecular compounds in complicated matrix.