Methyl parathion imprinted polymer nanoshell coated on the magnetic nanocore for selective recognition and fast adsorption and separation in soils

Biomass waste-derived magnetic material coated with dual-dummy-template molecularly imprinted polymer for simultaneous extraction of organophosphorus and carbamate pesticides

An eco-friendly biomass waste-derived magnetic material coated with a dual-dummy-template molecularly imprinted polymer was fabricated using aqueous ethanol as a green porogen, lower amounts of toxic compounds as template molecules, and tyrosine and tryptophan as biocompatible binary monomers. The binding characteristics and selectivity of the material toward pesticides were assessed. High adsorption capacities ranging from 150.11 to 509.09 mg g-1 and imprinting factors reaching 2.2 were achieved within just 30 s. The material was applied for extraction of organophosphorus and carbamate pesticides prior to HPLC analysis. Under the optimum conditions, low limits of detection and quantitation were achieved, with ranges of 0.05-1.49 μg/L and 0.18-5.00 μg/L, respectively. The established approach enables efficient analysis of vegetable and fruit samples, yielding satisfactory recoveries ranging between 80 and 110 %. The method showed promise as an analytical method for the sensitive enrichment of pesticide residues in vegetable and fruit samples.

Molecularly imprinted polymer-coated paper for the selective extraction of organophosphorus pesticides from fruits, vegetables, and cereal grains

Biodegradable molecularly imprinted polymer-coated paper (MIP@paper) was effectively produced by polymerization using azinphos-methyl as a template molecule, terephthalic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, and aqueous ethanol as a green porogenic solvent. The material was subsequently composited onto cellulose paper, which served as the natural substrate, by dip coating with the aid of chitosan and citric acid natural adhesive. The properties, such as static and dynamic adsorption, selectivity, and reusability, were assessed. At rapid adsorption equilibrium (10 min), the MIP@paper had a high adsorption capacity in the range of 2.5-3.7 mg g-1 and good recognition with imprinting factors up to 2.1. In addition, the proposed MIP@paper was utilized efficiently as a sorbent for dispersive solid phase extraction (d-SPE) of eight organophosphorus pesticides (OPPs) prior to high-performance liquid chromatography (HPLC) analysis. The d-SPE-HPLC method displayed low detection limits of 1.2-4.5 μg kg-1 and significant enrichment factors (up to 320-fold). The proposed method was effectively applied for the determination of OPP residues in agricultural products, including fruits, vegetables, and cereal grains, with satisfactory spiked recoveries (80.1-119.1 %). Thus, the MIP@paper material provided a selective and environmentally favorable method for extracting and determining organophosphorus pesticides.

Programmable dual-electric-field immunosensor using MXene-Au-based competitive signal probe for natural parathion-methyl detection

Immunosensor is a promising tool for natural parathion-methyl (PTM) detection, and its analytical advantages can be magnified by introducing flexibly-fabricating technique. Herein, we present a dual-electric-field PTM immunosensor on highly-compatible screen-printed electrode (SPE). MXene-Au, the product of in-situ gold nanoparticle growth on MXene, provides considerable binding sites for PTM antigen (ATG) and methylene blue (MB). During sensing, the MXene-Au-MB-ATG probe competitively binds antibody against PTM, composing a ratiometric immune-system. With DC-biased sine excitations from complementary waveforms, on-chip electric field couple improves immunoreactions among PTM, probe, and antibody. Electric field distribution is programmed by trimming bypass resistors to pursue optimal performance. Probe synthesis is solidly proven with morphological examinations, and competition mechanism between the probe and target PTM is clarified in electrochemical analyses. Remarkably, this method brings less consumption of immune time than electric-field-free or solo-electric-field setup (50 s vs. 900 or 70 s), and simultaneously provides more powerful ratiometric signal than the rivals. Log-linear relationship, between PTM level and sensor readout, is established in 0.02-38 ng/mL, and limit of detection is found as 0.01 ng/mL. This method is applied in laboratorial and natural PTM analyses, and the readouts are consistent with high performance liquid chromatography and recovery test.

Dual-Functional Monomer MIPs and Their Comparison to Mono-Functional Monomer MIPs for SPE and as Sensors

A molecularly imprinted polymer (MIP) is a synthetic polymer that has characteristics such as natural receptors which are able to interact and bind to a specific molecule that is used as a template in the MIP polymerization process. MIPs have been widely developed because of the need for more selective, effective, and efficient methods for sample preparation, identification, isolation, and separation. The MIP compositions consist of a template, monomer, crosslinker, initiator, and porogenic solvent. Generally, MIPs are only synthesized using one type of monomer (mono-functional monomer); however, along with the development of MIPs, MIPs began to be synthesized using two types of monomers to improve the performance of MIPs. MIPs used for identification, separation, and molecular analysis have the most applications in solid-phase extraction (SPE) and as biochemical sensors. Until now, no review article has discussed the various studies carried out in recent years in relation to the synthesis of dual-functional monomer MIPs. This review is necessary, as an improvement in the performance of MIPs still needs to be explored, and a dual-functional monomer strategy is one way of overcoming the current performance limitations. In this review article, we discuss the techniques commonly used in the synthesis of dual-functional monomer MIPs, and the use of dual-functional monomer MIPs as sorbents in the MI-SPE method and as detection elements in biochemical sensors. The application of dual-functional monomer MIPs showed better selectivity and adsorption capacity in these areas when compared to mono-functional monomer MIPs. However, the combination of functional monomers must be selected properly, in order to achieve an effective synergistic effect and produce the ideal MIP characteristics. Therefore, studies regarding the synergistic effect of the MIP combination still need to be carried out to obtain MIPs with superior characteristics.

Nanostructured Materials for Water Purification: Adsorption of Heavy Metal Ions and Organic Dyes

Chemical water pollution poses a threat to human beings and ecological systems. The purification of water to remove toxic organic and inorganic pollutants is essential for a safe society and a clean environment. Adsorption-based water treatment is considered one of the most effective and economic technologies designed to remove toxic substances. In this article, we review the recent progress in the field of nanostructured materials used for water purification, particularly those used for the adsorption of heavy metal ions and organic dyes. This review includes a range of nanostructured materials such as metal-based nanoparticles, polymer-based nanomaterials, carbon nanomaterials, bio-mass materials, and other types of nanostructured materials. Finally, the current challenges in the fields of adsorption of toxic materials using nanostructured materials are briefly discussed.

Application, advancement and green aspects of magnetic molecularly imprinted polymers in pesticide residue detection

Molecularly imprinted polymers (MIPs) have added a vital contribution to food quality and safety with the effective extraction of pesticide residues due to their unique properties. Magnetic molecularly imprinted polymers (MMIPs) are a superior approach to overcome stereotypical limitations due to their unique core-shell and novel composite structure, including high chemothermal stability, rapid extraction, and high selectivity. Over the past two decades, different MMIPs have been developed for pesticide extraction in actual food samples with a complex matrix. Nevertheless, such developments are desirable, yet the synthesis and mode of application of MMIP have great potential as a green chemistry approach that can significantly reduce environmental pollution and minimize resource utilization. In this review, the MMIP application for single or multipesticide detection has been summarized by critiquing each method's uniqueness and efficiency in real sample analysis and providing a possible green chemistry exploration procedure for MMIP synthesis and application for escalated food and environmental safety.

Colorimetric Detection of Organophosphate Pesticides Based on Acetylcholinesterase and Cysteamine Capped Gold Nanoparticles as Nanozyme

Organophosphates (OPs) are neurotoxic agents also used as pesticides that can permanently block the active site of the acetylcholinesterase (AChE). A robust and sensitive detection system of OPs utilising the enzyme mimic potential of the cysteamine capped gold nanoparticles (C-AuNPs) was developed. The detection assay was performed by stepwise addition of AChE, parathion ethyl (PE)-a candidate OP, acetylcholine chloride (ACh), C-AuNPs, and 3, 3′, 5, 5′-tetramethylbenzidine (TMB) in the buffer solution. The whole sensing protocol completes in 30–40 min, including both incubations. The Transmission Electron Microscopy (TEM) results indicated that the NPs are spherical and have an average size of 13.24 nm. The monomers of C-AuNPs exhibited intense catalytic activity (nanozyme) for the oxidization of TMB, revealed by the production of instant blue colour and confirmed by a sharp peak at 652 nm. The proposed biosensor’s detection limit and linear ranges were 5.8 ng·mL⁻¹ and 11.6–92.8 ng·mL⁻¹, respectively, for PE. The results strongly advocate that the suggested facile colorimetric biosensor may provide an excellent platform for on-site monitoring of OPs.

Eco-friendly fabrication of a magnetic dual-template molecularly imprinted polymer for the selective enrichment of organophosphorus pesticides for fruits and vegetables

A magnetic dual-template molecularly imprinted polymer (DMIP) was successfully prepared in an aqueous medium and used as a sorbent for the selective extraction of organophosphorus pesticides prior to analysis by high-performance liquid chromatography (HPLC). The binding properties and selectivity of DMIP toward organophosphorus were evaluated and compared with those of a non-imprinted polymer. The established magnetic dispersive solid-phase extraction (MDSPE) method using DMIP exhibited fast enrichment of the target analytes within 60 s for adsorption and 30 s for desorption. Good linearities in the range of 0.5-2000 μg L^-1 with coefficients of determination (R²) greater than 0.9930 were observed. The method provides low limits of detection of 0.062-0.195 μg L^-1 and limits of quantification of 0.210-0.640 μg L^-1 with relative standard deviations of less than 9.5% for intra- and inter-day analyses. The enrichment factors ranged from 464 to 621. Satisfactory recoveries ranged from 81.3 to 110.0% with relative standard deviations below 11%.

Multivariate Assessment of Procedures for Molecularly Imprinted Polymer Synthesis for Pesticides Determination in Environmental and Agricultural Samples

In the case of quantitative and qualitative analysis of pesticides in environmental and food samples, it is required to perform a sample pre-treatment process. It allows to minimalize the impact of interferences on the final results, as well as increase the recovery rate. Nowadays, apart from routinely employed sample preparation techniques such as solid-phase extraction (SPE) or solid-phase microextraction (SPME), the application of molecularly imprinted polymers (MIPs) is gaining greater popularity. It is mainly related to their physicochemical properties, sorption capacity and selectivity, thermo-mechanical resistance, as well as a wide range of polymerization techniques allowing to obtain the desired type of sorption materials, adequate to a specific type of pesticide. This paper targets to summarize the most popular and innovative strategies since 2010, associated with the MIPs synthesis and analytical procedures for pesticides determination in environmental and food samples. Application of multi-criteria decision analysis (MCDA) allows for visualization of the most beneficial analytical procedures in case of changing the priority of each step of analysis (MIPs synthesis, sample preparation process—pesticides extraction, chromatographic analysis) bearing in mind metrological and environmental issues.

Synthesis and characterization of magnetic molecularly imprinted polymers for effective extraction and determination of kaempferol from apple samples

The specific of magnetic molecularly imprinted polymers (Fe3O4@SiO2-MIPs) for kaempferol were fabricated by using acrylamide (AM) as the functional monomer, azobisisobutyronitrile (AIBN) as the initiator and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. The Fe3O4@SiO2-MIPs showed high adsorption capacity (3.84 mg/g) for kaempferol, and the adsorption equilibrium was achieved within 50 min. The specific recognition capacity of Fe3O4@SiO2-MIPs was 3.02 times as high as that of Fe3O4@SiO2-NIPs. The Fe3O4@SiO2-MIPs showed high selectivity towards kaempferol over structural analogues. The recoveries of proposed method at three spiked levels analysis were ranged from 90.5% to 95.4% with the relative standard deviations (RSD) less than 5%. The obtained Fe3O4@SiO2-MIPs were successfully applied for the extraction and determination of kaempferol from apple samples. The established method was simple and feasible, which showed high selectivity, fast separation and satisfactory recoveries for real sample analysis.

Magnetic solid phase extraction sorbents using methyl-parathion and quinalphos dual-template imprinted polymers coupled with GC-MS for class-selective extraction of twelve organophosphorus pesticides

A novel magnetic dual-template molecularly imprinted polymer (DMIP) was prepared with methyl-parathion and quinalphos as templates. For comparison, a series of single-template polymers with only methyl-parathion (MPMIP) or quinalphos (QPMIP) as template as well as a non-imprinted polymer (NIP) in the absence of the template, were synthesized using the same procedure of DMIP. The obtained MIPs were characterized by scanning electron microscopy(SEM), Fourier transform infrared (FT-IR) spectroscopy, vibrating sample magnetometer (VSM), and X-ray diffraction (XRD). The properties including kinetic effect, thermodynamic effect, selectivity, and reusability of MIPs were investigated . Only DMIP possessed high affinity and good recognition for all twelve OPPs including quinalphos, isazophos, chlorpyrifos-methyl, chlorpyrifos, methidathion, triazophos, profenofos, fenthion, fenitrothion, methyl-parathion, parathion, and paraoxon in comparison to MPMIP, QPMIP, or NIP. Moreover, DMIP was used as magnetic solid phase extraction (MSPE) sorbent for the pre-concentration of twelve OPPs in cabbage samples. The developed DMIP-MSPE-GC-MS method showed high sensitivity, low LODs (1.62-13.9 ng/g), fast adsorption equilibrium (10 min), and acceptable spiked recoveries (81.5-113.4%) with relative standard deviations (RSD) in the range 0.05-7.0% (n = 3). The calibration plots were linear in the range 10-800 ng/mL with coefficients of determination (R²) better 0.99 for all twelve compounds. These results suggest that the DMIP is applicable for rapid determination and high throughput analysis of multi-pesticide residues. Graphical abstract.

Electrochemical sensing of methyl parathion on magnetic molecularly imprinted polymer

The electrochemical detection of methyl parathion in fish was performed by preconcentrating the pesticide on magnetic molecularly imprinted polymer and further readout on magneto-actuated electrode by square wave voltammetry. The magnetic molecularly imprinted polymer was synthesized by a magnetic core-shell strategy, using methacrylic acid as a functional monomer, and selected by theoretical calculation using the density functional theory (DFT). The characterization of this material was performed by SEM, TEM and XRD. Moreover, the binding capacity and selectivity towards methyl parathion was studied and compared with the corresponding magnetic non-imprinted polymer. The magneto-actuated electrochemical sensor showed outstanding analytical performance for the detection of methyl parathion in fish, with a limit of detection of as low as 1.22 × 10^-6 mg L^-1 and recovery values ranging from 89.4% to 94.7%. The magnetic molecularly imprinted polymer successfully preconcentrated the analyte from the complex samples and paves the way to incorporate this material in other platforms for the detection of this pesticide in the field of environmental control and food safety.

Recent Progress of Imprinted Nanomaterials in Analytical Chemistry

Molecularly imprinted polymers (MIPs) are a type of tailor-made materials that have ability to selectively recognize the target compound/s. MIPs have gained significant research interest in solid-phase extraction, catalysis, and sensor applications due to their unique properties such as low cost, robustness, and high selectivity. In addition, MIPs can be prepared as composite nanomaterials using nanoparticles, multiwalled carbon nanotubes (MWCNTs), nanorods, quantum dots (QDs), graphene, and clays. This review paper aims to demonstrate and highlight the recent progress of the applications of imprinted nanocomposite materials in analytical chemistry.

Synthesis and application of molecularly imprinted silica for the selective extraction of some polar organophosphorus pesticides from almond oil

The aim of this work was to prepare and evaluate molecularly imprinted polymers obtained by a sol-gel approach for the selective solid-phase extraction (SPE) of organophosphorus pesticides (OPs) from almond oil. The performances of molecularly imprinted silicas (MISs), prepared using different conditions of synthesis, were studied by applying different extraction procedures in order to determine the ability of the MISs to selectively extract ten target OPs. For this, the retention of OPs on MISs in pure media was compared with the retention on a non-imprinted silicas (NISs), used as control sorbent, to prove the presence of specific cavities. The most promising MIS allowed the selective extraction of the 3 most polar OPs among the 10 studied. The capacity was studied and the repeatability of the extraction recovery yield was demonstrated both in pure and real media. This MIS was able to selectively extract fenthion sulfoxide and dimethoate contained in almond oil extract after applying the optimized extraction procedure with recovery yields between 100 and 114%. The estimated limit of quantification (LOQ, S/N = 10), thanks to LC/MS analysis in MRM mode, between 1.2 and 4.6 μg/kg for those OPs in the almond fruits, was more than 10 times lower than the Maximum Residue Levels (MRLs) established by the European Commission. This MIS therefore shows a high potential for the analysis of those two polar OPs at trace levels from almond oils.

Application of magnetic Cd2+ ion-imprinted mesoporous organosilica nanocomposites for mineral wastewater treatment

This work demonstrates a simple strategy for producing highly selective adsorption magnetic ion imprinted mesoporous silica (MIIMS) nanocomposites.

Bifunctional monomer molecularly imprinted polymers based on the surface of multiwalled carbon nanotubes for solid-phase extraction of tartrazine from drinks

A novel bifunctional monomer MIP with an improved selectivity for tartrazine on the surface of MWNTs was synthesised.

Preparation and characterization of surface molecularly imprinted film coated on a magnetic nanocore for the fast and selective recognition of the new neonicotinoid insecticide paichongding (IPP)

The selective recognition of IPP-MMIPs and IPP-MNIPs for four kinds of neonicotinoid insecticides, including IPP, imidacloprid, thiamethoxam and thiacloprid.

Rational design of nanomaterials for water treatment

The ever-increasing human demand for safe and clean water is gradually pushing conventional water treatment technologies to their limits. It is now a popular perception that the solutions to the existing and future water challenges will hinge upon further developments in nanomaterial sciences. The concept of rational design emphasizes on 'design-for-purpose' and it necessitates a scientifically clear problem definition to initiate the nanomaterial design. The field of rational design of nanomaterials for water treatment has experienced a significant growth in the past decade and is poised to make its contribution in creating advanced next-generation water treatment technologies in the years to come. Within the water treatment context, this review offers a comprehensive and in-depth overview of the latest progress in rational design, synthesis and applications of nanomaterials in adsorption, chemical oxidation and reduction reactions, membrane-based separation, oil-water separation, and synergistic multifunctional all-in-one nanomaterials/nanodevices. Special attention is paid to the chemical concepts related to nanomaterial design throughout the review.

One-pot synthesis of magnetic molecularly imprinted microspheres by RAFT precipitation polymerization for the fast and selective removal of 17β-estradiol

A one-pot synthesis strategy was developed to prepare magnetic molecularly imprinted microspheres for the selective recognition and fast removal of 17-beta-estradiol.

A novel bifunctional molecularly imprinted polymer for determination of Congo red in food

A novel bifunctional molecularly imprinted polymer was synthesized with beta-cyclodextrins-maleic anhydride and [2-(methacryloyloxy) ethyl] trimethylammonium chloride as co-functional monomers, and applied to the determination of food.

A novel molecularly imprinted material based on magnetic halloysite nanotubes for rapid enrichment of 2,4-dichlorophenoxyacetic acid in water

A new type of magnetic halloysite nanotubes molecularly imprinted polymer (MHNTs@MIP) based on halloysite nanotubes (HNTs) with embedded magnetic nanoparticles was introduced in this study. MHNTs@MIP was prepared through surface imprinting technology, using 2,4-dichlorophenoxyacetic acid (2,4-D) as a template, 4-vinylpyridine as the monomer, divinylbenzene as cross-linking agents, and 2,2-azodiisobutyronitrile as initiator. MHNTs@MIP was characterized by Fourier Transform Infrared Spectrometer, transmission electron microscopy, X-ray diffraction, and vibrating sample magnetometer. MHNTs@MIP exhibited rapid and reliable analysis with supermagnetic properties, as well as repeated use and template-specific recognition. The adsorption capacity of magnetic halloysite nanotubes non-imprinted polymer (MHNTs@NIP) and MHNTs@MIP was 10.3mg/g and 35.2mg/g, respectively. In the detailed discussion on specific selectivity, MHNTs@MIP can be applied as an adsorbent for sample pretreatment extraction and obtain high recoveries of about 85-94%. After extraction, high-performance liquid chromatography was used to detect 2,4-D residue in water.

A molecularly imprinted electrochemical enzymeless sensor based on functionalized gold nanoparticle decorated carbon nanotubes for methyl-parathion detection

Schematic of MP MIP sensor and the possible mechanism.