Preparation, evaluation and application of diazinon imprinted polymers as the sorbent in molecularly imprinted solid-phase extraction and liquid chromatography analysis in cucumber and aqueous samples

Recent advancements in non-enzymatic electrochemical sensor development for the detection of organophosphorus pesticides in food and environment

Organophosphorus Pesticides (OPPs) are among the extensively used pesticides throughout the world to boost agricultural production. However, persistent residues of these toxic pesticides in various vegetables, fruits, and drinking water poses detrimental health effects. Consequently, the rapid monitoring of these harmful chemicals through simple and cost-effective methods has become crucial. In such an instance, electrochemical methods offer simple, rapid, sensitive, reproducible, and affordable detection pathways. To overcome the limitations associated with electrochemical enzymatic sensors, non-enzymatic sensors have emerged as promising and simpler alternatives. The non-enzymatic sensors have demonstrated superior activity, reaching detection limit up to femto (10-15) molar concentration in recent years, leveraging higher selectivity obtained through the molecularly imprinted polymers, synergistic effects between carbonaceous nanomaterials and metals, metal oxide alloys, and other alternative approaches. Herein, this review paper provides an overview of the recent advancements in the development of non-enzymatic electrochemical sensors for the detection of commonly used OPPs, such as Chlorpyrifos (CHL), Diazinon (DZN), Malathion (MTN), Methyl parathion (MP) and Fenthion (FEN). The design method of the electrodes, electrode functioning mechanism, and their analytical performance metrics, such as limit of detection, sensitivity, selectivity, and linearity range, were reviewed and compared. Furthermore, the existing challenges within this rapidly growing field were discussed along with their potential solutions which will facilitate the fabrication of advanced and sustainable non-enzymatic sensors in the future.

Design of fluorescent method for sensing toxic diazinon in water samples using PbS quantum dots-based gelatin

In this current article, a chemical sensor was synthesized PbS functionalized with gelatin quantum dots for toxic diazinon. The measure of toxic diazinon was performed using concentration 0.5 µM, PbS quantum dot-gelatin nanocomposites sensor, pH 6, and time 50 s, wavelength 300 nm, in phosphate buffer solution. Under the optimum conditions, the detection limit linear range was obtained (0.01-20.0 µg L^-1). The standard deviation of less than (1.0%), and detection limits (3S/m) of the method (0.01 µg L^-1) and quantification (LOQ) of (0.099 µg L^-1), for determination of toxic diazinon, was obtained. The observed outcomes confirmed the suitability recovery and a very low detection limit for measuring the toxic diazinon. The Chemical PbS Quantum Dot-Gelatin nanocomposites sensor as excellent sensor was applied to measure and analyze residue toxic diazinon in water samples.

Sensitive and selective magnetic dispersive microextraction of diazinon from urine samples by molecularly imprinted polymer based on core-shell metal-organic frameworks

A core-shell magnetic metal-organic framework (Fe₃O₄ SiO₂/ PAEDTC@ MIL- 101 (Fe)) was synthesized as the substrate and then covered with a surface molecularly imprinted polymer (MIP) layer. Next, Fe₃O₄ SiO₂/ PAEDTC@ MIL- 101 (Fe) @ MIP was characterized by XRD, FT-IR, BET, VSM, TEM, and FE-SEM techniques and applied for selective, fast, and sensitive magnetic dispersive solid-phase microextraction (M-DµSPE) of diazinon from urine samples by the GC- FID detection method. The key experimental variables affecting M-DµSPE were studied and optimized by central composite design (CCD). Under optimum conditions (5 mL; sample at pH: 7.0, the mass of solid sorbent; 6 mg, extraction time; 4 min, acetonitrile as an eluent solvent; 1.5 mL, and desorption time; 3 min, and then reconstituted with 100 µL of methanol), the proposed method exhibits high sensitivity with limits of detection and quantification of 0.005 and 0.017 ng mL^-1, respectively. Excellent extraction recovery (98.5 %), wide linearity range (0.02-200000 ng mL^-1, R² > 0.992), high enrichment factors (47-53), and satisfactory precision (<6.3 % RSD) were achieved. The MIP- MOF@ M-DµSPE -GC-FID method can be used with high precision and wide linearity to extract and analyze trace levels of diazinon in real urine samples.

Zr-based metal organic framework nanoparticles coated with a molecularly imprinted polymer for trace diazinon surface enhanced Raman scattering analysis

In this study, a new surface imprinted polymer of type MOFs-MIPs was synthesized with diazinon as template and Zr-based metal organic framework (UiO-67) as matrix for trace diazinon surface enhanced...

Functional Hybrid Micro/Nanoentities Promote Agro-Food Safety Inspection

The rapid development of nanomaterials has provided a good theoretical basis and technical support to solve the problems of food safety inspection. The combination of functionalized composite nanomaterials and well-known detection methods is gradually applied to detect hazardous substances, such as chemical residues and toxins, in agricultural food products. This review concentrates on the latest agro-food safety inspection techniques and methodologies constructed with the assistance of new hybrid micro/nanoentities, such as molecular imprinting polymers integrated with quantum dots (MIPs@QDs), molecular imprinting polymers integrated with upconversion luminescent nanoparticles (MIPs@UCNPs), upconversion luminescent nanoparticles combined with metal-organic frameworks (UCNPs@MOFs), magnetic metal-organic frameworks (MOFs@Fe₃O₄), magnetic covalent-organic frameworks (Fe₃O₄@COFs), covalent-organic frameworks doped with quantum dots (COFs@QDs), nanobody-involved immunoassay for fast inspection, etc. The presented summary and discussion favor a relevant outlook for further integrating various disciplines, like material science, nanotechnology, and analytical methodology, for addressing new challenges that emerge in agro-food research fields.

Advances in Molecularly Imprinted Systems: Materials, Characterization Methods and Analytical Applications

Introduction:

A molecular imprinting is one of the fascinating modification methods that employ molecules as targets to create geometric cavities for recognition of targets in the polymeric matrix. This method provides a broad versatility to imprint target molecules with different size, three-dimensional structure and physicochemical features. In contrast to the complex and timeconsuming laboratory surface modification procedures, this method offers a rapid, sensitive, inexpensive, easy-to-use, and selective approach for the diagnosis, screening and monitoring disorders. Owing to their unique features such as high selectivity, physical and chemical robustness, high stability, low-cost and reusability of this method, molecularly imprinted polymers have become very attractive materials and been applied in various applications from separation to detection.

Background:

The aims of this review are structured according to the fundamentals of molecularly imprinted polymers involving essential elements, preparation procedures and also the analytical applications platforms. Finally, the future perspectives to increase the development of molecularly imprinted platforms.

Methods:

A molecular imprinting is one of the commonly used modification methods that apply target as a recognition element itself and provide a wide range of versatility to replica other targets with a different structure, size, and physicochemical features. A rapid, easy, cheap and specific recognition approach has become one of the investigation areas on, especially biochemistry, biomedicine and biotechnology. In recent years, several technologies of molecular imprinting method have gained prompt development according to continuous use and improvement of traditional polymerization techniques.

Results:

The molecularly imprinted polymers with excellent performances have been prepared and also more exciting and universal applications have been recognized. In contrast to the conventional methods, the imprinted systems have superior advantages including high stability, relative ease and low cost of preparation, resistance to elevated temperature, and pressure and potential application to various target molecules. In view of these considerations, molecularly imprinted systems have found application in various fields of analytical chemistry including separation, purification, detection and spectrophotometric systems.

Conclusion:

Recent analytical methods are reported to develop the binding kinetics of imprinted systems by using the development of other technologies. The combined platforms are among the most encouraging systems to detect and recognize several molecules. The diversity of molecular imprinting methods was overviewed for different analytical application platforms. There is still a requirement of more knowledge on the molecular features of these polymers. A next step would further be the optimization of different systems with more homogeneous and easily reachable recognition sites to reduce the laborious in the accessibility in the three-dimensional polymeric materials in sufficient recognition features and also better selectivity and sensitivity for a wide range of molecules.

Fluorometric determination of acetamiprid using molecularly imprinted upconversion nanoparticles

This paper describes the fabrication of an imprinted fluorescent nanoprobe based on SiO₂-coated NaYF₄: Yb, Er upconversion nanoparticles (UCNP) encapsulated with a molecularly imprinted polymer (MIP) for determination of acetamiprid. The fluorescent MIP nanoprobe was prepared using UCNP as the material for fluorescence signal readout, acetamiprid as template molecule, methylacrylic acid (MAA) as functional monomer, and ethyleneglycol dimethacrylate (EGDMA) as cross-linking agent. The molecular imprinting layers were immobilized on the surface of the UCNP@SiO₂ by polymerization which occurred between the double bonds. UCNP@MIP shows a high selectivity towards acetamiprid with an imprinting factor (IF) of 7.84. When UCNP@MIP combines with acetamiprid, the fluorescence of the UCNP@MIP can be quenched due to the photo-induced electron transfer. Under optimum conditions, the fluorescence method shows a good linear relationship between the decreased fluorescence intensity (with excitation/emission peaks at 980/542 nm) and the variation of acetamiprid in the concentration range 20 to 800 ng mL^-1. The limit of detection (LOD) is 8.3 ng mL^-1. This fluorescence method was also successfully applied to detect acetamiprid in apple and strawberry samples. The recoveries range from 89.6 to 97.9%, with relative standard deviations between 1.6 and 2.9% (n = 5). Graphical abstractA simple fluorescence nanoprobe which integrates upconversion nanoparticles (UCNPs) and molecular imprinting polymer (MIP) was developed for the determination of acetamiprid. The limit of the detection was determined as 8.3 ng mL^-1. The selectivity was enhanced by molecular imprinting, and the sensitivity was improved by the high sensitivity of the fluorescence emitted from the UCNPs.

Influence of pH, ionic strength and natural organic matter concentration on a MIP-Fluorescent sensor for the quantification of DNT in water

The effect of sample water chemistry on a carbon dot labeled molecularly imprinted polymer (AC-MIP) sensor for the detection of 2,4-dinitrotoluene (DNT) was investigated. Hydrogel MIP films were fabricated and tested in DNT solutions in various matrices, representative of natural water conditions, to assess applicability of the sensors to real water samples. The effect of pH, natural organic matter (NOM), ionic strength and cation type on the swelling of the hydrogel and fluorescence quenching was investigated. An increase in ionic strength from 1 mM to 100 mM produced a quenching amount of MIPs decreased of about 19% and 30% with NaCl and CaCl₂ respectively. In the range of pH tested, from 4 to 9, quenching was higher at basic environment for both MIPs and non-imprinted polymers (NIPs) due to increased hydrogel swelling. NOM contributed to the background quenching, but the effect could be addressed by an adjusted calibration equation. In both lake and tap water, DNT concentrations read by the sensors were close to the values measured by HPLC, within 72%–105% of true values. The AC-MIP films fabricated in this work are promising materials for the detection of water contamination in the field and the quantitative analysis of DNT concentration.

Preparation and application of magnetic molecular imprinted polymers for extraction of cephalexin from pork and milk samples

A highly selective and effective method was successfully developed using magnetic molecular imprinted polymers (MMIPs) as solid-phase extraction (SPE) coupled with high performance liquid chromatography-ultraviolet detector (HPLC-UV) to rapidly determine cephalexin (CFX) in complex animal-derived food. MMIPs were creatively synthesized via suspension polymerization using Fe₃O₄ magnetic nanoparticles as supporter, CFX as template, acrylamide (AM) as functional monomer, and ethylene glycol dimethacrylate (EGDMA) as cross-linker. The MMIPs were characterized using X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). The binding process fitted well with pseudo-second-order model with good selectivity. Scatchard plot analysis suggested that MMIPs have two types of binding sites with the Q_max of 24.18 mg g^-1 and 40.25 mg g^-1, respectively. And Langmuir model proved that the recognition sites were uniformly distributed in a monolayer on the surface of MMIPs. The methodological assessment showed good applicability of MMIPs with excellent recovery (85.5%-94.0%), precision (1.2%-2.4%), and stability (intra-day 1.3%-3.6%; inter-day 2.6%-4.3%) in determining CFX content. In addition, the linearity of the calibration curve was good in the range of 0.02-5.00 mg L^-1, with a sensitive detection limit of 5.00 μg kg^-1. The results above suggest that the obtained MMIPs exert good performance for separation of CFX in animal-derived food, and the proposed method is suitable for the reliable determination of CFX in complex samples.

Antagonistic effects of Spirulina platensis on diazinon-induced hemato-biochemical alterations and oxidative stress in rats

Spirulina platensis (SP) is a traditionally used microalga for a wide range of pharmacological activities, including amelioration of heavy metals and pesticides toxicity. This study evaluated the antioxidant and organoprotective effects of SP against diazinon (DZN)-induced subacute toxicity on the blood, heart, liver, and kidneys of male Wistar albino rats. Diazinon (20 mg/kg, subcutaneous) was administered to animals either alone or along with an oral pure SP powder at doses of 500 and 1000 mg/kg. Alterations in hematological and serum biochemical parameters, as well as oxidative stress markers in the hepatic, renal, and cardiac tissues were evaluated, using colorimetric spectrophotometric techniques. The obtained results revealed that in comparison to the control group, DZN-treated rats exhibited significantly lower (p < 0.05) red blood cells and platelets counts, hemoglobin and hematocrit values, and activities of serum acetylcholinesterase and tissue antioxidant enzymes (glutathione peroxidase, superoxide dismutase, and catalase). Meanwhile, biochemical analysis showed significantly higher (p < 0.05) white blood cells count, serum concentrations of tumor necrosis factor-α and cardiac [creatine kinase (CK) and CK-muscle/brain fraction], hepatic [transaminases and alkaline phosphatase], and renal [uric acid, urea and creatinine] injury markers, and tissue levels of malondialdehyde (a marker of lipid peroxidation) in the DZN-intoxicated group, compared to normal controls. Interestingly, the administration of SP significantly ameliorated the previous hemato-biochemical alterations and mitigated DZN-induced organ injuries and oxidative stress. In conclusion, the natural antioxidant microalga (SP) effectively alleviated the DZN-induced hematologic alterations and organ injuries, probably through its antioxidant and anti-inflammatory activities.

The conjunction of a new ultrasonic-assisted dispersive solid-phase extraction method with HPLC-DAD for the trace determination of diazinon in biological and water media

Herein, a new ultrasonic-assisted dispersive solid-phase extraction method was successfully developed for the trace detection of diazinon.

Molecularly imprinted polymer nanoparticles-based electrochemical sensor for determination of diazinon pesticide in well water and apple fruit samples

In this research, an electrochemical sensor based on molecularly imprinted polymer (MIP) nanoparticles for selective and sensitive determination of diazinon (DZN) pesticides was developed. The nanoparticles of diazinon imprinted polymer were synthesized by suspension polymerization and then used for modification of carbon paste electrode (CPE) composition in order to prepare the sensor. Cyclic voltammetry (CV) and square wave voltammetry (SWV) methods were applied for electrochemical measurements. The obtained results showed that the carbon paste electrode modified by MIP nanoparticles (nano-MIP-CP) has much higher adsorption ability for diazinon than the CPE based non-imprinted polymer nanoparticles (nano-NIP-CP). Under optimized extraction and analysis conditions, the proposed sensor exhibited excellent sensitivity (95.08 μA L μmol(-1)) for diazinon with two linear ranges of 2.5 × 10(-9) to 1.0 × 10(-7) mol L(-1) (R (2) = 0.9971) and 1.0 × 10(-7) to 2.0 × 10(-6) mol L(-1) (R (2) = 0.9832) and also a detection limit of 7.9 × 10(-10) mol.L(-1). The sensor was successfully applied for determination of diaznon in well water and apple fruit samples with recovery values in the range of 92.53-100.86 %. Graphical abstract Procedure for preparation of electrochemical sensor based on MIP nanoparticles for determination of diazinon.

Detection of Organophosphorus Pesticides with Colorimetry and Computer Image Analysis

Organophosphorus pesticides (OPs) represent a very important class of pesticides that are widely used in agriculture because of their relatively high-performance and moderate environmental persistence, hence the sensitive and specific detection of OPs is highly significant. Based on the inhibitory effect of acetylcholinesterase (AChE) induced by inhibitors, including OPs and carbamates, a colorimetric analysis was used for detection of OPs with computer image analysis of color density in CMYK (cyan, magenta, yellow and black) color space and non-linear modeling. The results showed that there was a gradually weakened trend of yellow intensity with the increase of the concentration of dichlorvos. The quantitative analysis of dichlorvos was achieved by Artificial Neural Network (ANN) modeling, and the results showed that the established model had a good predictive ability between training sets and predictive sets. Real cabbage samples containing dichlorvos were detected by colorimetry and gas chromatography (GC), respectively. The results showed that there was no significant difference between colorimetry and GC (P > 0.05). The experiments of accuracy, precision and repeatability revealed good performance for detection of OPs. AChE can also be inhibited by carbamates, and therefore this method has potential applications in real samples for OPs and carbamates because of high selectivity and sensitivity.

Selective extraction and concentration of mebendazole in seawater samples using molecularly imprinted polymer as sorbent

A high selective pre-treatment method for the extraction and analysis of mebendazole in environmental water samples was developed based on molecularly imprinted solid-phase extraction (MISPE). The mebendazole imprinted polymers were synthesized in acetonitrile using methacrylic acid and ethylene glycol dimethacrylate as functional monomer and cross-linker respectively. The imprinted materials showed high adsorption ability for mebendazole and were applied as special solid-phase extraction sorbents for selective separation of mebendazole. An off-line MISPE procedure was developed for the purification and enrichment of mebendazole from natural seawater samples prior to high-performance liquid chromatography analysis. The recoveries of spiked seawater on the MISPE cartridges were from 83.0% to 90.6%, and the values of the relative standard deviation were in the range of 2.78-4.13% (n=3). The satisfied results showed that this pre-treatment methodology for extracting mebendazole in seawater was simple and effective.