Detection Of Carbofuran Research Articles

A broad-spectrum antibody-based lateral flow immunoassay for detection of carbofuran and 3-hydroxy-carbofuran

Simultaneous detection of carbofuran (CBF) and 3-hydroxy carbofuran (3-OH-CBF) in fruits and vegetables is important due to their high toxicity and widespread use in pest control. However, most lateral flow immunoassay (LFA) approaches only detection CBF. To overcome this limitation, two haptens, 6-((2,2-dimethyl-2,3-dihydrobenzofuran-7-yl)oxy)hexanoic acid and 6-((((2,2-dimethyl-2,3-dihydroben zofuran-7-yl)oxy)carbonyl)amino)hexanoic acid, named H1 and H2, were designed for broad-spectrum antibody detection of CBF and 3-OH-CBF. The highly specific monoclonal antibody (mAb) 3F4 based on hapten H1 only recognized CBF, while broad-spectrum mAbs 1D3, 6B7 and 6E8 based on hapten H2 recognized both compounds. The carbon bond to the hydroxyl group of 3-OH-CBF adopts a 28.55° angle relative to the same carbon bond of CBF, explaining the specificity of the H1-based mAb against CBF. After optimizing the antigen-antibody combination, a sensitive colloidal gold-LFA (CG-LFA) strip was constructed based on mAb 1D3 and H2-BSA for CBF and 3-OH-CBF detection following simple sample pretreatment. The established LFA had a limit of detection of 0.49–6.63 ng/mL, and adequate recoveries (69.3–105.7 %) for CBF and 3-OH-CBF in 26 fruit and vegetable samples.

Electrochemical Determination of Carbofuran Residues using WS2 Modified Electrodes

AbstractTo meet the increasing demands for food production, the utilization of cost‐effective pesticides like carbofuran (CB) becomes essential. CB poses a significant risk to human health due to its high toxicity. Therefore, accurate quantification of CB residue is essential for environmental safety and human health. Electrochemical sensors have proven to be an outstanding choice for the accurate detection and quantification of carbofuran residues. CB is electrochemically inactive and was first hydrolyzed in an alkaline medium to yield an anodically active phenolic derivative carbofuran phenol (CP). This report details the development of a voltammetric sensor for the accurate detection of CB residues utilizing the cyclic voltammetry technique and the electrochemical reactions of CP at WS2 nanosheet‐modified electrodes in phosphate buffer solution (PBS). The constructed sensor has displayed a linear range of carbofuran detection from 10–90 μM, with a limit of detection (LOD) of 0.38 μM and sensitivity of 0.303 μA μM−1 cm−2. Additionally, the developed sensor has been employed to monitor CB residues in real soil and water samples and it shows a recovery greater than 95 %. The developed sensor enables the cost‐effective monitoring of carbofuran in real samples.

Multifunctional nanoenzyme lateral flow immunoassay strip for rapid and ultrasensitive detection of carbofuran in vegetables

A lateral flow immunoassay strip (LFIAS) is one of the most frequently rapid test technologies for carbofuran (CAR). Nevertheless, the LFIAS has a poor quantitative capability and low sensitivity. And, it also requires often complex sample handling steps, making testing time longer. In this study, Fe3O4 nanoparticles were successively modified with MIL-100(Fe)-based metal-organic framework (MOF) and chloroplatinic acid hexahydrate to obtain a core-shell complex of Fe3O4-MOF-Pt. The complex had a peroxidase-mimicking activity catalytic function that enabled signal amplification and sensitivity enhancement. Upon coupling with carbofuran monoclonal antibody (CAR-mAb), the magnetic separation properties of the probe enabled target-specific enrichment. The LFIAS based on Fe3O4-MOF-Pt nanocomposites could detect CAR in the range of 0.25–50 ng mL−1 with a limit of detection (LOD) of 0.15 ng mL−1, enabling colorimetric and catalytic analysis. In addition, the method showed high specificity and stability for detecting CAR in various vegetables, and recovery rates of the spiked samples were 91.40%−102.40%. In conclusion, this study provided one-stop detection of “target enrichment-visual inspection”. While lowering the LOD, it reduced the detection time and improved the detection efficiency. The multifunctional Fe3O4-MOF-Pt nanocomposite provides an idea for the construction of novel multifunctional probes to improve the detection performance of conventional LFIAS.

Detection of carbofuran in fruits and vegetables by Raman spectroscopy combined with immunochromatography.

It has long been desired to develop rapid methods for the rapid identification and quantification of pesticides and their metabolites. Carbofuran, a representative pesticide of the carbamate group, is highly systemic and is used on vegetables, fruits and grains, which has led many countries to test for residues in food and the environment. In this study, gold and silver composite core-shell (Au@Ag) nanoparticles were used to label the carbofuran antibody and Raman molecule 5,5-dithiobis-2-nitrobenzoic acid (DTNB) to synthesize Raman immune probes. The signal value of DTNB was read using a Raman spectrometer, and the quantitative detection technology of carbofuran was established based on lateral flow immunochromatographic assay (ICA) combined with surface-enhanced Raman spectroscopy (SERS). SERS-ICA is a rapid, quantitative and ultrasensitive test for the determination of carbofuran in fruits and vegetables with a sensitivity of 0.1 pg mL-1. Consequently, the results demonstrate that the SERS-based lateral flow immunosensor developed in this study has the advantages of excellent assay sensitivity and remarkable multiplexing capability, and thus it will have great application potential in food safety monitoring.

Facile synthesis of limeonia acidissima shell derived carbon-vanadium pentoxide nanocomposite for sensitive detection of carbofuran

Generating carbonaceous materials from agricultural waste is a sustainable and environmentally friendly method of producing activated carbon. In the current work, carbon is extracted using a tubular furnace from the shell of the wood apple (Limonia acidissima) V2O5 (C/VO) and synthesized carbon were combined to form a nanocomposite. The formation of nanocomposite is confirmed by X-ray diffraction (XRD) investigations, X-ray photoelectron spectroscopy (XPS), and other morphological characterizations. Modification of glassy carbon electrode (GCE) was done using synthesized materials (C@GCE, VO@GCE, and C/VO@GCE). The enzyme-free detection of carbofuran (CBF) in 0.1 M phosphate buffer was carried out using fabricated electrodes. Among the various electrode systems, C/VO@GCE demonstrated enhanced electrochemical performance for CBF detection using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. V/C@GCE demonstrated its capacity to identify CBF within a 0.05–750 μM range, with a limit of detection (LOD) of 0.06 μM. Using DPV, the effect of several pesticides on CBF detection in the presence of C/V@GCE was assessed, and good anti-interfering properties were discovered. When the DPV approach was used to detect CBF in potatoes, the recovery rate ranged from 98.0 to 99.0 %. According to a stability study, C/V@GCE has an 80.8 % retention capacity and can detect CBF for up to 24 days. The promise of the constructed electrode towards sensor applications is indicated by the large linear range, low LOD, selectivity, and stability of C/V@GCE.

Construction of coumarin-appended calix[4]arene-based fluorescence sensor for the detection of carbofuran in cabbage.

This study presents a novel approach for the detection of carbofuran (CBF) insecticide by systematically exploring a calix[4]arene-derived fluorescence probe, CouC4S, functionalized with two coumarin-labelled cystamine linkages at the narrow edge of the calix[4]arene platform. The proposed method showed a fluorescence "signal - off" effect when CBF binds with CouC4S by quenching the fluorescence intensity of CouC4S. Its limit of detection was as low as 5.55 μM according to the emission study. The working concentration range for this ligand was observed to be up to 5-65 μM. This method could be applied for the on-spot detection of CBF in real samples such as cabbage by spiking CBFvia in situ experiments, which exhibited a limit of detection of 8.823 ppm. For the further confirmation of CouC4S:CBF binding, cyclic voltammetry, differential pulse voltammetry, powder X-ray diffraction, FT-IR spectroscopy, 1H NMR titration, MALDI-TOF and computational investigations were carried out.

Paper-based colorimetric sensor using Photoshop and a smartphone app for the quantitative detection of carbofuran.

We developed a smartphone-assisted microchemistry analyzer for the quantitative detection of carbofuran using a paper-based colorimetric sensor, Photoshop software, and a smartphone app. The changes in color of the carbofuran enzymatic reaction in the paper-based sensor were captured and analyzed using a smartphone-controlled analyzer with an LED light source and a smartphone camera. The high accuracy of this method was demonstrated for the determination of carbofuran with a linear response in the range 0.05-1.0 ppm and limits of detection (LOD) of 0.02 and 0.018 ppm using Photoshop and smartphone app colorimetric analysis, respectively. These two methods not only show the high sensitivity and highly quantitative relationships between the concentrations of commercial carbofuran and characteristic color values of the blue channel in smartphone images but were also applied to infusions of tea. Moreover, the smartphone app is able to GPS tag the location of the test and transmit the results to a website that displays quantitative results from carbofuran samples on a map.

A robust and sensitive enhanced immunochromatographic assay based on UiO-66-NH2 @Au for simultaneous detection of carbofuran and 3-hydroxy-carbofuran in fruits and vegetables

Robustness is essential to improve the analytical performance of immunochromatography. The traditional immunochromatographic assay (ICA) based on colloidal gold (AuNPs) has defects of low sensitivity and insufficient robustness. Herein, a novel composite nanocarrier of zirconium-based metal-organic frameworks@gold (UiO-66-NH2 @Au) was composed. The carrier has the same optical properties of AuNPs, and the metal-organic framework substrate can protect the antibody from extreme environments. The detection limit of the ICA based on UiO-66-NH2 @Au was about 0.1 μg/kg for carbofuran (CBF) and 3-hydroxy-carbofuran (3-OH-CBF) in pear, bean, cucumber, and cabbage. In comparison with the ICA based on AuNPs, the sensitivity has increased by 2–10 fold. In complex environments, UiO-66-NH2 @Au significantly enhances the robustness of ICA. The pH tolerance range increased from pH 6‐8 to pH 4‐10, and the organic solvent tolerance increased from 20% to 40%. The recovery rates (88.6–115.4%) and coefficient of variation (2.5–14.9%) all meet the requirements of residue detection. The novel composite nano-carrier provides a new idea for establishing immunoassay methods with enhanced sensitivity and robustness.

An electrochemical aptasensor for detection of carbofuran using gold nanoparticles decorated hierarchical porous carbon as an effective sensing platform

In this study, a novel electrochemical aptasensor for carbofuran (CBF) detection is prepared by gold nanoparticles decorated hierarchical porous carbon (Au@HPC). The prepared carbon materials show a three-dimensional hierarchical structure with a large specific surface area and a highly developed porous structure. Aptamers loading significantly improves when gold nanoparticles are embedded into the hierarchical porous carbon skeleton. Besides, Au@HPC modified electrode exhibits a large electroactive area and excellent electrochemical conductivity, serving as a promising platform for highly sensitive and selective electrochemical detection of CBF. The developed CBF electrochemical aptasensor shows a wide linear from 1.0 to 100000 pg/L with a detection limit of 0.5 pg/L, demonstrating an extraordinary sensitivity compared to other sensors for CBF detection. Additionally, the designed aptasensor was used to monitor the CBF in vegetable samples, with a recovery range from 98.4% to 104.8%. The results coincide with the standard test method, revealing its practicability in the food safety analysis.

Template-assisted synthesis of Co1Zn0.5–P/CoO/ZnO core-shell heterostructure for the electrochemical detection of carbofuran and diuron

Currently, numerous lethal hazardous substances such as insecticides, and pesticides exist in the water bodies, food products causing acute health effects in humans and animals. It is crucial to monitor & control the level of toxicity in the water bodies, and daily food cycle with rapid and cost-effective detection techniques. Therefore, we have chosen the electrochemical sensing technique for the individual & simultaneous determination of carbofuran (CF) and diuron (DU) in environmental water and food samples. Herein, the core–shell structured Co1Zn0.5-P/CoO/ZnO hybrid was prepared as a dynamic electrocatalyst for the sensing of CF and DU. The microstructural features of the Co1Zn0.5-P/CoO/ZnO hybrid having a large surface area offers more electrocatalytic sites for electrochemical performances. Remarkably, the fabricated Co1Zn0.5-P/CoO/ZnO/GCE has enhanced active sites arising by the heterostructure results in an excellent detection limit of 1.94 nM for CF and a 4.04 nM for DU with linear concentrations of 2–429 µM (CF) and 2–149 µM (DU) for individual detection. Besides, the achieved LODs were 2.98 and 2.52 nM for simultaneous sensing of CF and DU with the linearity of 2–185 µM. The Co1Zn0.5-P/CoO/ZnO/GCE demonstrated with good storage stability, reproducibility, and excellent selectivity for CF and DU along with the potential interfering species. The environmental and food samples were analyzed to determine the levels of CF and DU, the recovery results were found to be the suitable candidate for the real-time sensing performances.

Disposable sensor electrode modified with strontium vanadate-graphene nanocomposites for rapid analysis of hazardous insecticide carbofuran in environmental media samples

Pesticides are inevitably used in intensive agrochemical practices to meet the global food demands of a continuously increasing population; however, the widespread and heavy use of pesticides disturbs the ecological balance and poses a threat to human health. Carbofuran (CBF) is a representative carbamate insecticide that affects the environment and human health. Therefore, highly accurate on-site CBF residue monitoring is essential for environmental media samples. This study realized the sensitive and rapid electrochemical sensing of CBF using monoclinic strontium vanadate (pyrovanadate)-supported graphene nanocomposite (SV-Gr). The SV-Gr nanocomposite was synthesized using the hydrothermal method, and the physicochemical properties of the SV-Gr nanocomposite were characterized via spectroscopic analyses. The SV-Gr-modified screen-printed carbon electrode (SPCE) exhibited good analytical performance in CBF detection, with a high sensitivity of 1.05 µA µM–1 cm–2 and an acceptable linear range (0.01–17.91 µM). Moreover, SV-Gr/SPCE exhibited good selectivity for highly interfering carbamate pesticides. Furthermore, the applicability of the proposed SV-Gr/SPCE sensor was investigated in environmental media samples, which achieved greater than 96 % of recoveries for all samples; thus, it is suitable for the sensitive and rapid detection of CBF in a real environment.

An ultrasensitive carbamate pesticide detection sensor based on metal molybdate encapsulated with boron doped reduced graphene oxide nanocomposite

Many pesticides are utilized in agriculture, due to the increased demand for food on a global scale. Among all other pesticides, carbofuran (CFN) is found to be the uppermost toxicity to humans. To find the presence of CFN in the food samples, we need rapid, portable, and low-cost sensors. This paper describes the improvement of an electrochemical sensor-based catalyst for the detection of carbofuran (CFN) employing a glassy carbon electrode (GCE) modified with cerium molybdate wrapped boron doped reduced graphene oxide (CMO/B- rGO/GCE). An innovative composite CMO/B-rGO was prepared by a co-precipitation process and its formation was confirmed by various techniques. CMO/B-rGO/GCE shows higher selectivity and sensitivity of 4.06 µA µM−1cm−2 towards the detection of CFN. Furthermore, under optimized practical conditions, the CMO/B-rGO sensor exhibits a low detection limit (LOD) of 0.002 µM, and the linear ranges were 0.01–365 µM respectively. Additionally, we examined the practical applicability of the CFN in food samples.

Fe3O4 Nanoparticle/Graphene Oxide Composites as Selective Probes and Self-Matrixes for Pesticide Detection by Electrochemistry and Laser Desorption/Ionization Mass Spectrometry

An Fe3O4 nanoparticle/graphene oxide (GO) magnetic nanocomposite is synthesized and first applied as a selective probe for simultaneous detection of carbofuran (CBF) and carbendazim (CBZ) by electrochemistry and LDI-MS with MS imaging in real fruit samples. The high binding energies of the Fe3O4 nanoparticle/GO magnetic nanocomposite with target pesticides are verified by density functional theory. The Fe3O4/GO nanocomposite-modified electrode enhances the electrocatalytic property of the pesticides and provides a linear range of 1–250 μM with LODs of 0.06 and 0.18 μM for CBF and CBZ, respectively. For LDI-MS, after magnetic separation, CBF and CBZ bound to the magnetic nanocomposite are readily ionized by using Fe3O4/GO as a self-matrix, leading to high ion abundance with a linear range of 0.25–1000 μM and LODs of 0.25 μM for both pesticides. Furthermore, CBF and CBZ bound to Fe3O4/GO spiked in pear are visualized by imaging MS, illustrating the distribution of these pesticides in real pear peels. LOD values obtained from both detection techniques are lower than the maximum residue level (MRL) in the database of these pesticide residues, suggesting that this platform might be an alternative tool for the selective detection of pesticide residues in fruit samples.

A paper chromatographic-based electrochemical analytical device for the separation and simultaneous detection of carbofuran and carbaryl pesticides

We developed an electrochemical paper-based device (ePAD) for the online separation and simultaneous determination of structurally similar carbofuran (CBF) and carbaryl (CBR). Our device combined paper chromatography and an electrochemical sensor as a single system for increasing the selectivity to simultaneous detection of the two pesticides. During the simultaneous detection of CBF and CBR, the separation of the two carbamate compounds depends on the differences between the movements of the substances on the chromatographic paper in the moving phase flow. The isolated pesticides were electrochemically measured using an amperometric method. Under optimal conditions, which include the effect of the mobile phase, separation channel, and the applied potential, the proposed device provides a linear range for the simultaneous determination of CBF and CBR from 0.1 to 2.0 and 0.5–7.5 mg L−1, with the limits of detection at 0.06 and 0.40 mg L−1, respectively. Furthermore, we successfully used the developed device to determine CBF and CBR in water, cucumber, and cabbage samples. The obtained results correspond to results obtained from a standard method. This developed ePAD is low-cost and uses a low sample volume (2 µL). Moreover, it is disposable, portable, and a promising tool for the on-site quantification of pesticides in actual samples.

A fatal case of Carbofuran and Para-phenylenediamine poisoning: A death mystery resolved

This case study will be beneficial for the forensic toxicology community for simultaneous detection of carbofuran, a pesticide and para-phenylenediamine (a hair dye locally known as black stone) along with their metabolites in analytically challenging samples like liver tissue and stomach contents. A 35 years old married woman was killed by her family. As per police investigation, she had extramarital affair, which was against religious and social norms. Later on, she got divorced and tied a knot with a new husband. After two months, the female was found dead when she was at her parent's home. Her husband claimed that her father and brother poisoned his wife because they never accepted their marriage. The sudden death of a healthy female was full of doubt. Therefore, the police started an investigation. Postmortem of the deceased was performed immediately. Postmortem examination revealed that her right index fingernail was broken; the lips area was blackish in colour as well as suspected stains were found on her clothes. Biological samples like liver tissue and stomach contents along with her clothes were submitted to the author's laboratory to rule out the use of any poison or drug. The colourimetric screening was performed for locally available poisons like phosphine, cyanide and black stone. The modified QuEChERS technique was adopted for the extraction of an unknown drug or poison in challenging samples like liver tissue and stomach material. Extracts were analyzed on GC-MS. Para-phenylenediamine (>5000 ng/g) and carbofuran (>1000 ng/g) were detected in stomach contents and liver. Metabolites/breakdown products of para-phenylenediamine (monoacetylayed para-phenylenediamine) and carbofuran (carbofuran phenol) were also detected. Suspected stains on the victim's clothes were found to contain carbofuran. Carbofuran and black stone, both are deadly poisons and are easily available in local markets of Pakistan. In absence of any other pathological findings, detection of these poisons would be sufficient to establish the cause of death. According to the author's knowledge, this is the first case study in which carbofuran (pesticide) and para-phenylenediamine (a tasteless poison) along with their metabolites were detected and reported in postmortem samples. Forensic toxicology analysis played a key role in solving the mystery of a woman's death.

Production and Selection of Antibody-Antigen Pairs for the Development of Immunoenzyme Assay and Lateral Flow Immunoassay Methods for Carbofuran and Its Analogues.

To produce a sensitive monoclonal antibody (mAb) for the simultaneous detection of carbofuran, benfuracarb, carbosulfan and 3-hydroxy-carbofuran, 2,3-dihydro-2,2-dimethyl-7-benzofuranmethanamine (DDB) was conjugated to bovine serum albumin (BSA) to prepare the immunogen DDB-BSA and mice were immunized. Coating antigens were prepared by conjugating DDB and 5-methoxy-2,3-dihydrobenzofuran-3-acetic acid (MDA) to BSA and ovalbumin (OVA), respectively. Furthermore, the effect of different antibody–antigen pairs on the sensitivity of ELISA and LFIA methods for the detection of carbofuran was investigated. After the immunization, a high-affinity mAb 13C8 was obtained. The ability of the coating antigen to compete with carbofuran for binding antibodies was found to be significantly different between ELISA and LFIA methods. With the antibody–antigen pair 13C8-MDA-OVA, the IC50 values of the ELISA and QD-LFIA methods for carbofuran were 0.18 ng/mL and 0.67 ng/mL, respectively. The cross-reactivity (CR) values of the two methods for benfuracarb, carbosulfan and 3-hydroxy-carbofuran ranged from 72.0% to 83.7%, while, for other carbamate pesticides, the CR values were less than 1%. The spiked recoveries of carbofuran in vegetables by the QD-LFIA method were 83–111%, with a coefficient of variation below 10%, and the test results of the actual samples were consistent with the HPLC-MS method. Overall, this study provides key materials for the development of immunoassays for carbofuran and its analogues, and the antibody–antigen pair selection strategy established in this study provides useful insights for the development of sensitive immunoassays for other compounds.

Bio-derived solvent-based dispersive liquid-liquid microextraction followed by smartphone digital image colorimetry for the detection of carbofuran in cereals

Bio-derived solvent-based dispersive liquid-liquid microextraction coupled with smartphone digital image colorimetry (BDS-DLLME with SDIC) was established to detect carbofuran in cereals. Carbofuran was hydrolyzed to benzofuranol by adding Na2CO3 solution. Bio-derived solvent p-cymene as the extractant and acetic acid as the dispersant were utilized in the DLLME process. The Na2CO3 and acetic acid reacted to generate CO2 bubbles, increasing the contact area between the extractant and sample solution. Thus, the rapid and efficient extraction of benzofuranol was achieved. Fe3O4 nanoparticles catalyzed the oxidative coupling reaction between benzofuranol and 4-aminoantipyrine in the presence of H2O2. Thus, the colorless solution was changed to purple-red which was captured using a smartphone and analyzed with an RGB system, achieving the quantitative detection of carbofuran. The concentration of carbofuran had a good linear relationship in the range of 0.02–20 mg kg−1. The limit of quantification was 0.018 mg kg−1, and the limit of detection was 0.005 mg kg−1. This method was successfully applied to analyze cereal samples with the recoveries of 91.1–113.8%. The BDS-DLLME with SDIC method was used to detect carbofuran with good sensitivity, selectivity, and reliability. The developed method has broad application prospects in rapid and efficient extraction and detection.

An Effective Surface Design Based on a Graphene Oxide Decorated by Silver Nanoparticles for Detection of Carbofuran in Vegetable Samples

An Effective Surface Design Based on a Graphene Oxide Decorated by Silver Nanoparticles for Detection of Carbofuran in Vegetable Samples

Novel Dual-Color Immunochromatographic Assay Based on Chrysanthemum-like Au@polydopamine and Colloidal Gold for Simultaneous Sensitive Detection of Paclobutrazol and Carbofuran in Fruits and Vegetables.

To ensure food safety and prevent the toxic effects of paclobutrazol (PBZ) and carbofuran (CAR) on humans, a sensitive and rapid method for the detection of PBZ and CAR in fruits and vegetables is required. Herein, a highly sensitive PBZ monoclonal antibody (PBZ mAb) and CAR monoclonal antibody (CAR mAb) with half-inhibitory concentrations (IC50) at 0.77 and 0.82 ng mL−1 were prepared, respectively. We proposed a novel dual-color immunochromatographic assay (ICA) with two test lines (T1 and T2) and an independent control line (C) based on chrysanthemum-like Au@Polydopamine (AuNC@PDA) and colloidal gold (AuNPs) for the simultaneous and sensitive detection of PBZ and CAR with naked-eye detection limits of 10 and 5 μg kg−1, respectively. The limits of detection (LOD) for PBZ and CAR were 0.117 and 0.087 μg kg−1 in orange, 0.109 and 0.056 μg kg−1 in grape, and 0.131 and 0.094 μg kg−1 in cabbage mustard, respectively. The average recoveries of PBZ and CAR in orange, grape, and cabbage mustard were 97.86−102.83%, with coefficients of variation from 8.94 to 11.05. The detection results of this method for 30 samples (orange, grapes, and cabbage mustard) agreed well with those of liquid chromatography–tandem mass spectrometry. The novel dual-color ICA was sensitive, rapid, and accurate for the simultaneous detection of PBZ and CAR in real samples.

Efficient Preparation of a Nonenzymatic Nanoassembly Based on Cobalt-Substituted Polyoxometalate and Polyethylene Imine-Capped Silver Nanoparticles for the Electrochemical Sensing of Carbofuran.

The ever-growing exploitation of pesticides and their lethal effects on living beings have made it a dire need of the day to develop an accurate and reliable approach for their monitoring at trace levels. The designing of an enzyme-free electrocatalyst to electrochemically detect the pesticide residues is currently gaining much importance. In this study, a novel redox-sensing film was constructed successfully based on cobalt-substituted Dawson-type polyoxometalate [P2W17O61 (Co2+·OH2)]7– (Co-POM) and polyethylene imine (PEI)-capped silver nanoparticles (AgNPs). A nanohybrid assembly was fabricated on a glassy carbon electrode’s surface by alternately depositing Co-POM and PEI-AgNPs using the layer-by-layer self-assembly method. The surface morphology of the immobilized CoPOM/AgNP multilayer nanoassembly was analyzed through scanning electron microscopy along with energy-dispersive spectroscopy for elemental analysis. The redox properties and surface morphologies of fabricated assemblies were evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. The practicability and feasibility of the proposed sensing layer was tested for the detection of a highly toxic insecticide, that is, carbofuran. The fabricated sensor exhibited a limit of detection of 0.1 mM with a sensitivity of 13.11 μA mM–1 for carbofuran. The results depicted that the fabricated nonenzymatic hybrid film showed excellent electrocatalytic efficiency for the carbofuran oxidation. Furthermore, the obtained value of “apparent Km”, that is, 0.4 mM, illustrates a good electro-oxidation activity of the sensor for the detection of carbofuran. The exceptionally stable redox activity of Co-POM, high surface area and greater conductivity of AgNPs, and the synergistic effect of all components of the film resulted in an excellent analytical performance of the proposed sensing assembly. This work provides a new direction to the progress and designing of nonenzymatic electrochemical sensors for pesticide determination in real samples.