RÉSUMÉ
Herein, a modified screen printed carbon electrode (SPCE) based on a composite material, graphene oxide-gold nanoparticles (GO-AuNPs), and poly(3-aminobenzoic acid)(P3ABA) for the detection of paraquat (PQ) is introduced. The modified electrode was fabricated by drop casting of the GO-AuNPs, followed by electropolymerization of 3-aminobenzoic acid to achieve SPCE/GO-AuNPs/P3ABA. The morphology and microstructural characteristics of the modified electrodes were revealed by scanning electron microscopy (SEM) for each step of modification. The composite GO-AuNPs can provide high surface area and enhance electroconductivity of the electrode. In addition, the presence of negatively charged P3ABA notably improved PQ adsorption and electron transfer rate, which stimulate redox reaction on the modified electrode, thus improving the sensitivity of PQ analysis. The SPCE/GO-AuNPs/P3ABA offered a wide linear range of PQ determination (10-9-10-4 mol/L) and low limit of detection (LOD) of 0.45 × 10-9 mol/L or 0.116 µg/L, which is far below international safety regulations. The modified electrode showed minimum interference effect with percent recovery ranging from 96.5% to 116.1% after addition of other herbicides, pesticides, metal ions, and additives. The stability of the SPCE/GO-AuNPs/P3ABA was evaluated, and the results indicated negligible changes in the detection signal over 9 weeks. Moreover, this modified electrode was successfully implemented for PQ analysis in both natural and tapped water with high accuracy.
Sujet(s)
Techniques électrochimiques , Électrodes , Or , Graphite , Nanoparticules métalliques , Paraquat , Graphite/composition chimique , Paraquat/analyse , Or/composition chimique , Nanoparticules métalliques/composition chimique , Techniques électrochimiques/méthodes , Limite de détection , Carbone/composition chimique , Polluants chimiques de l'eau/analyse , Herbicides/analyseRÉSUMÉ
Diquat (DQ) and paraquat (PQ) residues in food are potential hazards to consumers' health. Point-of-care testing (POCT) of them remains challenging. Based on surface-enhanced Raman spectroscopy (SERS) technology, we developed a POCT strategy for DQ and PQ on apple surface and in apple juice. A point-of-use composite was fabricated using a piece of porous melamine sponge (MS) modified with silver nanoflowers (AgNFs), combining the specificity of the SERS fingerprint and the excellent adsorption capacity of MS. Using this dual-functional AgNFs@MS, the on-site determination of the DQ and PQ residues was completed within 3 min without pretreatment. Clear trends were observed between SERS intensity and logarithmic concentrations, with r values from 0.962 to 0.984. The limit of detection of DQ and PQ were 0.14-0.70 ppb in apple juice and on apple surface. This study provides a new point-of-use alternative for rapidly detecting DQ and PQ residues in nonlaboratory settings.
Sujet(s)
Diquat , Contamination des aliments , Malus , Paraquat , Analyse sur le lieu d'intervention , Argent , Analyse spectrale Raman , Triazines , Argent/composition chimique , Paraquat/analyse , Triazines/analyse , Diquat/analyse , Diquat/composition chimique , Malus/composition chimique , Contamination des aliments/analyse , Analyse spectrale Raman/méthodes , Résidus de pesticides/analyse , Résidus de pesticides/composition chimique , Herbicides/analyse , Herbicides/composition chimique , Nanoparticules métalliques/composition chimique , Limite de détection , Jus de fruits et de légumes/analyseRÉSUMÉ
Paraquat (PQ) is a widely used and harmful herbicide that must be detected in the environment. This study reports a novel composite (CoS2-GCN) prepared by assembling cobalt disulfide (CoS2) derived from metal-organic frameworks (MOFs) on graphitic carbon nitride (GCN). An electrochemical sensor (CoS2-GCN/ glassy carbon electrode (GCE)) was successfully prepared by modifying CoS2-GCN onto a GCE to sensitively detect PQ. Different concentrations of PQ were detected using square-wave voltammetry, and the CoS2-GCN/GCE electrochemical sensor showed remarkable response signals for PQ in the range of 20 - 1000 nM and 1 - 13 µM, with a detection limit of 4.13 nM (S/N = 3). The CoS2-GCN/GCE electrochemical sensor exhibited high stability, reproducibility, and immunity to interference, which were attributed to the synergistic effects of CoS2 and GCN. In addition, the CoS2-GCN/GCE electrochemical sensor showed high applicability for the analysis of fruit samples. Therefore, the proposed sensor has potential applications in PQ detection.
Sujet(s)
Fruit , Graphite , Composés de l'azote , Paraquat , Paraquat/analyse , Reproductibilité des résultats , Fruit/composition chimique , Limite de détectionRÉSUMÉ
The synergy between eco-friendly biopolymeric films and printed devices leads to the production of plant-wearable sensors for decentralized analysis of pesticides in precision agriculture and food safety. Herein, a simple method for fabrication of flexible, and sustainable sensors printed on cellulose acetate (CA) substrates has been demonstrated to detect carbendazim and paraquat in agricultural, water and food samples. The biodegradable CA substrates were made by casting method while the full electrochemical system of three electrodes was deposited by screen-printing technique (SPE) to produce plant-wearable sensors. Analytical performance was assessed by differential pulse (DPV) and square wave voltammetry (SWV) in a linear concentration range between 0.1 and 1.0 µM with detection limits of 54.9 and 19.8 nM for carbendazim and paraquat, respectively. The flexible and sustainable non-enzymatic plant-wearable sensor can detect carbendazim and paraquat on lettuce and tomato skins, and also water samples with no interference from other pesticides. The plant-wearable sensors had reproducible response being robust and stable against multiple flexions. Due to high sensitivity and selectivity, easy operation and rapid agrochemical detection, the plant-wearable sensors can be used to detect biomarkers in human biofluids and be used in on-site analysis of other hazardous chemical substances.
Sujet(s)
Pesticides , Dispositifs électroniques portables , Humains , Pesticides/analyse , Paraquat/analyse , Sécurité des aliments , Agriculture , Eau/analyseRÉSUMÉ
The application of copper-based nanoparticles synthesized via green synthesis and their integration with a wearable electrode is reported for designing a flexible catalytic electrode on a glove for onsite electroanalysis of paraquat. A copper precursor and an orange extract from Citrus reticulata are used to synthesize an economical electrocatalytic material for supporting the selective and sensitive detection of paraquat. The electrode yields multidimensional fingerprints due to two redox couples in a square wave voltammogram, corresponding to the presence of paraquat. The developed lab-on-a-finger sensor provides the fast electroanalysis of paraquat within 10 s, covering a wide range from 0.50 to 1000 µM, with a low detection limit down to 0.31 µM and high selectivity. It is also possible to use this sensor at a fast scan rate as high as 6 V s-1 (< 0.5 s for a scan). This wearable glove sensor allows the user to directly touch and analyze samples, such as surfaces of vegetables and fruits, to screen the contamination. It is envisioned that these glove-embedded sensors can be applied to the on-site analysis of food contamination and environments.
Sujet(s)
Nanoparticules , Dispositifs électroniques portables , Cuivre , Paraquat/analyse , ÉlectrodesRÉSUMÉ
Herein, a novel surface molecularly imprinted-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (SMI-MALDI-TOF MS) method for direct target paraquat (PQ) analysis in complicated samples is reported. Notably, a captured analyte-imprinted material can be directly detected via MALDI-TOF MS by using imprinted material as nanomatrix. Using this strategy, the molecular specific affinity performance of surface molecularly imprinted polymers (SMIPs) and the high-sensitivity detection capability of MALDI-TOF MS was integrated. The introduction of SMI endowed the nanomatrix with the capacity for rebinding the target analyte and ensuring specificity, prevented the interfering organic matrix, and enhanced the analyzing sensitivity. By using paraquat (PQ) as a template, dopamine as a monomer, and covalent organic frameworks with a carboxyl group (C-COFs) as a substrate, polydopamine (PDA) was decorated on C-COFs via a simple self-assembly procedure to generate an analyte-based surface molecularly imprinted polymer (C-COF@PDA-SMIP), which served the dual function of SMIP capturing the target analytes and high-efficiency ionization. Thus, a reliable MALDI-TOF MS detection PQ with high selectivity and sensitivity as well as an interference-free background was achieved. The synthesis and enrichment conditions of C-COF@PDA-SMIPs were optimized, and its structure and property were characterized. Under optimal experimental conditions, the proposed method achieved highly selective and ultrasensitive detection of PQ from 5 to 500 pg mL-1, and the limit of detection was as low as 0.8 pg mL-1, which is at least three orders of magnitude lower than that achieved without enrichment. In addition, the specificity of the proposed method was superior to that of C-COFs and nonimprinted polymers. Moreover, this method exhibited reproducibility, stability, and high salt tolerance. Lastly, the practical applicability of the method was successfully verified by analyzing complicated samples, such as grass and orange.
Sujet(s)
Empreinte moléculaire , Spectrométrie de masse MALDI , Paraquat/analyse , Paraquat/composition chimique , Spectrométrie de masse MALDI/méthodes , Empreinte moléculaire/méthodes , LasersRÉSUMÉ
Pesticides are heavily employed compounds protecting crops, however, these compounds can be extremely harmful to human health. Once the monitoring of pesticides in foods is of great importance, in this work we propose a ready-to-use electrochemical sensor made with 3D printing technology, capable of detecting paraquat and carbendazim in sequential analysis. The proposed electrodes are lab-made and of easy obtention, composed of graphite on a polylactic acid matrix, and provided great results for the analysis of paraquat and carbendazim in honey, milk, juice, and water samples. The sequential analysis of paraquat and carbendazim was proposed, providing optimal analysis of both compounds individually when both are present in a mixture. Limits of detection of 0.01 and 0.03 µmol/L for paraquat and carbendazim, respectively. Recovery tests attested to the suitability of the method, ranging from 94.5 to 113.7 %, and the suitability of 3D printing for environmental and food samples analysis.
Sujet(s)
Graphite , Pesticides , Humains , Paraquat/analyse , Graphite/composition chimique , Benzimidazoles , Électrodes , Pesticides/analyse , Techniques électrochimiques/méthodesRÉSUMÉ
BACKGROUND: In modern animal husbandry, breeders pay increasing attention to improving sow nutrition during pregnancy and lactation to favor the health of neonates. Sow milk is a main food source for piglets during their first three weeks of life, which is not only a rich repository of essential nutrients and a broad range of bioactive compounds, but also an indispensable source of commensal bacteria. Maternal milk microorganisms are important sources of commensal bacteria for the neonatal gut. Bacteria from maternal milk may confer a health benefit on the host. METHODS: Sow milk bacteria were isolated using culturomics followed by identification using 16S rRNA gene sequencing. To screen isolates for potential probiotic activity, the functional evaluation was conducted to assess their antagonistic activity against pathogens in vitro and evaluate their resistance against oxidative stress in damaged Drosophila induced by paraquat. In a piglet feeding trial, a total of 54 newborn suckling piglets were chosen from nine sows and randomly assigned to three treatments with different concentrations of a candidate strain. Multiple approaches were carried out to verify its antioxidant function including western blotting, enzyme activity analysis, metabolomics and 16S rRNA gene amplicon sequencing. RESULTS: The 1240 isolates were screened out from the sow milk microbiota and grouped into 271 bacterial taxa based on a nonredundant set of 16S rRNA gene sequencing. Among 80 Pediococcus isolates, a new Pediococcus pentosaceus strain (SMM914) showed the best performance in inhibition ability against swine pathogens and in a Drosophila model challenged by paraquat. Pretreatment of piglets with SMM914 induced the Nrf2-Keap1 antioxidant signaling pathway and greatly affected the pathways of amino acid metabolism and lipid metabolism in plasma. In the colon, the relative abundance of Lactobacillus was significantly increased in the high dose SMM914 group compared with the control group. CONCLUSION: P. pentosaceus SMM914 is a promising probiotic conferring antioxidant capacity by activating the Nrf2-Keap1 antioxidant signaling pathway in piglets. Our study provided useful resources for better understanding the relationships between the maternal microbiota and offspring. Video Abstract.
Sujet(s)
Antioxydants , Lait , Animaux , Antioxydants/analyse , Antioxydants/métabolisme , Bactéries , Drosophila/génétique , Drosophila/métabolisme , Femelle , Protéine-1 de type kelch associée à ECH/analyse , Protéine-1 de type kelch associée à ECH/métabolisme , Facteur-2 apparenté à NF-E2/génétique , Facteur-2 apparenté à NF-E2/métabolisme , Paraquat/analyse , Paraquat/métabolisme , Pediococcus pentosaceus/génétique , Pediococcus pentosaceus/métabolisme , Grossesse , ARN ribosomique 16S/analyse , SuidaeRÉSUMÉ
The abuse of pesticides has introduced a large number of residues in soil and drinking water, which can then enter the food chain and the human body. Monitoring pesticide residues and developing simple and fast detection systems for pesticide residues is urgently needed. In this study, we presented one-pot prepared CdS fluorescent quantum dots (QDs) and explored their sensing application for organic pesticides. The CdS QDs can sensitively and selectively detect three different pesticides, dichlorvos (DDVP), paraquat, and glufosinate-ammonium, through different fluorescence responses. Paraquat can effectively quench the fluorescence of the QDs and DDVP can cause remarkable fluorescent enhancement. Glufosinate-ammonium can induce both 150 nm fluorescent blueshifting and 30-fold fluorescent enhancement. The probe exhibited low detection limits for the three pesticides: 1.44 µM for paraquat, 0.23 mM for DDVP, and 49.8 µM for glufosinate-ammonium. Furthermore, based on the results, we utilized the powerful functions of smartphones to establish a concentration-gray value standard curve through RGB values and gray values to realize the qualitative detection and quantitative analysis of DDVP. It is believed that this work presents a new platform for the simultaneous detection of multiple pesticides using a single QDs probe. The present on-site method using a smartphone is of great potential for water monitoring in rural areas.
Sujet(s)
Eau de boisson , Résidus de pesticides , Pesticides , Boîtes quantiques , Dichlorvos/analyse , Eau de boisson/analyse , Colorants fluorescents/composition chimique , Humains , Paraquat/analyse , Résidus de pesticides/analyse , Pesticides/analyse , Boîtes quantiques/composition chimique , Spectrométrie de fluorescence/méthodesRÉSUMÉ
A sensitive nanopipette sensor is established through a unique design of host-guest recognition, which could be further enhanced by the introduction of gold nanoparticles (Au NPs). Generally, the nanopipette is conjugated with caboxylatopillar[5]arenes (CP[5]) or carboxylated leaning pillar[6]arene (CLP[6]) to generate recognition sites. After the addition of pesticide molecules, they would be captured by CP[5] (or CLP[6]), resulting in a significant electronegativity change on the nanopipette's inner surface, which could be determined by the ionic current change. The CP[5]-modified nanopipette exhibited reliable selectivity for paraquat, while the CLP[6]-modified nanopipette showed an ability of detection for both paraquat and diquat. The addition of Au NPs improved the selectivity and sensitivity of the CP[5]-Au NP-modified nanopipette for paraquat sensing. After optimization by lowering the size of the Au NPs, CP[5]-Au NPs (3 nm)-modified nanopipettes achieved lower detection limits of 0.034 nM for paraquat. Furthermore, in real sample analysis, this sensor demonstrates exceptional sensitivity and selectivity. This study provides a new strategy to develop nanopipette sensors for practical small molecule detection. The gold nanoparticles enhanced quartz nanopipette sensor based on host-guest interaction was firstly established, which could achieve an excellent limit of detection of 3.4 × 10-11 mol/L for paraquat.
Sujet(s)
Or , Nanoparticules métalliques , Techniques électrochimiques , Or/composition chimique , Nanoparticules métalliques/composition chimique , Paraquat/analyseRÉSUMÉ
An in vivo microcapillary sampling (MCS) method coupled with matrix-assisted laser desorption/ionization fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR-MS) analysis was utilized to monitor the real-time bipyridine quaternary ammonium herbicides concentrations and assess their uptake and elimination behaviors in living cabbage plants noninvasively. Under optimized conditions, the proposed method for paraquat (PQ) and diquat (DQ) determination showed wide linear ranges (7.81-500 µg/kg), low limits of detection (0.1-0.9 µg/kg), and good reproducibility. In vivo tracking results demonstrated that different absorption behaviors between PQ and DQ existed in living vegetables and DQ was more easily absorbed. Through decay kinetics model fitting, herbicide half-lives were 1.32 and 1.86 days for PQ and DQ, respectively. To summarize, in vivo MCS method provides valuable information on herbicide risks for agricultural production, which is suitable for temporal, spatial, and longitudinal studies in the same living system and multicompartmental studies in the same organism.
Sujet(s)
Diquat , Herbicides , Cyclotrons , Diquat/analyse , Analyse de Fourier , Herbicides/analyse , Lasers , Paraquat/analyse , Reproductibilité des résultats , Spectrométrie de masse MALDI , LégumesRÉSUMÉ
The incidence of paraquat poisoning has significantly decreased with the addition of odorizer and emetics to the liquid concentrate. Paraquat poisonings are usually attributed to suicidal and accidental or occupational exposure. Here, we report an unusual fatal case of homicidal paraquat poisoning. An intoxicated, a 37-year-old man consumed a mixture of white wine and paraquat prepared by his wife. This resulted in intermittent vomiting, which he attributed to being intoxicated. The man was admitted to the hospital for treatment 3 days later. Due to the lack of knowledge of paraquat exposure, the man did not receive effective treatment and died of respiratory failure 22 days later. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was applied to detect paraquat in 16 postmortem specimens: kidney (1.31 ug/g), urine (0.91 ug/ml), liver (0.62 ug/g), lung (0.39 ug/g), muscle (0.35 ug/g), bile (0.32 ug/ml), heart (0.28 ug/g), brain (0.22 ug/g), pancreas (0.22 ug/g), spleen (0.18 ug/g), cardiac blood (0.15 ug/ml), cerebrospinal fluid (0.14 ug/ml), pericardial effusion (0.12 ug/ml), pleural effusion (0.09 ug/ml), peripheral blood (0.08 ug/ml), and vitreous humor (0.06 ug/ml). The highest concentration of paraquat was detected in the kidney followed by the urine in all tissues and body fluids. At present, although the cases of paraquat poisoning have decreased, the high mortality rate resulting from its irreversible lung damage and respiratory failure makes paraquat poisoning, especially occult paraquat poisoning, still needs to be carefully identified in forensic practice and clinical diagnosis.
Sujet(s)
Intoxication , Toxiques , Insuffisance respiratoire , Adulte , Humains , Foie/composition chimique , Mâle , Paraquat/analyse , Toxiques/analyse , Spectrométrie de masse en tandemRÉSUMÉ
Objective: To establish a LC-MS/MS method for determination of paraquat and diquat in plasma and urine samples. Methods: Plasma is precipitated by acetonitrile then diluent with phosphate buffer (pH=7) , urine is diluent with phosphate buffer (pH=7) , then diluent samples extracted with Oasis WCX solid-phase extraction column. Samples were analyzed using LC-MS/MS in multiple reaction monitoring (MRM) mode. The analytical column was XBridge®BEH-HILIC (100 mm×2.1 mm×2.5 µm) and the mobile phase were 100 mmol ammonium formate add 0.5% formic acid and acetonitrile. Paraquat was quantified by internal standard method and diquat by external standard method. Results: The calibration curves of paraquat and diquat were linear in the concentration range of 10.0~120.0 µg/L, the correlation coefficient (r) were 0.9985~0.9994. The limit of detection of paraquat in plasma and urine were 1.98 µg/L and 1.00 µg/L, respectively, the recovery rate were 100.2%~107.3%, the RSD were 1.6%~3.3%. The limit of detection of diquat in plasma and urine were 1.80 µg/L and 2.77 µg/L, respectively, the recovery rate were 85.3%~93.1%, the RSD were 1.8%~5.5%. Conclusion: This method is sensitive and accurate, and can simultaneously determine paraquat and diquat in plasma and urine.
Sujet(s)
Diquat , Paraquat , Chromatographie en phase liquide à haute performance , Chromatographie en phase liquide , Paraquat/analyse , Extraction en phase solide , Spectrométrie de masse en tandemRÉSUMÉ
This study aimed to develop an aptasensor for paraquat detection by gold nanoparticles. The specific aptamer for paraquat was selected by using the SELEX process via capillary electrophoresis. Sixty-three aptamer candidates were amplified by asymmetric PCR and screened for paraquat binding using gold nanoparticles (AuNPs). Aggregation of AuNPs was specifically induced by desorption of paraquat binding aptamers from the surface of AuNPs as a result of aptamer-target interaction leading to the color change from red to purple. Aptamer 77F with the following sequence: 5'-AGGCTTACACCTGAAAAGCGGCTTAATTTACACTACTGTAT-3' was selected as a highly specific aptamer for paraquat. The detection limit of paraquat was 0.267 µg/mL by colorimetry and 1.573 µg/mL by the quartz crystal microbalance (QCM) technique. This aptamer showed specificity for paraquat by colorimetry. Dimethyl phophite, diethyl phophite and O,O diethyl thiophosphate potassium salt did not react by colorimetry but, exhibited a weak nonspecific reaction by QCM. This is first time that an aptasensor was used for detection of paraquat based on QCM. However, the aptasensor based on the colorimetric method simply uses a generation of a signal that can be detected by the naked eye. This technique is rapid, low cost easy to use and suitable for on-site detection of herbicide residue.
Sujet(s)
Aptamères nucléotidiques/composition chimique , Colorimétrie/méthodes , Paraquat/analyse , Aptamères nucléotidiques/génétique , Aptamères nucléotidiques/métabolisme , Techniques de biocapteur/méthodes , Colorimétrie/instrumentation , Électrophorèse capillaire , Or/composition chimique , Herbicides/analyse , Limite de détection , Nanoparticules métalliques/composition chimique , Paraquat/métabolisme , Réaction de polymérisation en chaîne , Techniques de microbalance à cristal de quartz/méthodes , Sensibilité et spécificitéRÉSUMÉ
Paraquat is one of the most toxic materials widely applied in agriculture in most countries. In the present study, a simple, innovative and inexpensive nano biosensor which is based on a thioglycolic acid (TGA) - CdTe@CdS core-shell nanocrystals (NCs) to detect paraquat, is suggested. The NCs based biosensor shows a linear working range of 10-100 nM, and limited detection of 3.5 nM. The proposed sensor that has been well used for the detection and determination of paraquat in natural water samples is collected from corn field and a canal located near to the corn field yielding recoveries as high as 98%. According to our findings, the developed biosensor shows reproducibility and high sensitivity to determine paraquat in natural water samples in which the amount of paraquat has low levels. The suggested method is efficiently applied to paraquat determination in the samples of natural water that are collected from a tap water and a canal located near to the cornfield.
Sujet(s)
Colorants fluorescents/composition chimique , Nanoparticules/composition chimique , Paraquat/analyse , Polluants chimiques de l'eau/analyse , Techniques de biocapteur , Composés du cadmium/composition chimique , Concentration en ions d'hydrogène , Sulfates/composition chimique , Tellure/composition chimique , Thioglycolates/composition chimiqueRÉSUMÉ
The contamination of paraquat (1,1'-dimethyl-4,4'-bipyridylium dichloride) herbicide from the farming area has become a public concern in many countries. This herbicide harms to human health and negatively effects the soil fertility. Several methods have been introduced for the remediation of paraquat. In this study, 20 isolates of the paraquat-tolerant fungi were isolated from the contaminated soil samples in northern Thailand. We found that isolate PRPY-2 and PFCM-1 exhibited the highest degradation activity of paraquat on synthetic liquid medium. About 80 and 68% of paraquat were removed by PRPY-2 and PFCM-1 respectively after 15 days of cultivation. Based on the morphological characteristic and molecular analysis, the fungal isolate PRPY-2 and PFCM-1 were identified as Aspergillus tamarii and Cunninghamella sp. respectively. The biosorption of paraquat on these fungal mycelia was also investigated. It was found that only 8-10% of paraquat could be detected on their mycelia, while 24-46% of paraquat was degraded by fungal mycelia. This is the first report on paraquat degrading ability by A. tamarii and Cunninghamella sp. It is demonstrated that these filamentous fungi are promising microorganisms available for remediation of paraquat contaminated environment.
Sujet(s)
Aspergillus/métabolisme , Dépollution biologique de l'environnement , Cunninghamella/métabolisme , Herbicides/métabolisme , Paraquat/métabolisme , Polluants du sol/métabolisme , Agriculture , Aspergillus/isolement et purification , Cunninghamella/isolement et purification , Humains , Paraquat/analyse , Sol/composition chimique , Microbiologie du sol , Polluants du sol/analyse , ThaïlandeRÉSUMÉ
A nanocomposite based on nanofibrillar cellulose (NFC) coated with gold-silver (core-shell) nanoparticles (Au@Ag NPs) was developed as a novel surface-enhanced Raman spectroscopy (SERS) substrate. SERS performance of NFC/Au@Ag NP nanocomposite was tested by 4-mercaptobenzoic acid. The cellulose nanofibril network was a suitable platform that allowed Au@Ag NPs to be evenly distributed and stabilized over the substrate, providing more SERS hotspots for the measurement. Two pesticides, thiram and paraquat, were successfully detected either individually or as a mixture in lettuce by SERS coupled with the nanocomposite. Strong Raman scattering signals for both thiram and paraquat were obtained within a Raman shift range of 400-2000 cm-1 and a Raman intensity ~ 8 times higher than those acquired by NFC/Au NP nanocomposite. Characteristic peaks were clearly observable in all SERS spectra even at a low concentration of 10 µg/L of pesticides. Limit of detection values of 71 and 46 µg/L were obtained for thiram and paraquat, respectively. Satisfactory SERS performance, reproducibility, and sensitivity of NFC/Au@Ag NP nanocomposite validate its applicability for real-world analysis to monitor pesticides and other contaminants in complex food matrices within a short acquisition time. Graphical abstract.
Sujet(s)
Cellulose/composition chimique , Lactuca/composition chimique , Nanoparticules métalliques/composition chimique , Nanocomposites/composition chimique , Paraquat/analyse , Thirame/analyse , Or/composition chimique , Limite de détection , Pesticides/analyse , Reproductibilité des résultats , Argent/composition chimique , Analyse spectrale RamanRÉSUMÉ
Simple and traditional hydrothermal fabrication of a novel balsam pear-shaped CuO with high SERS enhancement is presented. XRD (X-ray diffraction), SEM (scanning electronic microscopy), TEM (transmission electron microscope), HRTEM (high-resolution transmission electron microscope), UV-Vis, and Raman are adopted to ensure that this balsam pear-shaped CuO with dense nanoparticle protuberance is successfully prepared. The LOD of this CuO SERS substrate is 4.79 µg L-1 with R6G as molecular probe. By using DFT (density functional theory) calculation and FDTD (finite difference time domainmethod) simulation, both EM (electromagnetic enhancement) and CM (chemical enhancement) mechanisms are investigated, and the results show that these two-enhancement mechanisms can coexist in this balsam pear-shaped CuO. Finally, the prepared substrate has been applied for the determination of trace levels of paraquat in solution , and results show that its LOD for paraquat is 275 µg L-1 (optimum Raman band: 1646 cm-1 Raman shift), which is better than the government standard in China. A dexterous and facile way for fabrication of CuO SERS-active substrates with low cost and high performance, quite promising in detection of chemically hazardous substances and pesticide residue is provided. Graphical abstract.
Sujet(s)
Cuivre/composition chimique , Herbicides/analyse , Nanoparticules métalliques/composition chimique , Paraquat/analyse , Limite de détection , Résidus de pesticides/analyse , Analyse spectrale RamanRÉSUMÉ
Paraquat (PQ) poisoning is a serious threat to human health that leads to pulmonary toxicity, neurotoxicity, and inflammation. Protecting humans from PQ exposure requires the development of rapid analytical methods for on-site detection. Here, two monoclonal antibodies against PQ were generated and an immunochromatographic assay (ICA) was exploited to determine PQ concentrations in water samples. The results showed that the monoclonal antibody 1D6 exhibited higher affinity and sensitivity, with an affinity constant of 5.4 × 108 mol/L and a limit of detection as low as 0.02 ng/mL. Without sample pretreatment, the developed ICA method provided visible limits of detection ranging from 0.25 to 1 ng/mL, and cut-off limits ranging from 1 to 5 ng/mL, where average recoveries were between 83.15% ± 1.9% and 94.49% ± 2.45% with a coefficient of variation ranging from 1.40% to 7.37%. Importantly, these observations were consistent with liquid chromatography tandem mass spectrometry. These data and results suggested that the ICA method was a reliable, portable, and high-throughput method for determining PQ residues in water samples.
Sujet(s)
Anticorps monoclonaux/immunologie , Dosage immunologique/méthodes , Paraquat/analyse , Pollution chimique de l'eau/analyse , Or/composition chimique , Haptènes/composition chimique , Humains , Limite de détection , Nanoparticules métalliques/composition chimique , Paraquat/composition chimique , Paraquat/immunologieRÉSUMÉ
Paraquat (1,10-dimethyl-4,40-dipyridinium chloride), also known as methyl viologen, is widely used as a quaternary ammonium herbicide (broadleaf weed killer) all over the world owing to its excellent effect in plant cells for crop protection and horticultural use. However, it is dangerous because of its high acute toxicity even at low concentrations. Its detection in the environment is therefore necessary. As a consequence of its widespread usage, it causes genotoxic, teratogenic as well as other environmental and ecological adverse impacts. Exposure to PQ leads to a high mortality rate because no specific drug is effective for treatment. Excessive consumption of PQ can cause cellular damage and necrosis in the brain, heart, lungs, liver, and kidneys. The diversity and sensitivity of the analyses currently required have forced the experimenter to use more advanced and efficient techniques, which can provide qualitative and quantitative results in complex environments. Electrochemical methods generally meet these criteria while offering other advantages to achieve excellent accuracy and fast handling. This paper provides an overview of the determination of PQ using electrochemical methods combined with several modified electrodes in food samples, including milk, apple juice, tomato juice, and potato juice. Emphasis was placed on the most relevant modifiers used to generate high selectivity and sensitivity such as noble metals, metallic nanoparticles, polymers, biomolecules, clay, and apatite minerals. Comprehensively, it is strongly convincing that the synergy between the sensor substrate and the modifier architecture gives the electrodes a high capacity to detect paraquat in complex matrices such as food. In line with the context, information's on the mechanism of electrooxidation or reduction of PQ has been reported with the discussion of some future prospects and some insights. To the best of our knowledge, there is no review article relating the electrochemical determination of paraquat.