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Biosensors & Bioelectronics Mar 2022Large-area surface-enhanced Raman spectroscopy (SERS) sensing platforms displaying ultrahigh sensitivity and signal uniformity have potentially enormous sensing...
Large-area surface-enhanced Raman spectroscopy (SERS) sensing platforms displaying ultrahigh sensitivity and signal uniformity have potentially enormous sensing applicability, but they are still challenging to prepare in a scalable manner. In this study, silver nanopaste (AgNPA) was employed to prepare a wafer-scale, ultrasensitive SERS substrate. The self-generated, high-density Ag nanocracks (NCKs) with small gaps could be created on Si wafers via a spin-coating process, and provided extremely abundant hotspots for SERS analyses with ultrahigh sensitivity-down to the level of single molecules (enhancement factor: ca. 10; detection limit: ca. 10 M)-and great signal reproducibility (variation: ca. 3.6%). Moreover, the Ag NCK arrays demonstrated broad applicability and practicability for on-site detection when combined with a portable 785 Raman spectrometer. This method allowed the highly sensitive detection of a diverse range of analytes (benzo[a]pyrene, di-2-ethylhexyl phthalate, aflatoxins B1, zearalenone, ractopamine, salbutamol, sildenafil, thiram, dimethoate, and methamidophos). In particular, pesticides are used extensively in agricultural production. Unfortunately, they can affect the environment and human health as a result of acute toxicity. Therefore, the simultaneous label-free detection of three different pesticides was demonstrated. Finally, the SERS substrates are fabricated through a simple, efficient, and scalable process that offers new opportunities for mass production.
Topics: Biosensing Techniques; Humans; Metal Nanoparticles; Reproducibility of Results; Silver; Spectrum Analysis, Raman; Thiram
PubMed: 34973566
DOI: 10.1016/j.bios.2021.113920 -
Toxicology Reports Jun 2024Methamidophos is a highly hazardous organophosphate and is known to cause an acute cholinergic toxidrome. Methamidophos use is not allowed in South Africa and therefore...
Methamidophos is a highly hazardous organophosphate and is known to cause an acute cholinergic toxidrome. Methamidophos use is not allowed in South Africa and therefore local data pertaining to methamidophos poisoning is very limited, with no paediatric clinical cases described. Methamidophos is an active metabolite of acephate, a commonly used organophosphate, registered for agricultural use in South Africa. We present a paediatric case of methamidophos poisoning with prolonged clinical effects. The patient experienced a prolonged cholinergic toxidrome lasting 10 days, with a period of near-full recovery during this time. We discuss the biological plausibility of the detected methamidophos being a byproduct of acephate. In addition, we highlight the importance of closer monitoring of patients with organophosphate poisoning in areas where acephate is commonly used.
PubMed: 38173652
DOI: 10.1016/j.toxrep.2023.12.001 -
International Journal of Environmental... Dec 2016Methamidophos is a representative organophosphate insecticide. The knowledge of its developmental neurotoxicity is limited, especially for zebrafish in the early stages...
Methamidophos is a representative organophosphate insecticide. The knowledge of its developmental neurotoxicity is limited, especially for zebrafish in the early stages of their life. Four hour post-fertilization (hpf) zebrafish embryos were exposed to several environmentally relevant concentrations of methamidophos (0, 25, and 500 μg/L) for up to 72 hpf. Locomotor behavior was then studied in the zebrafish larvae at this timepoint. Acridine orange (AO) staining was carried out in the zebrafish larvae, and the mRNA levels of genes associated with neural development ( and ) were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The number of escape responders for mechanical stimulation was significantly decreased in exposed groups. AO staining showed noticeable signs of apoptosis mainly in the brain. In addition, the mRNA levels of and were both significantly down-regulated in exposed groups. Our study provides the first evidence that methamidophos exposure can cause developmental neurotoxicity in the early stages of zebrafish life, which may be caused by the effect of methamidophos on neurodevelopmental genes and the activation of cell apoptosis in the brain.
Topics: Animals; Apoptosis; Embryo, Nonmammalian; Gene Expression Regulation, Developmental; Insecticides; Larva; Neurotoxicity Syndromes; Organophosphorus Compounds; Organothiophosphorus Compounds; RNA, Messenger; Zebrafish
PubMed: 28036051
DOI: 10.3390/ijerph14010023 -
Food Additives & Contaminants. Part B,... Dec 2021This study reports a surveillance of multi-pesticide residues of fruits and vegetables sold in the local markets carried out in 2018-2019 in Botswana to access consumer...
This study reports a surveillance of multi-pesticide residues of fruits and vegetables sold in the local markets carried out in 2018-2019 in Botswana to access consumer safety. A validated method for analysis of 232 pesticide residues in fruits and vegetables was applied, based on QuEChERS-GC-MS/MS methodology. A total of 83 fruit and vegetable sold in different markets were bought from three different areas of the southern region . Levels of pesticides ranged between 0.0032 ± 0.0009 mg/kg and 70.4 ± 19.4 mg/kg. A total of 78% of the samples contained pesticide residues, whereas only 13% of the samples violated the EU/Codex MRLs. In particular, rape vegetable samples exceeded legislative limits most, followed by cabbage, green pepper and tomato. The most frequently detected compounds were chlopyrifos, chlorfenapyr, tebuconazole, methamidophos and cypermethrin. These results will serve as a foundation for future studies, involving continuous monitoring programmes.
Topics: Botswana; Food Contamination; Fruit; Pesticide Residues; Tandem Mass Spectrometry; Vegetables
PubMed: 34266362
DOI: 10.1080/19393210.2021.1950845 -
Environmental Science and Pollution... Oct 2021Since the invasion of the fall armyworm moth (Spodoptera frugiperda) in China in January 2019, damage to maize crops has gradually intensified, and chemical control has...
Since the invasion of the fall armyworm moth (Spodoptera frugiperda) in China in January 2019, damage to maize crops has gradually intensified, and chemical control has become the main control measure. This study aimed to examine methods of effective pest control while monitoring the environmental impact of pesticide use. The effectiveness of S. frugiperda pest control by foliar spraying and root irrigation of maize plants with acephate was determined, and the absorption, distribution, and dissipation of acephate and methamidophos by maize were studied. Field trials showed that acephate treatment at 6000 g a.i. ha was the most effective for controlling S. frugiperda. Acephate and methamidophos were absorbed from the roots, transported upward, and concentrated in the leaves, particularly new leaves. The terminal residues of acephate and methamidophos in maize grains were below detectable levels at 60 days after treatment. The results demonstrate that acephate treatment via root irrigation can more effectively control the infestation of S. frugiperda in maize than acephate treatment via foliar spraying. The translocation and distribution of acephate and methamidophos by root irrigation were more uniform, and the holding efficiency was higher than those in foliar spraying, suggesting an extended period of control efficacy. This pest control method could be utilized to reduce pesticide residues while safely and efficiently controlling S. frugiperda infestation.
Topics: Animals; Moths; Organothiophosphorus Compounds; Phosphoramides; Spodoptera; Zea mays
PubMed: 34091843
DOI: 10.1007/s11356-021-14689-6 -
The Science of the Total Environment Feb 2022Enantioselective metabolism of chiral pesticide in plants is very important. In vitro system has become an effective means to study the metabolism of pesticides in...
Enantiomer metabolism of acephate and its metabolite methamidophos in in vitro tea (Camellia sinensis L.) systems: Comparison between cell suspensions and excised tissues.
Enantioselective metabolism of chiral pesticide in plants is very important. In vitro system has become an effective means to study the metabolism of pesticides in plants, but the study on the metabolism of chiral pesticides has not been reported. This work compared the enantiomer metabolic behavior of acephate and its metabolite methamidophos between tea cell suspensions and excised tea stem with leaves. (±)-Acephate could be absorbed and transferred well to top leaves by the cut end of excised stem after 24 h. (±)-Methamidophos was derived from the metabolism of (±)-acephate in tea plants at 3-5% in leaves and 2-3% in stems at 216 h. The content of (+)-methamidophos was 1.5 times higher than that of (-)-methamidophos in excised leaves. Though both (±)-acephate and (±)-methamidophos could be metabolized well by cell suspension, (±)-acephate and (±)-methamidophos was non-enantioselectively metabolized in cell suspension. It was shown that using the excised tea stem with leaves for chiral pesticide metabolism studies was much closer to intact plant than cell suspensions. This result also established an effective and easily available in vitro metabolic model for the study of enantioselective metabolism of chiral contaminants from environment.
Topics: Camellia sinensis; Insecticides; Organothiophosphorus Compounds; Phosphoramides; Plant Leaves; Stereoisomerism; Suspensions; Tea
PubMed: 34626633
DOI: 10.1016/j.scitotenv.2021.150863 -
Analytical Methods : Advancing Methods... Feb 2022Herein, an ionic-liquid-based effervescence-enhanced magnetic solid-phase extraction (ILE-MSPE) approach for the extraction/concentration of organophosphorus pesticides...
Herein, an ionic-liquid-based effervescence-enhanced magnetic solid-phase extraction (ILE-MSPE) approach for the extraction/concentration of organophosphorus pesticides in waters is reported with high stability and portability for rapid sample pretreatment in the field. The ionic-liquid-based magnetic effervescent tablet, composed of magnetic nanoparticles (FeO), sodium carbonate (NaCO) as an alkaline source, and an ionic liquid ([CMIM][PF]), played triple functions: extractant, dispersant, and retrieving agent. Based on the one-factor-at-a-time method, the important variables for the ILE-MSPE approach were optimized as follows: as an extractant, 70 μL of [CMIM][PF]; molar ratio of alkaline to acidic sources (NaCO : HCHO) as 1 : 1; and mass of magnetic nanoparticles (MNPs) of 30 mg. By integrating HPLC-DAD detection, the ILE-MSPE approach offered the limits of detection of 0.14-0.22 μg L and fortified recoveries of 81.4-97.6% for three representative species (methamidophos, phoxim, and parathion) in water samples. The relative standard deviations were lower than 4.9% for both the intra-day and inter-day precision. Overall, the newly developed method is environmentally benign, time-saving, and feasible for outdoor application.
Topics: Ionic Liquids; Magnetic Phenomena; Organophosphorus Compounds; Pesticides; Solid Phase Extraction; Water
PubMed: 35084403
DOI: 10.1039/d1ay01698a -
Analytical Chemistry Jul 2023Detection of organophosphorus pesticides (OPs) with high sensitivity in environmental samples is of vital importance for environmental safety and human health. However,...
Detection of organophosphorus pesticides (OPs) with high sensitivity in environmental samples is of vital importance for environmental safety and human health. However, it remains a challenge to achieve fM (10 mol/L) sensitivity for detecting OPs. Herein, we developed an acetylcholinesterase sensor based on 3,3',5,5'-tetramethylbenzidine (TMB) combining an enzyme-mediated strategy and scanning tunneling microscopy break junction (STM-BJ). Benefiting from the enzyme inhibition kinetics of OPs and the customized spectral clustering analysis method, our new strategy achieved the detection of methamidophos (MTMP) with a limit of 10 aM (10 mol/L) and 3 times higher selectivity in mixed OPs. As applied to natural lake waters, it also exhibited high reproducibility, high stability, and good recovery. This work paves a new avenue toward the application of single-molecule conductance characterizations for biochemical analysis and environmental monitoring.
Topics: Humans; Pesticides; Organophosphorus Compounds; Acetylcholinesterase; Reproducibility of Results; Biosensing Techniques
PubMed: 37347983
DOI: 10.1021/acs.analchem.3c00691 -
Forensic Science International Jul 2019We herein report an intoxication case caused by the ingestion of the pesticide Ortoran, which consists of 50% acephate aqueous solution. A man in his 60 s was found...
We herein report an intoxication case caused by the ingestion of the pesticide Ortoran, which consists of 50% acephate aqueous solution. A man in his 60 s was found dead in his car with a 100-mL bottle containing approximately 50 mL of Ortoran. In a gas chromatography - mass spectrometry (GC-MS) screening test, acephate and its metabolite methamidophos were qualitatively detected in his stomach contents. The amounts of acephate and methamidophos (μg/g) in the extract of each body fluid or organ tissue were measured using GC-MS and were as follows: 35.8, 2.84 (heart blood); 44.0, 2.26 (peripheral blood); 2,240, 2.79 (urine); 53.1, 8.91 (brain occipital lobe); 43.7, 2.95 (liver); 102.3, 8.02 (right kidney); and 5450, 22.9 (stomach contents). Based on these results and autopsy findings, the cause of death was concluded to be acute fatal intoxication caused by the pesticide containing acephate and its active metabolite, methamidophos. Concentration ratios between acephate and methamidophos in each body fluid and organ tissue showed higher relative concentrations of brain methamidophos to acephate than those of other organ tissues. A high relative concentration of brain methamidophos may contribute to the intoxication of acephate in humans.
Topics: Brain Chemistry; Gas Chromatography-Mass Spectrometry; Gastrointestinal Contents; Humans; Insecticides; Kidney; Liver; Lung; Male; Middle Aged; Organothiophosphorus Compounds; Phosphoramides; Tissue Distribution
PubMed: 31000354
DOI: 10.1016/j.forsciint.2019.02.015 -
Integrated Environmental Assessment and... Sep 2022Intact soil food webs are pivotal to maintaining essential soil functions, such as carbon recycling, sequestering, and biomass production. Although the functional role...
Intact soil food webs are pivotal to maintaining essential soil functions, such as carbon recycling, sequestering, and biomass production. Although the functional role of micro- (e.g., bacteria and fungi) and macrofauna (e.g., earthworms) is comparatively well established, the importance of the mesofauna community (e.g., abundance and diversity of Acari and Collembola) in maintaining soil functionality is less clear. We investigated this question in a six-month field experiment in arable soil by actively manipulating mesofauna abundance and biodiversity through the application of two legacy insecticides (lindane and methamidophos) at sufficiently high doses to reduce mesofauna abundance (well above previously registered application rates; 2.5 and 7.5 kg a.s./ha for lindane, and 0.6 and 3 kg a.s./ha for methamidophos) and measure the impact on organic matter degradation. Our results demonstrate that both insecticides had reduced Collembola and Acari abundances by up to 80% over the study's six-month duration. In addition, we observed less pronounced and more complex changes in mesofauna biodiversity over time. These included insecticide-dependent temporal fluctuations (both reduction and increase) for different estimates (indices) of local (alpha)-diversity over time and no lasting impact for most estimates after six months. Even at these exceptionally high field rates, Collembola and Acari diversity was observed to generally recover by six months. In contrast, considering organic matter breakdown, we found no evidence of a treatment-related effect. These results suggest that organic matter breakdown in arable soils is likely driven by other trophic levels (e.g., microorganisms or earthworms) with only a limited influence of the mesofauna community. We discuss these findings with regard to their implications for our current understanding of soil food web function and future European soil risk assessments. Integr Environ Assess Manag 2022;18:1423-1433. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
Topics: Animals; Arthropods; Biodiversity; Food Chain; Hexachlorocyclohexane; Insecticides; Oligochaeta; Soil
PubMed: 34878731
DOI: 10.1002/ieam.4563