Paraquat Concentration Research Articles

Adsorption and removal of herbicide paraquat from aqueous solutions via novel bimetal organic framework: Kinetics, equilibrium and statistical surface modeling

This study examines the adsorption and removal of the herbicide paraquat in relation to a bimetal organic framework known as the Terbium/Palladium Metal-Organic Framework (Tb/Pd-MOF). Analysis of N2 adsorption/desorption isotherms, which were used to assess the properties of the Tb/Pd-MOF, revealed that the absorption of paraquat on Tb/Pd-MOF resulted in a reduction in pore volume, pore size, and surface area. Specifically, the pore volume decreased from 8.25 to 5.68 cm3/g, the pore size decreased from 11.34 nm to 8.92 nm, and the surface area decreased from 1456.61 to 1262.82 m2/g. The pore radius also decreased from 0.96 nm to 0.58 nm. Tb/Pd-MOF’s functional groups were identified through FT-IR, and the structure of the compound was confirmed using XPS. Various adsorption parameters including temperature, adsorbent dosage, pH, paraquat concentration, and contact time were studied. Density functional theory (DFT) was used to understand the electrical properties, reactivity, and morphology of paraquat. Results from the DFT analysis revealed that the electrophilic and nucleophilic attack sites aligned with the molecular orbitals (HOMO and LUMO) and MEP outcomes. The study found that Tb/Pd-MOF demonstrated a significant absorption capacity for paraquat, with adsorption data consistent with the Langmuir isotherm and pseudo-second-order kinetic models. The paraquat adsorption capability of Tb/Pd-MOF was determined to be 574.8 mg/g. Furthermore, chemisorption was identified as the primary form of adsorption, as indicated by the adsorption energy of 26.98 kJ·mol−1. The optimal conditions for achieving a high adsorption capacity were identified as pH 8 and 0.02 g of Tb/Pd-MOF. The temperature-dependent changes in the thermodynamic parameters ΔG°, ΔH°, and ΔS° indicated that the paraquat absorption onto Tb/Pd-MOF occurred spontaneously, was endothermic, and involved random processes. To optimize the absorption process, Response Surface Methodology and Box-Behnken design (RSM, BBD) were employed. These techniques enabled effective removal of paraquat from the Tb/Pd-MOF material. During chemisorption, the adsorbate and adsorbent form chemical bonds, while aromatic rings are involved in π-π bonding. Additionally, pore-filling occurs when the adsorbate fills the pores of the adsorbent, and electrostatic interactions result from the attraction or repulsion of charges between the adsorbate and adsorbent. As a means of eliminating paraquat from wastewater, Tb/Pd-MOF demonstrates significant potential due to its diverse absorption processes and high capacity for adsorption.

Acquired resistance of Stenotrophomonas maltophilia to antimicrobials induced by herbicide paraquat dichloride.

Stenotrophomonas maltophilia, a ubiquitous environmental bacterium, is an important cause of nosocomial infections. Although banned in some countries, paraquat (PQ) is commonly used to control weeds. In this study, we investigated the effects of increasing concentrations of PQ on S. maltophilia and its antimicrobial resistance. The sequential exposure of S. maltophilia K279a to increasing concentrations of PQ induces the formation of strains with increased resistance to PQ. Among the 400 PQ-resistant isolates tested, 70 clones were resistant to 16 μg/ml ciprofloxacin (CIP), and around 18% of the PQ/CIP-resistant isolates showed increased resistance to all the tested antimicrobials including, the aminoglycosides, quinolones, cephalosporin, chloramphenicol, and co-trimoxazole. The results of the expression analysis of the antimicrobial resistance genes in the five selected PQ/CIP-resistant isolates demonstrated the high expression of genes encoding efflux pumps (smeYZ, smaAB, smaCDEF, smeDEF, smeVWX, and smtcrA) and the enzymes aph(3')-IIc, blaL1, and blaL2. However, expression of the genes known for PQ resistance (i.e., mfsA and sod) were not altered relative to the wild-type levels. Whole genome sequence analysis identified gene mutations that could account for the antimicrobial resistance, namely, smeT (TetR family regulatory protein), rplA (ribosomal protein L1), and acnA (aconitase A). Ectopic expression of wild-type AcnA partially complemented the fluoroquinolone-resistant phenotype of the mutant with mutated acnA, which suggests the role of aconitase A in antimicrobial susceptibility. Exposure of S. maltophilia to PQ thus induces the development of strains that increase resistance to multiple antimicrobials.

Low-Volume Electrochemical Sensor Platform for Direct Detection of Paraquat in Drinking Water

Direct testing of pesticide contaminants in drinking water is a challenge. Portable and sensitive sensor platforms are desirable to test water contaminants directly at farm and consumer levels. In this study, we have demonstrated the feasibility of an electrochemical sensor for the direct detection of paraquat (PQ) in drinking water samples. An immunoassay-based sensing platform was fabricated using PQ-specific antibody immobilized on the surface of the electrochemically reduced graphene oxide (rGO) modified screen-printed carbon electrode (rGO-SPCE). Using non-faradaic electrochemical impedance spectroscopy (EIS) as a detection tool, the sensor platform demonstrated a dynamic response for PQ concentration in drinking water ranging from 0.05 ng/mL to 72.9 ng/mL (0.19 to 243.8 nM), with a coefficient of determination (r2) of 0.997 and a limit of detection of 0.05 ng/mL (0.19 nM). Percentage recovery within ±20% error was obtained, and the sensor cross-reactivity test showed a selective response against glyphosate antigen. With the flexibility to use single-frequency EIS and low sample volume, the developed sensor demonstrated testing in water samples directly without any sample pre-processing. This low-volume electroanalytical sensor platforms can be translated into portable testing tools for the detection of various water contaminants.

A novel combination of wetland plants (Eichhornia crassipes) and biochar derived from palm kernel shells modified with melamine for the removal of paraquat from aqueous medium: a green and sustainable approach

Herbicide contamination in aquatic systems has become a global concern due to their long- term persistence, accumulation and health risks to humans. Paraquat, a widely used and cost-effective nonselective herbicide, is frequently applied in agricultural fields for pest control. Consequently, the removal of paraquat from contaminated water is crucial. This research presents a sustainable and environmentally benign method for paraquat removal from aqueous system by integrating wetland plants (Eichhornia crassipes) with biochar derived from melamine-modified palm kernel shells. The prepared biochar was characterized by using various analytical techniques. The effectiveness of biochar in enhancing phytoremediation was evaluated through a series of experiments, showing significant paraquat removal efficiencies of 99.7, 98.3, and 82.8% at different paraquat concentrations 50, 100, and 150 mg L−1, respectively. Additionally, present study examined the impact of biochar on the growth of E. crassipes, highlighting its potential to reduce the toxic effects of paraquat even present at higher concentrations. The paraquat removal mechanism was elucidated, focusing on the synergistic role of biochar adsorption and phytoremediation capability of E. crassipes. This innovative approach is an effective, feasible, sustainable and eco-friendly technique that can contribute to the development of advanced and affordable water remediation processes for widespread application.

Synaptotagmin-1 antagonizes paraquat intracellular accumulation and nephrocyte toxicity by up-regulating SERBP1/GLUT2 expression

Acute kidney injury (AKI) is common and an independent risk factor for mortality in patients with paraquat (PQ) poisoning. Currently, no specific antidote is available. Synaptotagmin-1 (SYT1) has been identified as a key protein that facilitates PQ efflux in PQ-resistant A549 cells, thereby preventing PQ-induced lung injury. However, the protective effect of STY1 on PQ-induced AKI remains to be elucidated. This study exposed human kidney 2 (HK-2) cells overexpressing SYT1 to PQ. These cells exhibited significantly lower levels of growth inhibition, reactive oxygen species production, early apoptosis, and PQ accumulation compared to the parent HK-2 cells. Transcriptomic screening and Western blot analysis revealed that SYT1 overexpression significantly promoted the expression of glucose transporter 2 (GLUT2). Inhibition of GLUT2 completely abolished the protective effects of SYT1 overexpression in HK-2 cells and restored intracellular PQ concentrations. Further immunoprecipitation-shotgun and RNA interference experiments revealed that SYT1 binds to and stabilizes the protein SERPINE1 mRNA-binding protein 1 (SERBP1), enhancing the stability of GLUT2 mRNA and its protein levels. In summary, SYT1 antagonizes PQ intracellular accumulation and prevents nephrocyte toxicity by up-regulating SERBP1/GLUT2 expression. This study identifies a potential target for the treatment of PQ-induced AKI.

Unveiling the ototoxic effects of paraquat on zebrafish larva

Paraquat is a widely utilized herbicide in agricultural fields posing a significant impact on human health and the environment due to its potent oxidant properties. Rampant paraquat usage leads to serious health hazards to farmers and the ecosystem, particularly the water bodies. Paraquat exposure can damage dopaminergic neurons causing Parkinson's disease in humans and other animal models. Extensive research has been done regarding the mode of action, pathophysiology and molecular mechanisms of paraquat-induced Parkinson's disease. Meanwhile, the ototoxic effect of paraquat remains poorly understood. Potential ototoxins can cause sensorineural hearing loss, one of the most common sensory disabilities in humans. In this study, we investigated the harmful effects of paraquat on neuromast hair cells in zebrafish larvae, a powerful model organism for auditory research. We treated sub-lethal concentrations (125 μM to 1000 μM) of paraquat to 3 and 4 dpf zebrafish larvae to investigate its ototoxic effects via rheotaxis behavioral assay, neuromast staining and scanning electron microscopy. The behavioral assay findings showed a drastic decline in the rheotaxis behavior in all the concentrations of paraquat-treated larvae. Furthermore, DASPEI neuromast vital staining displayed a dose-dependent reduction in the neuromast hair cells as we increased the paraquat concentration. The scanning electron microscope data revealed the significant shortening of kinociliary length, a decrease in stereociliary density and changes in semilunar peridermal cell morphology signifying the damaging effects of paraquat at the cellular level. Collectively, the behavioral, anatomical and morphological studies highlight the potential ototoxic effects of paraquat on zebrafish neuromast hair cells, further signifying its potential role in causing hearing loss in humans.

Portable Copper-Based Electrochemical SERS Sensor for Point-of-Care Testing of Paraquat and Diquat by On-Site Electrostatic Preconcentration.

With the advent of portable Raman spectrometers, the deployment of surface-enhanced Raman spectroscopy (SERS) in point-of-care testing (POCT) has been initiated. Within any analytical framework employing SERS, the acuity and selectivity inherent to the SERS substrate are of paramount importance. In this article, we utilize in situ electrochemical passivation technology to fabricate CuI passivation film, which serves as a flexible copper-based SERS substrate. Furthermore, portable electrochemical SERS (EC-SERS) sensors were prepared by combining this with laser direct writing technology. The detection signal was amplified using electrostatic preconcentration technology, showcasing impressive sensitivity, selectivity, and stability in pesticide detection. The detected concentrations of paraquat and diquat in tea reached as low as 3.36 and 2.43 μg/kg, respectively. Furthermore, the application of electrostatic preconcentration facilitated selective target molecule aggregation on the SERS sensor, markedly increasing Raman signal strength and enabling single-molecule detection. This research introduces an innovative POCT method for pesticides, promising to advance environmental monitoring's analytical capabilities.

Liver injury in paraquat poisoning: A retrospective cohort study.

Liver injury is one of the common complications of paraquat (PQ) poisoning, but whether the degree of liver injury is related to patient prognosis is still controversial. This study aimed to investigate whether liver injury was a risk factor for death in PQ-poisoned patients. We conducted a retrospective cohort study of PQ-poisoned patients from the past 10 years (2011-2020) from a large tertiary academic medical centre in China. PQ-poisoned patients were divided into a normal liver function group (n = 580) and a liver injury group (n = 60). Propensity score matching (PSM) analysis was then performed. A total of 640 patients with PQ poisoning were included in this study. To reduce the impact of bias, dose of PQ, urinary PQ concentration and time from poisoning to hospital admission were matched between the two groups. A 3:1 PSM analysis was performed, ultimately including 240 patients. Compared with the normal liver function group, patients in the liver injury group were older, had a higher R value ([ALT/ULN]/[ALP/ULN]) (p < .001) and had a higher mortality rate. Cox regression analysis showed that there was no significant association between alanine aminotransferase, alkaline phosphatase, total bilirubin levels and hazard of death, but age, PQ dose, creatine kinase isoenzyme, creatine kinase, white blood cell count, neutrophil percentage and lymphocyte percentage were associated with mortality in patients with PQ poisoning. The occurrence of liver injury within 48 h after PQ poisoning was a risk factor for mortality, and such liver injury was likely of a hepatocellular nature. Age, PQ dose, creatine kinase isoenzyme and white blood cell count were positively correlated with mortality, while creatine kinase, percentage of neutrophils and lymphocytes were inversely correlated.

Impact of polyvinyl chloride microplastic and paraquat herbicide on the blood cells, biochemical parameters, liver enzymes and morphological changes of aqueduct fish

In recent years, the surge in plastic production has led to pervasive pollution across all environments, earning us the title of inhabiting a “plastic world.” Consequently, this research endeavors to explore alterations in biochemical parameters, liver enzymes, and tissue integrity within the gills, intestines, and liver of black fish subjected to polyvinyl chloride (PVC) microplastics and paraquat herbicide, both individually and in combination. For this purpose, we allocated 90 blackfish specimens into 9 groups consisting of 10 individuals each through random selection. Following a period of 28 days, we carried out an assessment to investigate the toxic effects of PVC and paraquat, both separately and in combination. Subsequently, The results indicate that the number of red blood cells (RBCs, millions/mm3) in all studied groups (Group G: 3.6 ± 0.18; Group H: 3.5 ± 0.17; and Group I: 3.2 ± 0.16) is significanly lower than the control group (Pvalue<0.05). The glucose levels in all studied groups (Group B: 47 ± 5.12; Group C: 48 ± 3.79; Group D: 51 ± 4.14; Group E: 48 ± 5.37; Group F: 53 ± 7.48; Group G: 53 ± 9.24; Group H: 58 ± 10.43; and Group I: 61 ± 8.71) are higher than the control group (46 ± 3.71). The results indicate that the levels of AST enzyme in all studied groups (group B: 30 ± 0.17; group C: 32 ± 1.61; group D: 34 ± 1.92; group E: 33 ± 1.17; group F: 38 ± 2.27; group G: 38 ± 1.71; group H: 43 ± 2.15; and group I: 46 ± 2.33). Groups F, G, H, and I exhibit significantly higher levels of AST enzyme compared to the control group, with a p-value<0.05. Morphological changes observed in erythrocytes include deformation and cell vacuolation. The maximum amount of changes in the morphology of erythrocytes occurs when black fish is exposed to 2 mg/L of PVC and 0.4 mg/L of paraquat (group I). The histological harm caused by the combination of PVC and paraquat is significant. Findings indicate that increasing the concentration of both microplastics and paraquat enhances their toxicity when combined. Consequently, it's imperative to assess the toxic impact of microplastics (MPs) and paraquat individually, as well as in combination, on aquatic organisms to safeguard them from the detrimental effects of these substances.

Selective detection of paraquat by a cucurbit[7]uril-based fluorescent probe.

A simple fluorescent "on-off" system that can be utilized for the selective identification and determination of paraquat (PQ) is presented herein. 1H NMR spectroscopic data indicated that in aqueous solution the alkaloid palmatine can be partially encapsulated within the cucurbit[7]uril (Q[7]) cavity, whereby a stable 1 : 1 host-guest inclusion complex is formed. Other characterization techniques including mass spectrometry, UV-Vis and fluorescence spectroscopy also provided further evidence, and the host-guest inclusion complex was found to exhibit reasonable fluorescence intensity. It is noteworthy that the addition of PQ resulted in quenching the fluorescence of the host-guest inclusion complex, whereas the presence of 12 other pesticides did not significantly affect the fluorescence intensity. Given the linear relationship between the intensity of the fluorescence and the PQ concentration, the PQ concentration in aqueous solution was easily detected. Thus, a new method for identifying and determining the fluorescence quenching of PQ has been developed in this work.

Influence of Pesticides Contamination on Microbial Population of Selected Farmlands

Pesticides play a pivotal role in agriculture by combating various pests and increasing crop yields. However, extensive use of pesticides can result in unintended consequences, including potential impact on soil microbes. This study was aimed at investigating the influence of pesticides contamination on microbial population of farmlands in Otuoke, Nigeria. Soil samples were collected from four pesticide treated farmlands designated Bakery 1, Bakery 2, Dorcas, and PGS. A farmland without pesticide treatment served as Control. Microbial population, physiochemical parameters and pesticide residue of samples were investigated using standard techniques. Results revealed significant differences in microbial populations between pesticide-contaminated soils and control. The highest bacterium isolated and occurrence (%) in each location was; Streptomyces coelicolor 42(45.7%), Proteus vulgaris 179(59.9%), Streptomyces scabies 41(38.7%), Streptococcus pyrogenes 101(44.7%), and Pseudomonas aeruginosa 69(40.6%) for Bakery 1, Bakery 2, Dorcas, PGS, and control respectively. Highest fungus isolated and occurrence (%) was; Rhodotorula glutini 51(82.3%), 31(77.5%), and 43(81.1%) for Bakery 1, Bakery 2, and Dorcas respectively; and Candida tropicalis 25(80.6%) and Lichtheimia hyalospora 4(28.6%) for PGS and Control respectively. Pesticide analysis showed that Paraquat dichloride, Endosulfan, Diazinon, and N-(phosphonomethyl) glycine were present in the soil samples with about 75% residue. Site-specific pesticide concentrations varied in soil samples, with Bakery 1 having the highest concentrations Endosulfan and Diazinon, bakery 2 had highest concentration of N-(phosphonomethyl) glycine, and PGS had the highest concentration of Paraquat. Physiochemical characteristics showed that temperature ranged from 28.70 – 26.70°C, electrical conductivity 508 – 365µS/cm, moisture content 7.50 - 3.10%, pH 6.90 -3.90, and organic matter 4.70 – 3.00%. Decreasing order of cation exchange capacity (CEC) in farmlands was PGS &gt; Bakery 2 &gt; Bakery 1 &gt; Dorcas &gt; Control. There was no significant difference (p &gt; 0.05) in each parameter between locations

A new strategy for constructing 3D hybrid graphene/Au/rectangular pyramids PMMA on a flexible SERS substrate for trace molecule detection

Surface enhanced Raman spectroscopy (SERS) has attracted interest in the fields of hazardous substance detection and food safety. However, its limited sensitivity and SERS signal consistency inhibit the widespread use of SERS technology. Herein, a novel approach for the fabrication of a graphene/Au NP/rectangular pyramid PMMA hybrid SERS substrate (Gr/Au/RP PMMA) with high uniformity and sensitivity is presented. The Gr/Au/RP PMMA substrate is machined by indentation firstly, then following wet etching of the copper substrate. The Raman enhancement of Gr/Au/RP PMMA is studied in terms of both electromagnetic enhancement and chemical enhancement. The field strength enhancement of the obtained Gr/Au/RP PMMA substrate is more than 4.9 times greater than that of the Gr/Au/flat PMMA substrate, established using a COMSOL simulation. By actively modulating the machining parameters on a Cu-Gr surface, the number of Gr layers, as well as the Gr/Au/RP PMMA topography, can be controlled, which can effectively influence the performance of the SERS substrate. Moreover, compared with other SERS substrates, including Gr/Au/RP PMMA, Gr/Au/flat PMMA, Au/Gr/RP Cu, Gr/RP PMMA, and Au/RP PMMA, the Raman intensities of R6G were strongest on the Gr/Au/RP PMMA. In addition, the minimum detectable concentrations of paraquat (PQ) and 2,4-d used in situ detection were 10−8 M and 10−6 M, respectively, after being covered with the Gr/Au/RP PMMA flexible substrate. To test its practical applicability with actual fruit surfaces, the Gr/Au/RP PMMA flexible substrate was used for the in situ SERS detection of PQ on apples. Clear Raman peaks of 10−7 M PQ were detected on the apple surface.

Modified calix[4]arene with pyrene sulfonyl linkage: Fluorescence and electrochemical sensor for the detection of paraquat in potatoes via host–guest chemistry

In this presented work, we propose a new calix[4]arene-pyrene based supramolecular fluorescence system C4Py, constructed for the recognition of paraquat (PQ) herbicide. The proposed method shows fluorescence “turn-off” effect while binding of PQ with C4Py, by quenching the fluorescence intensity of C4Py. Excellent selectivity for PQ is demonstrated by a comparison with other various types of pesticides. The limit of detection is found to be 7.14 µM by fluorescence experiment. The recognition event has been confirmed by 1H NMR as well as MALDI-TOF analysis. This approach was validated by PQ with spiking experiments using potatoes as real sample, exhibiting 7.692 ppm limit of detection. For the further confirmation of C4Py: PQ binding, the electrochemical study was also carried out using cyclic voltammetry and differential pulse voltammetry. The results of electrochemical study demonstrated a decrease of the oxidation peak current on increasing concentration of PQ into C4Py solution confirming binding of PQ with C4Py.

RSPSSL: A novel high-fidelity Raman spectral preprocessing scheme to enhance biomedical applications and chemical resolution visualization

Raman spectroscopy has tremendous potential for material analysis with its molecular fingerprinting capability in many branches of science and technology. It is also an emerging omics technique for metabolic profiling to shape precision medicine. However, precisely attributing vibration peaks coupled with specific environmental, instrumental, and specimen noise is problematic. Intelligent Raman spectral preprocessing to remove statistical bias noise and sample-related errors should provide a powerful tool for valuable information extraction. Here, we propose a novel Raman spectral preprocessing scheme based on self-supervised learning (RSPSSL) with high capacity and spectral fidelity. It can preprocess arbitrary Raman spectra without further training at a speed of ~1 900 spectra per second without human interference. The experimental data preprocessing trial demonstrated its excellent capacity and signal fidelity with an 88% reduction in root mean square error and a 60% reduction in infinite norm (L∞\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${L}_{{\\infty }}$$\\end{document}) compared to established techniques. With this advantage, it remarkably enhanced various biomedical applications with a 400% accuracy elevation (ΔAUC) in cancer diagnosis, an average 38% (few-shot) and 242% accuracy improvement in paraquat concentration prediction, and unsealed the chemical resolution of biomedical hyperspectral images, especially in the spectral fingerprint region. It precisely preprocessed various Raman spectra from different spectroscopy devices, laboratories, and diverse applications. This scheme will enable biomedical mechanism screening with the label-free volumetric molecular imaging tool on organism and disease metabolomics profiling with a scenario of high throughput, cross-device, various analyte complexity, and diverse applications.

Barnyardgrass (Echinochloa crus-galli) control and rice injury with labeled herbicides following exposure to sub-lethal concentrations of paraquat

Abstract Rice in Mississippi is often in early seedling growth stages when paraquat-based herbicide treatments are commonly applied to corn, cotton, and soybean; therefore, off-target movement onto adjacent rice fields may occur. After an off-target movement event has occurred, weed management in the rice crop is still necessary. Field studies were conducted from 2019 to 2021 in Stoneville, MS, to evaluate rice injury and barnyardgrass control with labeled herbicides after exposure to a sub-lethal paraquat concentration. Labeled herbicide treatments were recommended rates of imazethapyr, quinclorac, propanil, bispyribac-sodium, cyhalopfop, and florpyrauxifen-benzyl applied following rice exposure to a sub-lethal concentration of paraquat. Rice injury was detected 7 and 28 d after treatment (DAT) with injury ≥ 35 and 14%, respectively, following all labeled herbicides. Florpyrauxifen-benzyl and imazethapyr injured rice the greatest 28 DAT. Following paraquat exposure, barnyardgrass control was similar for all labeled herbicide treatments 7, 14, and 28 DAT except with florpyrauxifen-benzyl and no labeled herbicide (paraquat alone) 7 DAT. Across all evaluations, barnyardgrass control was at least 12% greater following paraquat exposure and labeled herbicide treatments than with no paraquat exposure. The current research demonstrates that labeled herbicides applied following exposure to a sub-lethal concentration of paraquat resulted in &lt;36% injury and provided as great as 95% control of barnyardgrass, depending on the herbicide treatment. Therefore, the labeled herbicides choice following rice exposure to a sub-lethal concentration of paraquat should be based on weed spectrum.

Utilizing symmetrical tetramethyl cucurbit[6]uril-based supramolecular fluorescence probe for detection of paraquat in water

A supramolecular fluorescence probe has been developed using a symmetrical tetramethyl cucurbit[6]uril (TMeQ[6]) and a styryl derivative (SPy) with a host–guest ratio of 2:1. The introduction of paraquat (PQ) competes with SPy for the TMeQ[6] cavity, resulting in fluorescent quenching. The addition of 17 common herbicides and ions had negligible effects on the fluorescence quenching, indicating that the 2TMeQ[6]/SPy complex exhibits excellent selectivity in detecting PQ. The detection limit was found to be 4.62 × 10-7 M. More importantly, the probe was engineered to detect paraquat in river water by examining post-treatment samples and noting alterations in fluorescence color. The red to blue (R/B) intensity ratio is subsequently calculated to ascertain the PQ concentration. Experimental trials conducted on river water samples yielded recovery rates between 98.21 % and 108 %, with a relative standard deviation of less than 5 %. By pairing this with a smartphone-based colorimetric analysis application, we can facilitate portable PQ detection, enabling efficient and convenient monitoring across various locations.

LIVING LONGER WITH MODERATE AMOUNTS OF OXYGEN RADICALS IN FRUIT FLIES

Abstract The role of reactive oxygen species (ROS) in aging is complex and paradoxical. While the free radical theory of aging suggests that ROS cause cellular damage and senescence, some studies have shown that moderate ROS levels can enhance cellular adaptation and longevity. In this research, we used Drosophila as an in vivo model to investigate the optimal level of ROS that can promote healthy aging. We exposed flies to different concentrations of paraquat (PQ), a herbicide that generates superoxide anions, and measured their lifespan, stress resistance, and gene expression. We found that intermediate PQ levels (0.1 mM) extended lifespan and improved stress tolerance, while high PQ levels (0.5 mM) shortened lifespan and impaired stress response. We also observed an up-regulation of ROS scavenger genes, such as superoxide dismutase 1 and glutathione peroxidase, in the intermediate PQ group, suggesting a homeostatic mechanism to balance ROS levels. Our findings challenge the conventional view of ROS as harmful agents and provide novel insights into the molecular mechanisms of aging.

The interaction between Fe and Co dual active sites for promoting ultra-sensitive detection of trace paraquat

Paraquat is a highly toxic herbicide, and its residue in food poses a huge threat to human health. High-sensitivity detection of trace paraquat is crucial but challenging. Herein, we theoretically predicted that FeCo-MOF materials with Fe and Co dual active sites have potential interactions with paraquat. Moreover, a porous FeCo-MOF materials with Fe and Co dual active sites were in-suit constructed on the surface of foam nickel by self-assembly strategy, and used for the electrochemical detection of paraquat. The electrochemical detection results indicate that the prepared FeCo-MOF foam nickel electrode exhibited ultra-high detection sensitivity (113.85 μA nM−1 cm−2) and trace detection limit (0.16 nM) in a wide range of paraquat concentration (1.00 nM–5.00 mM). In addition, we successfully used this FeCo-MOF foam nickel electrode for the detection of paraquat in apples, human serum, and fresh tea leaves (detection recovery is 97.00 %–99.99 %). Furthermore, the density functional theory (DFT) and X-ray photoelectron spectroscopy (XPS) confirm that Fe and Co are active sites for detecting paraquat, and the interaction between Fe and Co promotes highly sensitive detection of trace paraquat. Therefore, this work provides strategies and comprehension for designing and modulating active sites at the microscopic level to improve sensitivity for detecting toxic pesticides.

3D nanocake-like Au-MXene/Au pallet structure-based label-free electrochemical aptasensor for paraquat determination.

3D nanocake-like Au-MXene and Au pallet (Au-MXene/AuP) nanocomposite-modified screen-printed carbon electrodes (SPCEs) were utilized to construct an ultrasensitive label-free electrochemical aptasensor through a self-assembly procedure for trace paraquat (PQ) residue detection. Benefiting from the excellent electrochemical (EC) performances (e.g., high conductivity and large surface area) of Au-MXene nanocomposites and AuP substrate, the developed Apt/Au-MXene/AuP/SPCE-based EC aptasensor displayed excellent specificity and anti-interference ability, good repeatability, and stability. A linear relationship between the log value of the change in current intensity [lg (ΔI)] and the log value of the concentration of PQ [lg (CPQ)] was obtained in the range 0.05-1000 ng/mL. The limit of detection was 0.028 ng/mL, and thesensitivity was 255.5 μA/(μM·cm2). Practical applications in malt and mint samples confirmed the accuracy of the EC aptasensor in complex matrices for PQ detection, providing a universal analytical tool for othertrace pesticides in differentfood samples by simply replacing the corresponding aptamers.

Plant extracts as an eco-friendly approach to remove paraquat from aqueous solution

Nowadays, water pollution by herbicides is known as a global concern. Paraquat (PQ) (1-1-methyl-4,4-bi-pyridinium-dichloride) is a chip with high performance, which is being widely used herbicide to remove weeds from agricultural and natural ecosystems. PQ can contaminate water sources due to its high solubility in water. Human death by poisoning effects of PQ has been reported in several countries. Therefore, the side effects of PQ are a global challenge. This study aimed to investigate the bioremediation of PQ by plant extracts, as a low-cost, nontoxic, and natural absorbent to remove PQ from aqueous solutions in different conditions. In this regard, the extracts of common purslane (portulaca oleracea), florist kalanchoe (kalanchoe blossfeldiana), and jade plant (crassula portulaca) were used as adsorbents. For this purpose, the effect of various parameters such as contact time, initial concentration of PQ solution, temperature, pH, and amount of extract was investigated. The results of present study showed that P. oleracea extract and C. portulaca extracts have higher adsorption efficiency than k. blossfeldiana extract. The highest PQ removal was obtained by P. oleracea extract (79.04%) and C. portulaca extract (78.72%) at pH = 11, the adsorbent content of 0.2 mg L−1, and the lowest absorption of PQ (50.6%) was obtained by K. blossfeldiana extract. The highest PQ removal by plant extract was observed at 30 min for P. oleracea and C. portulaca, and at 15 min for k. blossfeldiana extract. Moreover, surface absorption capacity increased with increasing plant extract concentration, decreasing PQ concentration and decreased with increasing temperature. Finally, it can be concluded that plant extract can help to remove PQ from the aqueous solution.