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In the ratiometric fluorescent (RF) strategy, the selection of fluorophores and their respective ratios helps to create visual quantitative detection of target analytes. This study presents a framework for optimizing ratiometric probes, employing both two-component and three-component RF designs. For this purpose, in a two-component ratiometric nanoprobe designed for detecting methyl parathion (MP), an organophosphate pesticide, yellow-emissive thioglycolic acid-capped CdTe quantum dots (Y-QDs) (analyte-responsive), and blue-emissive carbon dots (CDs) (internal reference) were utilized. Mathematical polynomial equations modeled the emission profiles of CDs and Y-QDs in the absence of MP, as well as the emission colors of Y-QDs in the presence of MP separately. In other two-/three-component examples, the detection of dopamine hydrochloride (DA) was investigated using an RF design based on blue-emissive carbon dots (B-CDs) (internal reference) and N-acetyl L-cysteine functionalized CdTe quantum dots with red/green emission colors (R-QDs/G-QDs) (analyte-responsive). The colors of binary/ternary mixtures in the absence and presence of MP/DA were predicted using fitted equations and additive color theory. Finally, the Euclidean distance method in the normalized CIE XYZ color space calculated the distance between predicted colors, with the maximum distance defining the real-optimal concentration of fluorophores. This strategy offers a more efficient and precise method for determining optimal probe concentrations compared to a trial-and-error approach. The model's effectiveness was confirmed through experimental validation, affirming its efficacy. [ABSTRACT FROM AUTHOR]

Reformatsky reagent obtained from methyl 1-bromocyclopentanecarboxylate and zinc selectively added to the carbon–carbon double bond of the heterocyclic fragment of 3-(3-arylacryloyl)-2H-chromen-2-ones to give the corresponding addition products after hydrolysis of the reaction mixture. According to the X-ray diffraction data, the products exist in the enol form. Despite the use of excess Reformatsky reagent, elevated temperature, and prolonged reaction time, neither addition to the acryloyl fragment nor intramolecular cycliza-tion of the addition products was observed. [ABSTRACT FROM AUTHOR]

Organophosphorous (OP) pesticides can cause many human diseases. In this study, the separation and determination of two organophosphorous pesticides (diazinon and methyl-parathion) in biological samples using solid-phase extraction method prior to their measurements by high‐performance liquid chromatography (HPLC) were investigated. Herein, a new functionalized cerium-based metal–organic framework (MOF) bearing oxime moiety, denoted here UiO-66(Ce)-MO, was synthesized through two-synthetic steps from the pristine UiO-66(Ce) and then applied as an efficient porous adsorbent for the extraction of pesticides from biological samples. Various techniques including Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Brunauer–Emmett–Teller (BET) analysis were used for the description of adsorbent. The optimization of variables was performed by Box–Behnken design combined with response surface methodology. The factors' effects including pH, eluent volume (EV), sample flow rate (SF) and eluent flow rate (EF) were also examined. The optimum conditions for both compounds were pH 5.5, eluent volume 0.6 mL, SF 2 mL min−1, and EF 0.2 mL min−1, leading to 97.1% and 96.0% removal of diazinon and methyl-parathion, respectively. Under the optimum conditions, the maximum adsorption capacity was obtained 454.5 mg g−1 for methyl-parathion and 476.2 mg g−1 for diazinon. The limit of detection (LOD) was found to be 0.04 μgL−1 for diazinon and 0.06 μgL−1 for methyl-parathion. Sensitivity analysis showed that pH plays a significant role on the efficiency of both organic pollutants. Remarkably, the results showed that this adsorbent outperforms the other UiO-66(Ce) samples and is suitable for separation and determination of these organic materials from water and biological real samples (blood plasma and urine). A porous oxime-functionalized Ce-MOF, UiO-66(Ce)-MO, was synthesized and applied for efficient extraction and determination of trace amounts of methyl-parathion and diazinon from water and biological samples. [ABSTRACT FROM AUTHOR]

In this contribution, we describe the kinetics associated with the rac-Me2Si[2-Me-4-Ph-Ind]2ZrCl2 (Cat-1)/borate/TIBA catalyzed copolymerization of E/dienes (isoprene (IP), butadiene (BD), 5-ethylidene-2-norbornene (ENB), 4-vinylcyclohexene (VCH) and vinyl norbornene (VNB)), and E/diene/1-hexene (1H) terpolymerization by using thiophenecarbonyl chloride (TPCC) that was used in Ziegler-Natta (Z-N) and metallocene-catalyzed polyethylene (PE) and polypropylene (PP) and E/P polymerizations. In both types of polymerizations, a higher amount of dienes was incorporated when VNB (2.70 mole %) and VCH (1.56 mole %) were added as comonomer, but IP and BD were incorporated with the moderated rate (0.6-1.1 mole %) with higher activities (3.45x106gm/mmolMt·h). The active center [Zr]/[C*] fraction is higher (61%) than previously reported PE polymerizations, especially in the case of E/IP, E/BD and E/IP/1H but lower than E/P (87%) copolymerization. Significantly, IP and BD activated the inactive catalytic sites that were dormant in the PE. The propagation rate constant (kpE) with IP was higher (kp564 Lmol-1s-1), while kpE with VNB (kp379 Lmol-1s-1) and VCH (kp304 Lmol-1s-1), which were lower than PE. This difference is built because of the diffusion barrier in the system. Compared to E/diene copolymers, kpE values in E/diene/1H terpolymerizations for IP, VCH, and VNB are higher and stable except ENB and determine that 1H prevents the insertion of dienes and reduces the crystalline properties resultant moderate kpE. Even though the E/BD copolymers decreased butadiene content of over 2 mol% resulted in better crystalline characteristics, lower diffusion barriers, and a higher kpE value. In concept, IP and BD are linear and readily available for coordination. While VCH, ENB and VNB are cyclic and bulky, metallocene in contact ion pairs cannot accept ENB, VNB, and VCH for coordination and subsequently act as dormant in the polymerization. [ABSTRACT FROM AUTHOR]

Metal–organic framework (UiO-66) derived nanoporous carbon/electrochemically reduced graphene oxide nanocomposite (UiO-66/NPC/ERGO) was developed to fabricate an electrochemical sensor for achieving efficient detection of methyl parathion (MP) residues in food. The carbonization derivative UiO-66/NPC was synthesized by one-step pyrolysis with only UiO-66 precursor. Based on the synergistic effect of enough active absorption sites and specific absorption of UiO-66/NPC for MP as well as the high conductivity of ERGO, the UiO-66/NPC/ERGO sensor exhibited excellent sensing performance. Under the optimal conditions, a linear determination range of 20–4000 ng/mL and low limit of detection (LOD) of 0.395 ng/mL for MP was obtained by direct electrochemical oxidation using SWV. Additionally, the sensor provided excellent stability and selectivity, as well as effective determination of real samples with satisfactory recoveries (98.5–104.0%), manifesting that the UiO-66/NPC/ERGO has great potential for organophosphorus pesticide detection. [ABSTRACT FROM AUTHOR]

Electrochemical impedance spectroscopy (EIS) is a highly effective technique for studying the surface of electrodes in great detail. EIS-based electrochemical sensors have been widely reported, which measure the charge transfer resistance (Rct) of redox probes on electrode surfaces to monitor the binding of target molecules. One of the protective drugs against hemorrhagic cystitis caused by oxazaphosphorine chemotherapy drugs such as ifosfamide, cyclophosphamide and trophosphamide is Mesna (sodium salt of 2-mercaptoethanesulfonate). The increase in the use of Mesna due to the high consumption of anti-cancer drugs, the determination of this drug in biological samples is of particular importance. So far, no electrochemical method has been reported to measure Mesna. In this research, a novel impedimetric sensor based on a glassy carbon electrode (GCE) modified with oxidized multiwalled carbon nanotubes (MWCNTs)/gold nanoparticle (AuNPs) (denoted as Au NPs/MWCNTs/GCE) for impedimetric determination of Mesna anticancer drug was developed. The modified electrode materials were characterized by field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), and EIS. The electrochemical behavior of Mesna at the surface of Au NPs/MWCNTs/GCE was studied by an impedimetric method. The detection mechanism of Mesna using the proposed impedimetric sensor relied on the increase in the Rct value of [Fe (CN)6]3−/4− as an electrochemical probe in the presence of Mesna compared to the absence of Mesna as the analyte. Under the optimum condition, which covered two linear dynamic ranges from 0.06 nmol L−1 to 1.0 nmol L−1 and 1.0 nmol L−1 to 130.0 µmol L−1, respectively. The detection limit was 0.02 nmol L−1. Finally, the performance of the proposed sensor was investigated for Mesna electrochemical detection in biological samples. [ABSTRACT FROM AUTHOR]

Pesticide pollution in recent times has emerged as a grave environmental problem contaminating both aquatic and terrestrial ecosystems owing to their widespread use. Bioremediation using gene editing and system biology could be developed as an eco-friendly and proficient tool to remediate pesticide-contaminated sites due to its advantages and greater public acceptance over the physical and chemical methods. However, it is indispensable to understand the different aspects associated with microbial metabolism and their physiology for efficient pesticide remediation. Therefore, this review paper analyses the different gene editing tools and multi-omics methods in microbes to produce relevant evidence regarding genes, proteins and metabolites associated with pesticide remediation and the approaches to contend against pesticide-induced stress. We systematically discussed and analyzed the recent reports (2015–2022) on multi-omics methods for pesticide degradation to elucidate the mechanisms and the recent advances associated with the behaviour of microbes under diverse environmental conditions. This study envisages that CRISPR-Cas, ZFN and TALEN as gene editing tools utilizing Pseudomonas, Escherichia coli and Achromobacter sp. can be employed for remediation of chlorpyrifos, parathion-methyl, carbaryl, triphenyltin and triazophos by creating gRNA for expressing specific genes for the bioremediation. Similarly, systems biology accompanying multi-omics tactics revealed that microbial strains from Paenibacillus, Pseudomonas putida, Burkholderia cenocepacia, Rhodococcus sp. and Pencillium oxalicum are capable of degrading deltamethrin, p-nitrophenol, chlorimuron-ethyl and nicosulfuron. This review lends notable insights into the research gaps and provides potential solutions for pesticide remediation by using different microbe-assisted technologies. The inferences drawn from the current study will help researchers, ecologists, and decision-makers gain comprehensive knowledge of value and application of systems biology and gene editing in bioremediation assessments. [ABSTRACT FROM AUTHOR]

The current approach for the risk assessment of chemicals does not account for the complex human real-life exposure scenarios. Exposure to chemical mixtures in everyday life has raised scientific, regulatory, and societal concerns in recent years. Several studies aiming to identify the safety limits of chemical mixtures determined hazardous levels lower than those of separate chemicals. Following these observations, this study built on the standards set by the real-life risk simulation (RLRS) scenario and investigated the effect of long-term exposure (18 months) to a mixture of 13 chemicals (methomyl, triadimefon, dimethoate, glyphosate, carbaryl, methyl parathion, aspartame, sodium benzoate, EDTA, ethylparaben, butylparaben, bisphenol A and acacia gum) in adult rats. Animals were divided into four dosing groups [0xNOAEL (control), 0.0025xNOAEL (low dose—LD), 0.01xNOAEL (medium dose—MD) and 0.05xNOAEL (high dose-HD) (mg/kg BW/day)]. After 18 months of exposure, all animals were sacrificed, and their organs were harvested, weighed, and pathologically examined. While organ weight tended to be higher in males than in females, when sex and dose were taken into account, lungs and hearts from female rats had significantly greater weight than that of males. This discrepancy was more obvious in the LD group. Histopathology showed that long-term exposure to the chemical mixture selected for this study caused dose-dependent changes in all examined organs. The main organs that contribute to chemical biotransformation and clearance (liver, kidneys, and lungs) consistently presented histopathological changes following exposure to the chemical mixture. In conclusion, exposure to very low doses (below the NOAEL) of the tested mixture for 18 months induced histopathological lesions and cytotoxic effects in a dose and tissue-dependent manner. [ABSTRACT FROM AUTHOR]

Developing simple, efficient, and inexpensive method for trace amount organophosphorus pesticides' (OPs) detection with high sensitivity and specificity is of significant importance for guaranteeing food safety. Herein, an Ag/Au bimetallic nanoparticle-based acetylcholinesterase (AChE) surface-enhanced Raman scattering (SERS) biosensor was constructed for in situ simple and sensitive detection of pesticide residues in food. The principle of this biosensor exploited 4-mercaptophenylboronic acid (4-MPBA)-modified Ag/Au bimetallic nanoprobes as SERS signal probe to improve sensitivity and stability. The combination of AChE and choline oxidase (CHO) can hydrolyze acetylcholine (ATCh) to generate H2O2. The product of H2O2 selectively oxidizes the boronate ester of 4-MPBA, decreasing the Raman intensity of the B-O symmetric stretching. In the presence of OPs, it could inhibit the production of H2O2 by destroying the AChE activity, so the reduction of the SERS signal was also alleviated. Based on the principle, an Ag/Au bimetallic nanoparticle-based AChE SERS sensor was established without any complicated pretreatments. Benefiting from the synergistic effects of Ag/Au bimetallic hybrids, a linear detection range from 5×10−9 to 5×10−4 M was achieved with a limit of detection down to 1.7×10−9 M using parathion-methyl (PM) as the representative model of OPs. Moreover, the SERS biosensor uses readily available reagents and is simple to implement. Importantly, the proposed SERS biosensor was used to quantitatively analyze OP residues in apple peels. The levels of OPs detected in real samples by this method were consistent with those obtained using gas chromatography–mass spectrometry (GC–MS), suggesting the proposed assay has great potential applications for OPs in situ detection in food safety fields. [ABSTRACT FROM AUTHOR]

Synthetic β-cyclodextrin/zeolite-A (CD/ZA) composite was evaluated as a potential adsorbent for Cd2+, PO43−, and methyl parathion (MP). The CD/ZA particles exhibit higher Cd2+ (223 mg/g), PO43− (196.2 mg/g), and MP (368.7 mg/g) Qsat values than zeolite-A reflecting the impact of the integrated polymer. The Cd2+, PO43−, and MP uptake follows the classic assumptions of Pseudo-First order kinetics and Langmuir isotherm. The monolayer equilibrium model of one energy site was applied for more details about the adsorption systems. Based on the model findings, the CD/ZA particles can adsorb up to 4 Cd2+ ions (n = 2.76 to 3.03), 3 PO43− ions (n = 2.2 to 2.31), and 2 MP molecules (n = 1.89 to 1.94) per site. The adsorption site densities of Cd2+ (75.9 mg/g), PO43− (87.9 mg/g), and MP (194.7 mg/g) illustrate the high uptake properties of MP. Based on the classic kinetics, equilibrium, and Gaussian energies (˂ 8 kJ/mol) findings, the pollutants were adsorbed by physical processes in monolayer and homogenous forms. This was supported by the adsorption energies (˂ 40 kJ/mol) that reflected the effect of van der Waals, hydrogen bonding, and dipole bonding forces. The thermodynamic functions validate the spontaneous and exothermic behaviors of the adsorption systems. The composite display significant recyclability and affinity for the studied contaminants under the competitive effect of other ions (Pb2+, Zn2+, NO3−, SO42−, malachite green, and chlorpyrifos). [ABSTRACT FROM AUTHOR]

A highly sensitive electrochemical sensor using a calix[6]arene/bismuth ferrite/multiwall carbon nanotube-modified fluorine-doped tin oxide electrode (CA6/BFO/MWCNTs/FTO) was fabricated for the detection of methyl parathion. The MWCNTs, BFO, and CA6 were consecutively cast onto the FTO electrode surface to enhance the surface area, electron transfer, and selectivity of sensors. The electrochemical behavior of CA6/BFO/MWCNTs/FTO was studied via cyclic voltammetry and electrochemical impedance spectroscopy. MP was detected via cyclic voltammetry in a phosphate buffer solution at pH 7.0. The working principle of the sensor involves a linear decrease in the anodic peak current of BFO with increasing MP concentration. The linear working ranges are 0.005–0.05 nM and 0.07–1.5 nM. The CA6/BFO/MWCNTs/FTO sensor provides a low detection limit (S/N = 3) of 5 pM and a high electrochemical sensitivity of 1.23 A μM–1 cm–2. The fabricated sensor was successfully applied to assess the presence and amount of MP in vegetables and fruits (recoveries of 82.0–106.8%), with results comparable to high-performance liquid chromatography. [ABSTRACT FROM AUTHOR]

In conclusion, this study has successfully developed a novel SERS substrate using Fe3O4@UiO-66(Zr)@Ag nanoparticles for the detection of OPs in food samples. In this work, a new SERS substrate, Fe3O4@UiO-66(Zr)@Ag nanoparticles (FUAs), was developed and applied for trace detection of organophosphorus pesticides (OPs) in food. Surface-enhanced Raman spectroscopy (SERS) has attracted much attention as a rapid, sensitive, and non-destructive method for trace analysis, especially in food and biological samples (Yun et al., 2012). [Extracted from the article]

A dual-emission fluorescent (FL) probe was constructed by coordinating Cu2+ of copper metal–organic frameworks (Cu-MOFs) with − COO− group of carbon dots (CDs) for pesticide thiophanate-methyl (TM) determination. TM was recognized by organic ligands (H2BDC and H2BDC-NH2) of Cu-MOFs via π stacking. Due to the higher affinity of Cu2+ to TM than ligands and CDs, TM chelated with Cu2+ to form TM-Cu complex. Thus coordination of Cu-MOFs was damaged and the ligands were released resulting in the FL intensity increase of Cu-MOFs (F430). And also CDs were released from CDs@Cu-MOFs hybrids and electron transfer from CDs to CuMOFs was inhibited, leading to the FL intensity increase of CDs (F600). The FL intensity ratio (F430/F600) showed a good linear relationship with TM concentrations of 0.0307–0.769 μmol L−1 with a limit of detection (LOD) of ~ 3.67 nmol L−1. The probe was successfully applied to detect TM in spiked food samples with satisfactory recoveries of 93.1–113%. Additionally, visual detection of TM was achieved according to the fluorescence color variation from blue to carmine, indicating promising application of CDs@Cu-MOFs probe. [ABSTRACT FROM AUTHOR]

Two green nanocomposites of Co3O4 decorated CTAB/bentonite (Co@CT/BE) and chitosan/bentonite (Co@CH/BE) were synthesized as enhanced and environmental photocatalysts and antibacterial agents. As photocatalysts, the products were applied in the effective oxidation of toxic methyl parathion pesticide (MP) in wastewater under a visible light source. The application of Co@CH/BE (0.02 g) resulted in the complete oxidation of MP (50 mg/L) after 40 min and complete mineralization after 60 min. while the complete oxidation and mineralization of MP (50 mg/L) by Co@CT/BE was recognized after 75 min and 100 min, respectively. The Co@CH/BE composite is of higher activity than Co@CT/BE and can cause complete oxidation for MP at high concentrations up to 100 mg/L after 75 min. The oxidation pathway was illustrated considering the existence of the hydroxyl radicals as the active oxidizing species and the identified secondary organic compounds during the oxidation tests. The detected intermediate converted into end products of CO2 and inorganic anions of SO4−2, NO3−, and PO4−3 at the final stages of the oxidation processes. As antibacterial agents, the two composites exhibit considerable inhabitation zones of about 20 mm against both the Gram-positive Staphylococcus aureus and Gram-negative bacterium Vibrio Sp. The synthetic Co@CH/BE showed the best antibacterial properties with 200 μg/mL as minimum inhibitory against Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

The simple and rapid commercial colloidal gold test strip can only be used for qualitative or semi-quantitative detection, accompanied by weak detectability and false negative experimental results. Herein, a photothermal test strip assay which combined test strip with a portable photothermal card reader was established to achieve quantitative detection with excellent detectability. According to the photothermal effect produced by gold nanoparticles (GNPs) captured on the test line, the signal could be recorded by the reader. Thirteen food hazards including veterinary drug residues and pesticide residues were tested; the photothermal detectability in actual samples were about 23 (methyl parathion), 7 (enrofloxacin), 6 (sarafloxacin), 8 (sulfadiazine), 12 (sulfamethazine), 7 (paraquat), 6 (malachite green), 11 (amantadine), 13 (nitrofurazone), 6 (diethylstilbestrol), 12 (estriol), 21 (estrone), and 26 (17β-estradiol) times better than the visual detectability. Our results demonstrated that the photothermal test strip assay could be used for sensitive, rapid, and quantitative detection of residues of food hazards. [ABSTRACT FROM AUTHOR]

A facile and novel nonenzymatic electrochemical sensor for the detection of methyl parathion (MP) was developed using a glassy carbon electrode modified by copper oxide nanoparticle-deposited waste coffee grounds activated carbon (CuO-NPs/AC/GCE). Activated carbon from waste coffee grounds was prepared using chemical activation method by potassium hydroxide (KOH) and thermal activation with high power microwave-assisted hydrothermal technique from in-house microwave furnace. This method carried out at a lower temperature than which of physical process, providing a high surface area, porosity, and good conductivity. The CuO-NPs on CuO-NPs/AC/GCE can easily bind MP, owing to the high affinity between the Cu on electrode and the thionate sulfur (P=S) or oxon (P=O) groups of MP, resulting in an inhibited redox reaction of Cu and a decrease in the redox peak current of Cu. The nonenzymatic electrochemical sensor, CuO-NPs/AC/GCE, showed excellent electrochemical catalytic activity for the determination of MP compared to that of AC/GCE, CuO-NPs/GCE, and bare GCE by differential pulse voltammetry (DPV). The anodic (Epa) and cathodic peak potentials (Epc) of CuO-NPs on the modified electrode were 0.25 V and − 0.45 V, respectively. The linear ranges were 50–1500 µg L−1, with a low detection limit of 2.42 µg L−1. In addition to being environmentally friendly, the CuO-NPs/AC/GCE sensor demonstrated high selectivity and sensitivity, good stability, and low cost. Further, the proposed nonenzymatic electrochemical sensor has potential applicability for MP detection in soil samples and gave recoveries in the range of 80.18–105.48%. [ABSTRACT FROM AUTHOR]

The present study investigated the effect of nano/microparticles zinc oxide (ZnO-NPs/MPs) on root, vegetative, and flowering induction in medicinal plant Trachyspermum ammi. Powdered ZnO-NPs/MPs were added to soil in concentrations 0, 250, 500, and 1000 mg kg–1. Plants root/shoot weight and length, water content, umbellate and flowers, chlorophyll, carotenoid, oxidants (H2O2, MDA), antioxidants (anthocyanin, phenolics, SOD) were measured. Shoots appeared to be more sensitive to NPs than MPs treatments. ZnO NPs/MPs treatments caused a more consistent result on water content. ZnO-NPs/MPs 500, and 1000 mg kg–1 resulted in toxic responses. ZnO-NPs toxicity effects on growth parameters were more significant than that of MPs, especially on chlorophyll. The decrease in phenolic compound was compensated with increased anthocyanin content under ZnO-NPs/MPs. Both forms of ZnO at all concentrations resulted in zinc content increase compared with the control. ZnO-NPs/MPs 250 mg kg–1 increased plant fresh/dry weight and length of shoots and roots, total chlorophyll, protein and zinc content while reduced oxidant contents. Plants revealed stressed conditions while preferred a non-enzymatic response under NPs. plants' zinc content under NPs was almost similar to micro-treatments. NPs at lower concentrations induced vegetative growth but had a negative effect at higher concentrations. MPs reduced root growth while increased flowering induction. [ABSTRACT FROM AUTHOR]

Methyl parathion (MP), as a typical organophosphorus pesticide, has been widely used in pest control and plant growth regulation. Simultaneously, the problem of pesticide residues also poses a serious threat to the environment and human health. Currently, pesticide residue detection technology still faces great challenges in practical applications due to the problems of expensive facilities and complicated operations in conventional analysis methods. To address these problems, a novel nonenzymatic electrochemical pesticide sensor was reported. A zirconium-based metal organic framework material with terephthalic acid as a ligand (Zr-BDC) was designed to combine with electro-reduced graphene oxides (rGO). The Zr-BDC-rGO nanocomposite contains Zr-OH groups with high affinity for phosphate groups, endowing it with selective recognition and a higher adsorption capacity for MP. Moreover, rGO has a high specific surface area and excellent electron transport capability, making it an excellent functionalized adsorption and substrate material, which could improve the conductivity of the material and achieve a lower detection limit. Upon optimization, this sensor provided a wide linear range from 0.001 to 3.0 μg mL−1 and low limit of detection 0.5 ng mL−1 for MP. This work provides a rapid, sensitive and cost-effective sensing platform for pesticide residue detection. [ABSTRACT FROM AUTHOR]

A novel and sensitive voltammetric nanosensor was developed for the first time for trace level monitoring of favipiravir based on gold/silver core–shell nanoparticles (Au@Ag CSNPs) with conductive polymer poly (3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) and functionalized multi carbon nanotubes (F-MWCNTs) on a glassy carbon electrode (GCE). The formation of Au@Ag CSNPs/PEDOT:PSS/F-MWCNT composite was confirmed by various analytical techniques, including X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and field-emission scanning electron microscopy (SEM). Under the optimized conditions and at a typical working potential of + 1.23 V (vs. Ag/AgCl), the Au@Ag CSNPs/PEDOT:PSS/F-MWCNT/GCE revealed linear quantitative ranges from 0.005 to 0.009 and 0.009 to 1.95 µM with a limit of detection 0.46 nM (S/N = 3) with acceptable relative standard deviations (1.1-4.9 %) for pharmaceutical formulations, urine, and human plasma samples without applying any sample pretreatment (1.12–4.93%). The interference effect of antiviral drugs, biological compounds, and amino acids was negligible, and the sensing system demonstrated outstanding reproducibility, repeatability, stability, and reusability. The findings revealed that this assay strategy has promising applications in diagnosing FAV in clinical samples, which could be attributed to the large surface area on active sites and high conductivity of bimetallic nanocomposite. [ABSTRACT FROM AUTHOR]

The rapid detection of insecticides such as parathion-methyl (PM) requires methods with high sensitivities and selectivities. Herein, a dual catalytic amplification strategy was developed using Fe3O4 nanozyme-supported carbon quantum dots and silver terephthalate metal–organic frameworks (Fe3O4/C-dots@Ag-MOFs) as current amplification elements. Based on this strategy, a novel electrochemical microfluidic paper-based chip was designed to detect PM. Fe3O4/C-dots@Ag-MOFs were synthesised by a hydrothermal method, and a molecularly imprinted polymer (MIP) was then synthesised on the surface of Fe3O4/C-dots@Ag-MOFs using PM as a template molecule. Finally, the reaction zone of a chip was modified with MIP/Fe3O4/C-dots@Ag-MOFs. PM from a sample introduced into the reaction zone was captured by the MIP, which generated a reduction current response at − 0.53 V in a three-electrode system embedded in the chip. Simultaneous catalysis by Fe3O4/C-dots and Ag-MOFs significantly enhanced the signal. The chip had a detection limit of 1.16 × 10−11 mol L−1 and was successfully applied to the determination of PM in agricultural products and environmental samples with recovery rates ranging from 82.7 to 109%, with a relative standard deviation (RSD) of less than 5.0%. This approach of combining a dual catalytic amplification strategy with an MIP significantly increased the sensitivity as well as selectivity of chips and can potentially be used to detect a wide variety of target analytes using microfluidic paper-based chips. [ABSTRACT FROM AUTHOR]

In this work we studied the ability of polystyrene (PS) nanoplastics (NPs) and microplastics (MPs) to transfer benzo(a)pyrene (BaP) to mussel hemocytes and to produce toxic effects in vitro. For this, intracellular fate and toxicity of PS NPs (0.05 μm) and MPs (0.5 and 4.5 μm) alone or with BaP and of BaP alone were assessed. Particles of 0.05 and 0.5 µm largely aggregated in the exposure medium whereas presence of BaP reduced particle aggregation. Cells internalized PS NPs and MPs alone or with BaP and these were found inside and outside lysosomes, depending on their size. PS particles alone or with BaP were cytotoxic to hemocytes only at the highest concentrations tested. The same was true for most sublethal endpoints except for increased phagocytic activity provoked by NPs and 0.5 μm MPs at lower concentrations. Plastic particles appeared to be the main drivers for reduced plasma membrane integrity and increased phagocytic and lysosomal activities whereas BaP appeared to contribute more to reduced cell viability and phagocytosis and increased ROS production and genotoxicity. Overall, PS NPs and MPs can act as carriers of BaP to mussel hemocytes, rising concerns about risks plastics associated to pollutants may pose to aquatic organisms. [ABSTRACT FROM AUTHOR]

This study aimed to find out the effective biotreatment processes of aqueous methyl parathion in stipulations of its biotransformation by potential indigenous mpd strains of Pseudomonas aeruginosa and Fusariumspp. Microbial biotransformation study of methyl parathion in contaminated synthetic wastewater at optimum conditions by P. aeruginosa mpd-5 (at temperature 33 °C, pH 7, under the aerobic condition with inoculum density of 108cells/mL) and by Fusarium spp mpd-1 (at temperature 30 °C, pH 7, under the aerobic condition with inoculum density of 25 mgL−1 dry biomass) was carried out. The major biodegradation compounds formed during the biotreatment process were analyzed by spectral studies using GCMS and FTIR. GCMS analysis of bacterial transformed compounds was p-nitrophenol, dimethylaminophenol, and glycyl-L-proline of 2-(3-methylpiperidino-4-5, 6-benzothiazin-4-one) and 2, 5-piperazinodione 3, 6-bis (2-methylpropyl). And the fungal transformed compounds were observed to be p-nitrophenol, phenol,2,4-Bis(1,1-Dimethylethyl), beta-L-arabinopyranoside-methyl, Cyclobutanethiol, 3-2(4)-thiophenone, dihydro-5-(1-methylethyl), Benzene,1,3-bis(1,1-dimethyl ethyl), Butanoic acid, 2-methyl methyl ester, and L-(+)-Ascorbic acid. The FTIR spectra of the molecule and the products of methyl parathion are observed to be changed in structures. It can be concluded from the aforementioned results and discussions that P. aeruginosa mpd-5 and Fusarium spp mpd-1 can be used in the biotreatment of pesticide wastewater having the high methyl parathion concentration and is possible by the indigenous microbial strains; they utilize as phosphate and carbon source of energy. Hence the strains can be used as a whole microbial cell, or its bioactive metabolites can be applied for the biotreatment of pesticide wastewater and potentially degrade methylparathion. [ABSTRACT FROM AUTHOR]

A sensitive voltammetric sensor has been developed for hazardous methyl parathion detection (MP) using graphene oxide@Ce-doped TiO2 nanoparticle (GO@Ce-doped TiO2 NP) electrocatalyst. The GO@Ce-doped TiO2 NPs were prepared through the sol-gel method and characterized by various physicochemical and electrochemical techniques. The GO@Ce-doped TiO2 NP–modified glassy carbon electrode (GCE) addresses excellent electrocatalytic activity towards MP detection for environmental safety and protection. The developed strategy of GO@Ce-doped TiO2 NPs at GCE surfaces for MP detection achieved excellent sensitivity (2.359 μA μM−1 cm−2) and a low detection limit (LOD) 0.0016 μM with a wide linear range (0.002 to 48.327 μM). Moreover, the fabricated sensor shows high selectivity and long-term stability towards MP detection; this significant electrode further paves the way for real-time monitoring of environmental quantitative samples with satisfying recoveries. [ABSTRACT FROM AUTHOR]

A porous composite magnetic sorbent was developed and used as a solid phase for the solvent-assisted preconcentration of organophosphorus pesticides. The hierarchical porous composite sorbent was composed of polypyrrole thin film coated on the surface of porous alginate beads with embedded magnetite nanoparticles. The pores in the alginate hydrogel beads were produced by carbon dioxide bubbles from the reaction of incorporated calcium carbonate with hydrochloric acid. The porous network was filled with dichloromethane to assist extraction. The fabricated porous composite sorbent was characterized and sorbent fabrication and extraction conditions were optimized to obtain the best extraction performance. The developed sorbent was coupled with GC-MS/MS to determine organophosphorus pesticides in fruit juices and vegetable. Under optimized condition, the developed method provided good linear range of 0.03–200 μg L−1 for dichlorvos, malathion, and fenthion, and 0.075–200 μg L−1 for mevinphos, dimethoate, and parathion methyl, respectively. Limits of detection were in the range 0.010 to 0.025 μg L−1. This method exhibited good relative recoveries in the range 84 to 99% and RSDs lower than 8%. The good stability of the sorbent enabled up to eight cycles of reuse. Graphical abstract [ABSTRACT FROM AUTHOR]

In the scope, the developed novel ZnSeO3/g-C3N4 nanocomposites and characterized in detail. Interestingly, the as prepared nanocomposites examined for the detoxification of organic pollutants like methyl parathion (MP) and cefuroxime drug (CF) under Visible light irradiation. The synthesized ZnSeO3/g-C3N4 nanocomposites were characterized by various techniques such as X-ray diffraction (XRD), fourier transform infra-red (FTIR), UV–Vis diffuse reflectance spectra (DRS/UV–Vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectra (EDX). The photocatalytic studies carried out by UV–Visible Spectroscopy it was exhibited that ZnSeO3/g-C3N4 nanocomposites photocatalyst was a superior photocatalytic performance with the degradation efficiency of an analytic solution of MP and CF observed about 120 mins and 80 mins. The reactive oxidative species are ·OH radical and superoxide radical O2•− involved in the photocatalytic reaction under the source of visible light irradiation by trapping experiments. After the completion of degradation process, the photocatalyst was reused by centrifugation method. The reusability of photocatalyst was highly stable up to eighth cycle. [ABSTRACT FROM AUTHOR]

Patients with ovarian cancer exhibit no clear symptoms. Ovarian cancer can be detected early only through internal diagnosis, ultrasound, and a carcinoma antigen 125 (CA125) tumor index test. More than 60% of patients have advanced ovarian cancer at diagnosis. The traditional chemical fluorescence immunoassay is used to measure CA125 levels; its lowest detection limit is only 35 U mL−1, but it does not adequately demonstrate early symptoms. Moreover, endometriosis, pelvic cavity inflammation, and other gynecological diseases may increase CA125 levels. Therefore, a method for extracting CA125 information is urgently required for ovarian cancer diagnosis. This information can include the glycosylated state of CA125. In this study, a new ultrasensitive electrochemical immunosensor composed of reduced graphene oxide (rGO), gold nanoparticles, thionine chloride, bovine serum albumin, and two antibodies was developed. Through hydrogen peroxide reduction, the sensor can detect glycosylated CA125 from ovarian cancer cells and human blood serum by using differential pulse voltammetry. O2 reacts with H+ that the H+ is formed from altered glycan core structures, producing a strong signal for malignancy detection. With the lowest detection limit of 4.10 pg mL−1 (127 nU mL−1), the sensor can be used for early ovary cancer detection. Furthermore, the results of a clinical test in healthy individuals and patients demonstrated the high selectivity of the immunosensor, and the high-regression-curve rate obtained from human blood serum analysis could be used to distinguish ovarian cancer from other gynecological diseases. This is the first study employing an electrochemical immunosensor to define and identify ovarian cancer to achieve highly specific and accurate detection. [ABSTRACT FROM AUTHOR]

We developed a highly sensitive and selective method for double-signal analysis (fluorescence and ultraviolet–visible spectrophotometry) of organophosphorus pesticides (OPs), based on reversible quenching of graphene quantum dots (GQDs; fluorophores) with silver nanoparticles (AgNPs; absorbers). We used acetylcholinesterase to catalytically convert acetylthiocholine into thiocholine. In turn, by competitive binding to the AgNPs, the produced thiocholine displaces AgNPs from the GQDs and thus induces fluorescence recovery. However, OP analytes inhibit the activity of acetylcholinesterase and, in so doing, retain the silver–graphene nanoparticle complex and fluorescence quenching. The degree of quenching is proportional to the concentration of OPs; the detection limit is as low as 0.017 μg/L. The ultraviolet–visible absorption of GQDs/AgNPs at 390 nm decreases—because of AgNP aggregation that occurs after desorption from the GQDs—and the absorbance is linearly proportional to the OP concentration. Our system has good selectivity to substances that are commonly present in water and vegetables. We successfully applied our method to OP analysis in water, apple, and carrot samples. [ABSTRACT FROM AUTHOR]

The two-step microwave method was used to synthesize zinc oxide nanostars linked to graphene oxide (GO) nanosheets. The material was used to modify a screen printed carbon electrode (SPCE) and then explored as a binder-free electrocatalyst for the electrochemical determination of methyl parathion (MP). The morphology and crystallinity of the material were characterized by various techniques. The modified SPCE shows extraordinary electrochemical performances for sensitive determination of MP. Figures of merit include (a) a wide linear dynamic range (0.03–670 μM), (b) a low detection limit (1.2 nM; at S/N = 3), (c) a comparably low working voltage (−0.69 V vs. Ag/AgCl); and (d) an excellent sensitivity (16.5 μA μM−1 cm−2) that surpasses other modified electrodes. The sensor was successfully applied to the determination of MP, even in the presence of other common electroactive interference, in (spiked) fruits and vegetables. [ABSTRACT FROM AUTHOR]

Surface properties of carbon nanotubes in electrochemical sensors can be dramatically altered depending on chemical groups and structural defects present on the surface. The effect of oxidation on structural integrity of multiwalled carbon nanotubes through acidic (nitric/sulfuric acids) and basic (sodium hydroxide) agents has been studied. Chemical modifications of carbon nanotubes structures were evaluated by Raman, Fourier transform infrared spectroscopy and transmission electronic microscopy. Furthermore, these materials were used to construct sensors for electrochemical determination of pesticide methyl parathion (MP). Under optimized conditions, a calibration curve was obtained for MP determination employing a glassy carbon electrode modified with acidic treated and basic treated carbon nanotubes which showed a linear response ranging from 1.0 × 10–7 to 3.4 × 10–5 M with limits of detection of 3.3 × 10–8 and 3.5 ×10–8 M, respectively. Analytical performance of the electrodes showed similar voltammetric behavior providing good sensitivity for the determination of methyl parathion. [ABSTRACT FROM AUTHOR]

The ligand-stabilized soluble Mn(III) recognized as active intermediate can potentially mediate the attenuation of contaminants. In this study, the abiotic degradation behaviors of methyl parathion in the ligand stabilized Mn(III)-sulfite system were investigated. The results showed that the yield of soluble Mn(III) produced from the redox reaction of MnO2 and oxalic acid was dependent linearly on the dosage of MnO2 and caused the decomposition of methyl parathion up to 50.1% in Mn(III)-sulfite system after 30 minutes. The fitted pseudo-first-order reaction constants of methyl parathion degradation increased with the increasing of the amount of produced Mn(III) but was not effected linearly by the addition of sulfite. Other ligands, including pyrophosphate and oxalic acid, acted as effective complexing agents to stabilize soluble Mn(III), and exhibited competitive effect on methyl parathion degradation with sulfite. The formation of Mn(III)-sulfite complexes is the critical step in the system to produce abundant reactive oxygen species identified as SO3•- to facilitate methyl parathion degradation. The hydrolysis and oxidation of methyl parathion were acknowledged as two primary transformation mechanisms in Mn(III)-sulfite system. These findings indicate that naturally ligands-stabilized soluble Mn(III) can be generated and could oxidatively decompose organophosphate pesticides such as methyl parathion. [ABSTRACT FROM AUTHOR]

In this research, the applicability of NaY/Mn0.5Zn0.5Fe2O4 as a new synthesized nanocomposite adsorbent for the adsorption and degradation of methyl parathion (MP, O,O-dimethyl O-p-nitrophenyl phosphorothioate), an organophosphorus pesticide, is investigated. IThe prepared samples were characterized via SEM-EDAX, TEM, XRD, FTIR, VSM and N2-BET techniques. The role of several experimental factors such as contact time, adsorbent dose and initial concentration of methyl parathion on the removal efficiency of this pesticide were considered and evaluated via 31P nuclear magnetic resonance (31PNMR) spectroscopy. 31PNMR spectroscopy showed that methyl parathion was desirably removed by the NaY/Mn0.5Zn0.5Fe2O4 nanocomposite with a yield of more than 90% under certain optimized conditions. Factors including contact time (80 min), adsorbent dose (0.5 g), and initial pesticide concentration (15 mg/L) were studied and optimized for the reaction. Reaction kinetic status was surveyed using a first order model. The values of the half-life (T1/2) and rate constant (k) were 54.6 min and 0.0127 min−1, respectively. The products of the degradation reaction between methyl parathion and NaY/Mn0.5Zn0.5Fe2O4 were dimethyl phosphorothioic acid (DMPA) and p-nitrophenol (PNP), which are significantly less toxic than the primary pesticide. [ABSTRACT FROM AUTHOR]

The authors report on a surface molecular imprinting strategy for synthesizing magnetic and molecularly imprinted core-shell polymer nanoparticles (MMIPs) with a typical size of 320 nm. The triazophos-imprinted polymer shell on 180-nm magnetite particles (modified with 3-methacryloxypropyl trimethoxysilane) was obtained by radical polymerization of ethylene glycol dimethacrylate in the presence of triazophos, this followed by extractive removal of triazophos. The resulting MMIPs possess large binding capacity, high recognition selectivity, and fast binding kinetics for triazophos. They can be easily separated from a solution by using a magnet. These features result in a convenient and selective solid-phase extraction procedure for triazophos prior to its determination by UV spectrometry or by GC analysis. The method was successfully applied to the extraction and clean-up of triazophos residues in spiked homogenates of vegetables with recoveries in the range of 89.2 ~ 99.0%. The detection limits for triazophos by the UV assay and GC assay are 0.93 nM and 0.32 nM, respectively. [ABSTRACT FROM AUTHOR]

The authors describe an inexpensive electrode for the sensitive amperometric determination of the pesticide methyl parathion. A glassy carbon electrode was modified with a nanocomposite consisting of molybdenum disulfide nanosheets (MoS2) and graphene that was prepared via a hydrothermal process. Its morphology, elemental composition, diffraction, impedance and voltammetric characteristics were studied. The modified electrode displays excellent electrocatalytic ability towards methyl parathion, and the reduction peak current, measured typically at −0.60 V (vs. Ag/AgCl) is related to the concentration of methyl parathion. The effect of concentration, scan rate and solution pH value were optimized. The calibration plot is linear in the 10 nM to 1.9 mM concentration range, with a 3.2 nM detection limit (at a signal-to-noise ratio of 3). The electrode is selective, stable, adequately repeatable and reproducible. The method was successfully applied to the determination of methyl parathion in spiked samples of homogenized apple, kiwi, tomato and cabbage. [ABSTRACT FROM AUTHOR]

A new type of graphene-CoO functionalized porphyrin was synthesized and used for selective and sensitive detection of methyl parathion (MP). CoO nanoparticles were firstly modified onto graphene oxide sheets and the porphyrin/CoO/graphene nanocomposites were then synthesized by self-assembly decoration of anion porphyrin on CoO-modified graphene sheets by π-π stacking. By dexterously controlling the electrochemical reduction variables and optimizing the electrode preparation parameters, with the satisfactory conductivity, strong adsorption toward MP, the developed novel sensor fabricated with the as-synthesized nano-assembly for determination of MP shows some satisfactory properties such as a wide linear concentration range (from 4.0 × 10 M to 2.0 × 10 M), low detection limit (1.1 × 10 M), favorable repeatability, long-time storage stability, and satisfactory anti-interference ability. It also had high precision for the real sample analysis, which indicated the good perspective for field application. [ABSTRACT FROM AUTHOR]

A multifunctional Pseudomonas putida X3 strain was successfully engineered by introducing methyl parathion (MP)-degrading gene and enhanced green fluorescent protein (EGFP) gene in P. putida X4 (CCTCC: 209319). In liquid cultures, the engineered X3 strain utilized MP as sole carbon source for growth and degraded 100 mg L of MP within 24 h; however, this strain did not further metabolize p-nitrophenol (PNP), an intermediate metabolite of MP. No discrepancy in minimum inhibitory concentrations (MICs) to cadmium (Cd), copper (Cu), zinc (Zn), and cobalt (Co) was observed between the engineered X3 strain and its host strain. The inoculated X3 strain accelerated MP degradation in different polluted soil microcosms with 100 mg MP kg dry soil and/or 5 mg Cd kg dry soil; MP was completely eliminated within 40 h. However, the presence of Cd in the early stage of remediation slightly delayed MP degradation. The application of X3 strain in Cd-contaminated soil strongly affected the distribution of Cd fractions and immobilized Cd by reducing bioavailable Cd concentrations with lower soluble/exchangeable Cd and organic-bound Cd. The inoculated X3 strain also colonized and proliferated in various contaminated microcosms. Our results suggested that the engineered X3 strain is a potential bioremediation agent showing competitive advantage in complex contaminated environments. [ABSTRACT FROM AUTHOR]

We report on a biosensor for organophosphate pesticides (OPs) by exploiting their inhibitory effect on the activity of acetylcholinesterase (AChE). A boron-doped diamond (BDD) electrode was modified with a nanocomposite prepared from carbon spheres (CSs; with an average diameter of 500 nm) that were synthesized from resorcinol and formaldehyde, and then were coated with gold nanoparticles (AuNPs) by chemically growing them of the CSs. Compared to a bare BDD electrode, the electron transfer resistance is lower on this new electrode. Compared to an electrode without Au-NPs, the peak potential is negatively shifted by 42 mV, and the peak current is increased by 55 %. This is ascribed to the larger surface in the AuNP-CS nanocomposite which improves the adsorption of AChE, enhances its activity, and facilitates electrocatalysis. Under optimum conditions, the inhibitory effect of chlorpyrifos is linearly related to the negative log of its concentration in the 10 to 10 M range, with a detection limit of 1.3 × 10 M. For methyl parathion, the inhibition effect is linear in the 10 to 10 M range, and the detection limit is 4.9 × 10 M. The biosensor exhibits good precision and acceptable operational and temporal stability. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Whole-cell biocatalyst has the potential to become a cost-effective alternative to conventional enzyme methods for solving ecological and energy issues. However, cytosolic-expressing biocatalyst systems are critically disadvantaged due to the low permeability of the cell membrane. To overcome substrate transport barrier, periplasmic secretion and surface display biocatalysts were developed by expressing signal peptides or anchor proteins in Escherichia coli. In this work, six carriers were compared in regard to whole-cell activity of methyl parathion hydrolase (MPH). Our results indicate that the surface display systems yielded one to three times whole-cell activity than the periplasmic secretion systems. Although periplasmic secretion systems showed generally more stable than surface display systems, surface display appeared more suitable for whole-cell biocatalyst. It should note that the applicability of the DsbA/PhoA/AIDA-I leader to MPH expression is shown here for the first time. In addition, the result provided a useful reference for other whole-cell biocatalyst selection. [ABSTRACT FROM AUTHOR]

A novel poly(malachite green)/graphene nanosheets-nafion (PMG/GNs-NF) composite film-modified glassy carbon electrode was developed to indirectly detect methyl parathion (MP). p-nitrophenol, the alkaline hydrolysis product of MP, was successfully determined at a relatively lower potential using this modified electrode due to the excellent electrocatalytic activity of PMG/GNs-NF composite film. The presence of GNs in the composite film enhanced the stability of PMG and increased the electron transfer rate. The kinetic parameters of modified electrodes were studied. What is more, the optimum experimental parameters affecting response were selected in terms of pH, accumulation potential, accumulation time, scanning cycles during polymerization of malachite green, and alkaline hydrolysis conditions. Under optimum conditions, the chronoamperometric response current was proportional to MP concentration over the range from 0.02 to 1.5 μM with a low-detection limit of 2.0 nM. Finally, the sensor was applied for the determination of MP in real samples, and the results were satisfactory with recoveries from 97.20 to 104.53 %. Due to its simple preparation, good reproducibility, and stability, this developed modified electrode provides a new platform for the detection of organophosphate pesticides. [ABSTRACT FROM AUTHOR]

Methyl parathion hydrolase (MPH) from a methyl parathion-degrading Burkholderia cepacia indigenous to Thailand was purified to apparent homogeneity by three steps of column chromatography using Resource S, Sephadex G100, and Octyl Sepharose 4FF columns. Its molecular mass was determined to be 35 kDa, and the pI to be 8.5. The recombinant plasmid pGT1, containing the MPH-encoding gene, mpdB, cloned into pGEX-4T-2 was over-expressed in Escherichia coli as GST-MPH fusion protein. The recombinant MPH was purified to homogeneity by a single step, using GSTPrep FF affinity column, with the molecular mass identical to that of the native enzyme. The purified enzyme had the specific activity of about 1,600 unit mg protein and the yield of about 75%, a 39-fold increase in recovery compared to that of the native enzyme. The optimal temperature and pH were 25°C and 9.0, respectively. The MPH was stable, with its activity unchanged for 48 h at 4°C, and reduced to 50% after 5 h and to 45% after 48 h at 25°C. The enzyme activity remained 80-90% after 8-15 h at pH 6-7. Cd, Co, and Zn ions at the concentration of 1 mM enhanced the activity; while sodium dodecyl sulfate (SDS), dithiothreitol (DTT) and ethylenediaminetetraacetate (EDTA) reduced it. The enzyme also showed cross reactivity with other insecticides within the organophosphate group, and the kinetic parameters for individual substrates were investigated. Since MPH from B. cepacia has wide potential applications in detoxification and detection of organophosphate compounds, this study provides important basis for its future use. [ABSTRACT FROM AUTHOR]

The sublethal toxic potential of an organophosphorus pesticide, methyl parathion (MP), in altering certain haematological (Hb, Hct, RBC, WBC, mean corpuscular volume (MCV), mean cell haemoglobin (MCH) and mean cell haemoglobin concentration (MCHC)) and biochemical (plasma protein and plasma glucose) parameters in an Indian major carp Catla catla was investigated under static conditions. The LC (96 h) of MP was found to be 0.09 ppm. Fish were exposed to sublethal concentration of MP (0.009 ppm) for a period of 35 days, and the alterations in haematological and biochemical parameters were analysed. A significant decrease was observed in values of haematological parameters like Hb, Hct, RBC and plasma protein throughout the exposure period. However, leucocyte count was gradually increased up to the 21st day and then recovered suddenly showing a significant decrease at the end of the 35th day. MCV and MCH indices showed a significant increase during the study period, whereas MCHC value was more or less similar to control group up to the 21st day, and then a significant decrease was observed in the remaining study period. Plasma glucose values increased up to the 28th day (13.37%) and then declined. The observations presented led us to conclude that the administration of sublethal MP has significant toxic effect on fishes. These parameters could be effectively used as potential biomarkers of interest for MP toxicity to the freshwater fish in the field of environmental biomonitoring. [ABSTRACT FROM AUTHOR]

We report on an electrochemical sensor for the determination of methyl parathion. It is based on an electrode modified with multi-walled carbon nanotubes that were covered with gold nanoparticles (Au-NPs). The vertically aligned array of MWCNTs on a tantalum substrate was coated with Au-NPs by overhead magnetron sputtering deposition. Scanning and transmission electron microscopy and XRD were used to characterize the Au-NP-MWCNTs composite. Cyclic voltammetry and differential pulse voltammetry were employed to evaluate the suitability of the new electrode for the determination of methyl parathion. Under the optimal conditions, the current response of the electrode to methyl parathion is linear in the range from 0.50 to 16.0 mg mL, with a detection limit of 50 μg mL (signal/noise = 3), and the sensitivity is 4.5 times better than that of the plain MWCNTs electrode. We conclude that this method represents a simple, rapid, effective and sensitive approach for the detection of methyl parathion. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Ordered mesoporous carbon (OMC) was synthesized and used to modify the surface of a glassy carbon (GC) electrode. Due to the unique properties of OMC, a decrease in the overvoltage of the reduction potential of methyl parathion (MP) (to ca. 219 mV) and a 76-fold increase in the peak current are observed (compared with a bare GC electrode). The absorption capacity of the surface of the electrode for MP was determined by chronocoulometry. The results show that the Г value of the modified electrode (2.34 × 10 mol cm) is 9.5 times as large as that of the GC electrode (2.47 × 10 mol cm). The new electrode exhibits synergistic electrocatalytic and accumulative effects on MP. MP can be determined by linear sweep voltammetry (LSV) which displays a linear relationship between peak current and MP concentration in the range from 0.09 to 61 μM, with a detection limit as low as 7.6 nM (at an S/N of 3) and after an accumulation at 0 V for 5 min. The electrode was successfully applied to the determination of MP in spiked lake water samples. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Palladium nanoparticles supported on MWCNTs (Pd/MWCNTs) were successfully prepared by a simple ethylene glycol reduction method in an oil bath. An electrochemical sensor based on Pd/MWCNTs nanocomposite-modified glassy carbon electrode was fabricated for the determination of methyl parathion by differential pulse voltammetry measurement. A highly linear response to methyl parathion in the concentration ranging from 0.10 μg mL to 14 μg mL was observed, and a detection limit of 0.05 μg mL was obtained with the calculation based on signal/noise = 3. The present work provides a simple and rapid approach to the detection of methyl parathion. [ABSTRACT FROM AUTHOR]

Stearic acid modified glassy carbon electrode for the sensing of parathion and methyl parathion was fabricated. The electrochemical responses for parathion and methyl parathion were investigated by cyclic voltammetry, differential pulse voltammetry and amperometry. The results on stearic acid modified electrode and bare glassy carbon electrode were compared. Higher sensing current was obtained on stearic acid modified glassy carbon electrode. Analytical characteristics of the sensor such as sensitivity, linear dynamic range, lower detection limit and response time were evaluated. [ABSTRACT FROM AUTHOR]

Pseudomonas sp. strain NyZ402, a native soil organism that grows on para-nitrophenol (PNP), was genetically engineered for the simultaneous degradation of methyl parathion (MP) and ortho-nitrophenol (ONP) by integrating mph (methyl parathion hydrolase gene) from Pseudomonas sp. strain WBC-3 and onpAB (ONP 2-monooxygenase and ONP o-benzoquinone reductase genes) from Alcaligenes sp. strain NyZ215 into the genome of strain NyZ402. Methyl parathion hydrolase (MPH), ONP 2-monooxygenase (OnpA) and o-benzoquinone reductase (OnpB) were constitutively expressed in the engineered strain NyZ-MO. Strain NyZ-MO was free of exogenous antibiotic resistance gene markers and the introduced genes were genetically stable. Degradation experiments showed that strain NyZ-MO could utilize MP or ONP as the sole carbon and energy source, and mineralize 0.1 mM MP–0.1 mM ONP simultaneously. This method may serve as a useful strategy for the construction of engineered strains in the degradation of multiple environmental pollutants. [ABSTRACT FROM AUTHOR]

A novel electrochemical sensor for methyl parathion based on silicate– cetyltrimethylammonium bromide nanocomposite film has been fabricated by electro-assisted deposition onto glassy carbon electrode in one-step via an electrochemical modulation of pH at the electrode/solution interface to promote controlled gelification of tetraethylorthosilicate sol, and was characterized with scanning electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy. The electrochemical sensing of methyl parathion on the film-modified electrode was investigated applying cyclic voltammetry and square wave voltammetry. Compared to the unmodified electrode, the shapes of the redox peaks were improved and the peak currents significantly increased. Experimental parameters such as deposition time, pH value, and accumulation conditions have been optimized. A linear relationship between the peak current and methyl parathion concentration was obtained in the range from 1.0 × 10−7 to 1.0 × 10−4 mol L−1 with a detection limit of 1.04 × 10 −8 mol L−1 ( S/ N = 3) after accumulation at 0 V for 120 s. The film electrode shows great promise for determination of methyl parathion in real samples. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The photodegradation of aqueous solutions containing 0.2 mM methyl parathion has been studied through the optimization of the [H2O2]/[Fe3+] ratio in a Fe3+/H2O2/UV-C flow system of 1.3 L capacity. The decay kinetics and TOC abatement have been analyzed for the experiments performed at pH 3.0 and room temperature. All experiments lead to the total methyl parathion destruction after a few minutes, following a pseudo-first-order decay kinetics. Total mineralization can be reached after 120 min at the optimum ratio found, due to the synergistic effect of the very oxidizing hydroxyl radical (·OH) produced via the Fenton reagent and the effective photodecarboxylation at 253.7 nm. [ABSTRACT FROM AUTHOR]