Acetylcholinesterase inactivating compounds, such as organophosphate (OP) and carbamate (CM) pesticides, are widely used in agriculture to ensure sustainable production of food and feed. As a ...consequence of their applications, they would result in neurotoxicity, even death. In this essence, the development of enzyme inhibition methods still shows great significance as rapid detection techniques for on-site large-scale screening of OPs and CMs. Initially, mechanisms and applications of various enzyme-inhibition-based methods and devices, including optical colorimetric assay, fluorometric assays, electrochemical biosensors, rapid test card, and microfluidic device, are highlighted in the present overview. Further, to enhance the enzyme sensitivity for detection; alternative enzyme sources or high yield enrichment methods (such as abzyme, artificial enzyme, and recombinant enzyme), as well as enzyme reactivation and identification, are also addressed in this comprehensive overview.
•The dual-template imprinting strategy was introduced to synthesize MIP for triazine herbicides and metabolites.•The obtained DMIP possessed multiple types of recognition sites for chloro-, ...thiomethyl- and methoxy- triazines.•DMIP was successfully applied for class-selective extraction of 17 triazine herbicides and metabolites from agro-products.•A high sensitive and accurate DMIP-SPE-LC/MS-MS method was developed and validated.•DMIP-SPE was demonstrated to be reliable, highly class-selective, and cost effective for sample pre-treatment technique.
A novel dual-template molecularly imprinted polymer (DMIP) was prepared with atrazine and prometryn as the template and applied as a class-specific adsorbent for simultaneously selective solid-phase extraction of seventeen triazine herbicides and metabolites from complex matrices. For comparison, a non-imprinted polymer (NIP) and two single-template imprinted polymers (SMIPs) were also synthesized using the same procedure of DMIP, but in the absence of the template (NIP) or with one template (SMIP). Various parameters affecting the extraction performance of DMIP-SPE were investigated in detail. Under the optimum conditions, the enrichment efficiency, class-selectivity and reusability of DMIP-SPE were evaluated. Only DMIP-SPE possessed high affinity and good selective recognition ability for all the seventeen targets including chloro-, thiomethyl- and methoxy- triazines. Further, a DMIP-SPE-LC–MS/MS method was developed for simultaneously determining trace triazine herbicides and metabolites in maize, wheat and cottonseed samples. The method showed good linearity (r>0.9941) in the range of 10-200 μg kg−1, high sensitivity with low limits of detection of 0.5–8.8 μg kg−1, and satisfactory recoveries of 61.3–105.9% with relative standard deviations of 2.1–10.7%. These results highlighted the good application prospect of the multi/dual-template imprinting strategy in the high-throughput analysis of various concerned contaminants in agro-products.
Diabetes is a major chronic disease that jeopardises human health. Resistant starch (RS) is important in controlling diabetes. However, the specific relationship between the starch crystalline ...structure and RS content needs to be further elucidated. In this study, the details of the interactions between different starch molecules (single-amylose and double-helix) and α-amylase were analysed using molecular docking and dynamic simulations. Single-amylose molecules could penetrate deep into the active groove of α-amylase and make full contact with the catalytic triad, and their G3 and G4 glucose residues were firmly bound to the bottom of the active groove throughout the simulation. However, the double-helix molecule in the crystalline region of starch could not fully penetrate to the bottom of the active groove and make full contact with the catalytic triad of α-amylase. This suggests that, without considering other structural factors, the RS content should be positively correlated with relative crystallinity. In addition, starch molecules had strong interactions with α-amylase (approximately 78 kJ/mol) and could form many hydrogen bonds with the amino acid residues of α-amylase such as Thr163, Gln63, and Ile148, which supports the sliding continuum hydrolysis hypothesis of α-amylase. These results explain the intrinsic relationship between the starch hydrolysis efficiency and crystalline structure at the molecular level and provide an important reference for the preparation of RS and elucidation of its mechanism.
•The single-chain starch molecule could penetrate deep into the active groove of α-amylase.•The double-helix molecule could not make full contact with the catalytic triad of α-amylase.•Starch molecules could form many hydrogen bonds of α-amylase.•The RS content should be positively correlated with relative crystallinity.•The results supports the sliding continuum hydrolysis hypothesis of α-amylase.
An electrochemical sensor based on molecularly imprinted polypyrrole (MIPPy) was developed for selective and sensitive detection of the herbicide glyphosate (Gly) in cucumber and tap water samples. ...The sensor was prepared via synthesis of molecularly imprinted polymers on a gold electrode in the presence of Gly as the template molecule and pyrrole as the functional monomer by cyclic voltammetry (CV). The sensor preparation conditions including the ratio of template to functional monomers, number of CV cycles in the electropolymerization process, the method of template removal, incubation time, and pH were optimized. Under the optimal experimental conditions, the DPV peak currents of hexacyanoferrate/hexacyanoferrite changed linearly with Gly concentration in the range from 5 to 800 ng mL
−1
, with a detection limit of 0.27 ng mL
−1
(
S/N
= 3). The sensor was used to detect the concentration of Gly in cucumber and tap water samples, with recoveries ranging from 72.70 to 98.96%. The proposed sensor showed excellent selectivity, good stability and reversibility, and could detect the Gly in real samples rapidly and sensitively.
Graphical abstract
Schematic illustration of the experimental procedure to detect Gly using the MIPPy electrode
The aim of this study was to investigate the protective effect of polyphenol extract from Highland barley (HBPE) on cisplatin (CDDP)-induced oxidative damage and mitochondrial damage in rat kidney. ...The experimental rats were divided into control group, CDDP group, HBPE (600 mg/kg) group, CDDP+HBPE (150 mg/kg) group, CDDP+HBPE (300 mg/kg) group and CDDP+HBPE (600 mg/kg) group. Rats in each group were intragastrically fed with normal saline and corresponding dose of HBPE for 21 d. On the 16th day, CDDP group and CDDP+HBPE group were injected intraperitoneally with CDDP (7.5 mg/kg), and the other groups were injected with the same amount of normal saline. On the 22nd day, the rats were killed and blood samples were taken to detect the contents of blood urea nitrogen (BUN) and creatinine (CrE) in serum, and calculate the kidney index. The kidney samples were used for the measurement of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), hexokinase (HK), and processed for histopathological examinations. The results showed that HBPE improved the abnormalities of serum CrE, BUN, antioxidant and carbohydrate metabolic enzymes in kidney induced by CDDP. HBPE can also reduce the degeneration of renal tubules and glomerular atrophy. Therefore, HBPE has a significant protective effect on oxidative stress injury and mitochondrial damage induced by CDDP in rats.
Herein, field experiment trials were conducted at two different sites (Heilongjiang and Hubei Province) in China to determine the residual levels and dissipation kinetics of metalaxyl-M in rice ...grains, and paddy soil and water. A modified quick, easy, cheap, effective, rugged, and safe “QuEChES” method coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for determination of metalaxyl-M residual levels in different matrices. The method showed an excellent linear response (
R
2
> 0.99) over the concentration range of 0.01–0.50 mg kg
−1
with satisfactory recovery rates in between 76.00 and 111.36%. The limits of quantification (LOQ) were estimated to be 0.010 mg kg
−1
for all matrices. Half-lives of 0.27 to 10.83 days in rice plant, paddy soil, and water indicate that the analyte is easily degraded in the environment within a relatively short time. The terminal residues of metalaxyl-M in rice husks and rice grains were less than 0.05 mg kg
−1
. Dietary risk assessment showed that harvested rice treated with metalaxyl-M would not pose unreasonable risk to humans or the environment.
Glyphosate (GLYP) is a broad-spectrum, nonselective, organic phosphine postemergence herbicide registered for many food and nonfood fields. Herein, we developed a biosensor (Mbs@dsDNA) based on ...carboxylated modified magnetic beads incubated with NH2-polyA and then hybridized with polyT-glyphosate aptamer and complementary DNA. Afterwards, a quantitative detection method based on qPCR was established. When the glyphosate aptamer on Mbs@dsDNA specifically recognizes glyphosate, complementary DNA is released and then enters the qPCR signal amplification process. The linear range of the method was 0.6 μmol/L−30 mmol/L and the detection limit was set at 0.6 μmol/L. The recoveries in tap water ranged from 103.4 to 104.9% and the relative standard deviations (RSDs) were <1%. The aptamer proposed in this study has good potential for recognizing glyphosate. The detection method combined with qPCR might have good application prospects in detecting and supervising other pesticide residues.
A rapid detection method is introduced for residual trace levels of triazophos in water and agricultural products using an immunoassay based on catalytic hairpin self-assembly (CHA). The gold ...nanoparticle (AuNPs) surface was modified with triazophos antibody and sulfhydryl bio-barcode, and an immune competition reaction system was established between triazophos and its ovalbumin-hapten (OVA-hapten). The bio-barcode served as a catalyst to continuously induce the CHA reaction to achieve the dual signal amplification. The method does not rely on the participation of enzymes, and the addition of fluorescent materials in the last step avoids interfering factors, such as a fluorescence burst. The emitted fluorescence was detected at 489/521 nm excitation/emission wavelengths. The detection range of the developed method was 0.01–50 ng/mL for triazophos, and the limit of detection (LOD) was 0.0048 ng/mL. The developed method correlates well with the results obtained by LC–MS/MS, with satisfactory recovery and sensitivity. In sum, the designed method is reliable and provides a new approach to detect pesticide residues rapidly and quantitatively.
Graphical Abstract
Magnetic zeolitic imidazolate framework 67/graphene oxide composites were synthesized by one‐pot method at room temperature for the first time. Electrostatic interactions between positively charged ...metal ions and both negatively charged graphene oxide and Fe3O4 nanoparticles were expected to chemically stabilize magnetic composites to generate homogeneous magnetic products. The additional amount of graphene oxide and stirring time of graphene oxide, Co2+, and Fe3O4 solution were investigated. The zeolitic imidazolate framework 67 and Fe3O4 nanoparticles were uniformly attached on the surface of graphene oxide. The composites were applied to magnetic solid‐phase extraction of five neonicotinoid insecticides in environmental water samples. The main experimental parameters such as amount of added magnetic composites, extraction pH, ionic strength, and desorption solvent were optimized to increase the capacity of adsorbing neonicotinoid insecticides. The results show limits of detection at signal‐to‐noise ratio of 3 were 0.06–1.0 ng/mL under optimal conditions. All analytes exhibited good linearity with correlation coefficients of higher than 0.9915. The relative standard deviations for five neonicotinoid insecticides in environmental samples ranged from 1.8 to 16.5%, and good recoveries from 83.5 to 117.0% were obtained, indicating that magnetic zeolitic imidazolate framework 67/graphene oxide composites were feasible for analysis of trace analytes in environmental water samples.
A luminol-H2O2-HRP chemiluminescence system with high relative luminescent intensity (RLU) and long stabilization time was investigated. First, the comparative study on the enhancement effect of ten ...compounds as enhancers to the luminol-H2O2-HRP chemiluminescence system was carried out, and the results showed that 4-(imidazol-1-yl)phenol (4-IMP), 4-iodophenol (4-IOP), 4-bromophenol (4-BOP) and 4-hydroxy-4'-iodobiphenyl (HIOP) had the best performance. Based on the experiment, the four enhancers were dissolved in acetone, acetonitrile, methanol, and dimethylformamide (DMF) with various concentrations, the results indicated that 4-IMP, 4-IOP, 4-BOP and HIOP dissolved in DMF with the concentrations of 0.2%, 3.2%, 1.6% and 3.2% could get the highest RLU values. Subsequently, the influences of pH, ionic strength, HRP, 4-IMP, 4-IOP, 4-BOP, HIOP, H2O2 and luminol on the stabilization of the luminol-H2O2-HRP chemiluminescence system were studied, and we found that pH value, ionic strength, 4-IMP, 4-IOP, 4-BOP, HIOP, H2O2 and luminol have little influence on luminescent stabilization, while HRP has a great influence. In different ranges of HRP concentration, different enhancers should be selected. When the concentration is within the range of 0~6 ng/mL, 4-IMP should be selected. When the concentration of HRP ranges from 6 to 25 ng/mL, 4-IOP was the best choice. And when the concentration is within the range of 25~80 ng/mL, HIOP should be selected as the enhancer. Finally, the three well-performing chemiluminescent enhanced solutions (CESs) have been further optimized according to the three enhancers (4-IMP, 4-IOP and HIOP) in their utilized HRP concentration ranges.
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