Publications by authors named "Yongxin She"

54 Publications

Enhanced Bio-Barcode Immunoassay Using Droplet Digital PCR for Multiplex Detection of Organophosphate Pesticides.

J Agric Food Chem 2021 Sep 8. Epub 2021 Sep 8.

Department of Entomology & Nematology and the UC Davis Comprehensive Cancer Center, University of California, Davis, Davis, California 95616, United States.

A bio-barcode immunoassay based on droplet digital polymerase chain reaction (ddPCR) was developed to simultaneously quantify triazophos, parathion, and chlorpyrifos in apple, cucumber, cabbage, and pear. Three gold nanoparticle (AuNP) probes and magnetic nanoparticle (MNP) probes were prepared, binding through their antibodies with the three pesticides in the same tube. Three groups of primers, probes, templates, and three antibodies were designed to ensure the specificity of the method. Under the optimal conditions, the detection limits (expressed as IC) of triazophos, parathion, and chlorpyrifos were 0.22, 0.45, and 4.49 ng mL, respectively. The linear ranges were 0.01-20, 0.1-100, and 0.1-500 ng mL, and the correlation coefficients () were 0.9661, 0.9834, and 0.9612, respectively. The recoveries and relative standard deviations (RSDs) were in the ranges of 75.5-98.9 and 8.3-16.7%. This study provides the first insights into the ddPCR for the determination of organophosphate pesticides. It also laid the foundation for high-throughput detection of other small molecules.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jafc.1c03216DOI Listing
September 2021

Novel [email protected] [email protected] core-shell-shell nanospheres for fast extraction and specific preconcentration of nine organophosphorus pesticides from complex matrices.

Food Chem 2021 Dec 26;365:130485. Epub 2021 Jun 26.

Institute of Quality Standard and Testing Technology for Agro-products, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-product Quality and Safety, Ministry of Agriculture, Beijing 100081, PR China.

Herein, a novel core-shell-shell magnetic nanosphere denoted as [email protected]@polymer was fabricated by sequential in situ self-assembly and precipitation polymerization for effective magnetic solid-phase extraction of nine organophosphorus pesticides (OPPs) from river water, pear, and cabbage samples. The integrated [email protected]@polymer featured convenient magnetic separation property and excellent multi-target binding ability. More importantly, the functional polymer coating greatly improved the extraction performance of [email protected] for OPPs, thus facilitating the simultaneous determination of trace OPP residues in real samples. The developed MPSE-LC-MS/MS method exhibited good linearity (R ≥ 0.9991) over the concentration range of 0.2-200 µg L, low limits of detection of 0.0002-0.005 μg L for river water and 0.006-0.185 μg kg for pear and cabbage, satisfactory precision with relative standard deviations ≤ 9.7% and accuracy with recoveries of 69.5-94.3%. These results highlight that the combination of polymers with MOFs has great potential to fabricate excellent adsorbents for high-throughput analysis of various contaminants in complex matrices.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.foodchem.2021.130485DOI Listing
December 2021

Highly sensitive magnetic relaxation sensing method for aflatoxin B1 detection based on Au NP-assisted triple self-assembly cascade signal amplification.

Biosens Bioelectron 2021 Jul 9;192:113489. Epub 2021 Jul 9.

Institute of Quality Standard and Testing Technology for Agro-Products, Chinese Academy of Agricultural Science/Key Laboratory of Agro-Products Quality and Safety of MOA, Beijing, 100081, PR China. Electronic address:

Highly sensitive detection of aflatoxin B (AFB) is of great significance because of its high toxicity and carcinogenesis. We propose a magnetic relaxation sensing method based on gold nanoparticles (Au NPs)-assisted triple self-assembly cascade signal amplification for highly sensitive detection of AFB. Both AFB antibody and initiator DNA (iDNA) are labeled on Au NPs to form Ab-Au-iDNA probe. iDNA is enriched by Au NPs to achieve first signal amplification. Different amounts of Ab-Au-iDNA were bound with AFB antigen by indirect competitive immunoassay, and then hybridization chain reaction event was initiated by iDNA to produce long hybridization chain reaction products to enrich more horseradish peroxidase-streptavidin for the second signal amplification. Dopamine could be rapidly converted to polydopamine by HRP catalysis, which is used as the third signal amplification. The Fe solution, providing paramagnetic ions with a strong magnetic signal, could be adsorbed by the polydopamine due to the formation of coordination bonds of phenolic hydroxyl groups with Fe. This effective interaction between polydopamine and Fe significantly changes the transverse relaxation time signal of Fe supernatant solution, which can be used as a magnetic probe for highly sensitive detection of AFB. The sensor exhibited high specificity and sensitivity with a detection limit of 0.453 pg/mL owing to the Au NP-assisted triple self-assembly cascade signal amplification strategy. It has been successfully employed for AFB detection in animal feed samples with consistent results of enzyme linked immune sorbent assay and high-performance liquid chromatography.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bios.2021.113489DOI Listing
July 2021

Dual-mode detection of organophosphate pesticides in pear and Chinese cabbage based on fluorescence and AuNPs colorimetric assays.

Food Chem 2021 Dec 16;364:130326. Epub 2021 Jun 16.

Agro-products Quality Safety and Testing Technology Research Institute, Guangxi Academy of Agricultural Sciences, 53003 Nanning, China.

Herein, a dual-mode method based on fluorescent and colorimetric sensor was developed for determination of organophosphate pesticides (OPs). In this study, indoxyl acetate (IDA) was hydrolyzed by esterase into indophenol. Indophenol leads to changes in fluorescence signal and aggregation of gold nanoparticles (AuNPs); ultimately changing the color from red to blue. When OPs exist, the formation of indophenol was inhibited. With increasing the concentrations of OPs, the enhancement rate of fluorescence signal decreases, and the color change of AuNPs weakened gradually. The assay was applied for determination of dichlorvos, trichlorfon, and paraoxon, and the limits of detection (LODs) were 0.0032 mg/kg, 0.0096 mg/kg, and 0.0074 mg/kg (fluorometric assay), and 0.0120 mg/kg, 0.0224 mg/kg, and 0.0106 mg/kg (colorimetric assay), respectively. Finally, such a convenient and sensitive sensing assay was successfully applied for quantification of OPs in pear and Chinese cabbage with good recoveries ranged between 80.19 and 116.93%.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.foodchem.2021.130326DOI Listing
December 2021

A sensitive bio-barcode immunoassay based on bimetallic [email protected] nanozyme for detection of organophosphate pesticides in various agro-products.

Food Chem 2021 Nov 15;362:130118. Epub 2021 May 15.

Department of Entomology & Nematology and the UC Davis Comprehensive Cancer Center, Davis, University of California, CA 95616, USA.

Organophosphate pesticides (OPs) are often used as insecticides and acaricides in agriculture, thus improving yields. OP residues may pose a serious threat, duetoinhibitionof the enzymeacetylcholinesterase(AChE). Therefore, a competitive bio-barcode immunoassay was designed for simultaneous quantification of organophosphate pesticide residues using AuNP signal amplification technology and [email protected] catalysis. The AuNP probes were labelled with antibodies and corresponding bio-barcodes (ssDNAs), MNP probes coated with ovalbumin pesticide haptens and [email protected] probes functionalized with the complementary ssDNAs were then prepared. Subsequently, pesticides competed with MNP probes to bind the AuNP probes. The recoveries of the developed assay were ranged from 71.26 to 117.47% with RSDs from 2.52 to 14.52%. The LODs were 9.88, 3.91, and 1.47 ng·kg, for parathion, triazophos, and chlorpyrifos, respectively. The assay was closely correlated with the data obtained from LC-MS/MS. Therefore, the developed method has the potential to be used as an alternative approach for detection of multiple pesticides.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.foodchem.2021.130118DOI Listing
November 2021

Preparation of molecularly imprinted polymer with class-specific recognition for determination of 29 sulfonylurea herbicides in agro-products.

J Chromatogr A 2021 Jun 9;1647:462143. Epub 2021 Apr 9.

State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan, 250353, China; Department of Pharmacology, Faculty of Veterinary Medicine, Cairo University, 12211-Giza, Egypt; Department of Medical Pharmacology, Medical Faculty, Ataturk University, 25240-Erzurum, Turkey. Electronic address:

Molecularly imprinting polymers with high selectivity toward 29 sulfonylurea herbicides were synthesized by precipitation polymerization, using metsulfuron-methyl and chlorsulfuron as the template molecule, 4-vinylpyridine as the function monomer, divinylbenzene as the crosslinking agent, and acetonitrile as porogen. The imprinted polymers were characterized and measured by scanning electron microscopy (SEM) and equilibrium adsorption experiments. The molecularly imprinted polymers displayed specific recognition for the tested 29 sulfonylurea herbicides, and the maximum apparent binding capacity was found to be 18.81 mg/g. The synthesized polymer was used as a solid-phase extraction (SPE) column coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for determination of the tested analytes in agro-products. Within the range of 2-100 μg/L, the tested analytes have achieved a good linear association with correlation coefficient (R) > 0.999. The calculated limits of detection (LODs, S/N=3) as along with limits of quantification (LOQs, S/N=10) were in the ranges of 0.005-0.07 μg/L and 0.018-0.23 μg/L, respectively. Under different spiking levels, the recovery rates were ranged from 74.8% - 110.5%, and the relative standard deviation (RSDs) were < 5.3%. Finally, the feasibility of the proposed methodology was successfully applied for detection of sulfonylurea herbicides in crops, vegetables, and oils samples.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chroma.2021.462143DOI Listing
June 2021

An overview on molecular imprinted polymers combined with surface-enhanced Raman spectroscopy chemical sensors toward analytical applications.

Talanta 2021 Apr 28;225:122031. Epub 2020 Dec 28.

Department of Pharmacology, Faculty of Veterinary Medicine, Cairo University, 12211, Giza, Egypt; Department of Medical Pharmacology, Medical Faculty, Ataturk University, 25240, Erzurum, Turkey. Electronic address:

Surface-enhanced Raman spectroscopy (SERS) is a powerful and high-speed detection technology. It provides information on molecular fingerprint recognition with ultrahigh sensitive detection. However, it shows poor anti-interference capacity against complex matrices. Molecularly imprinted polymers (MIPs) can achieve specific recognition of targets from complex matrices. Through introducing the MIP separation system, the MIP-SERS chemical sensor can effectively overcome the limitation of complex matrix interference, and further improve the stability of sensors for detection. Herein, the materials and structures of integrated MIP-SERS sensors are systematically reviewed, and its application as a sensor for chemical detection of hazardous substances in environmental and food samples has been addressed as well. To broaden the prospects of application, we have discussed the current challenges and future perspectives that would accelerate the development of versatile MIP-SERS chemical sensors.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.talanta.2020.122031DOI Listing
April 2021

Sensitive SERS assay for glyphosate based on the prevention of l-cysteine inhibition of a Au-Pt nanozyme.

Analyst 2021 Feb 27;146(3):956-963. Epub 2020 Nov 27.

Institute of Quality Standard and Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing 100081, P.R China.

Herein, an indirect SERS sensing assay was developed for the determination of glyphosate (Gly) in tap water. The mechanism of detection was based on relieving the inhibitory effect of l-cysteine (l-cys) on a Au-Pt nanozyme by combining Gly with l-cys through divalent copper ions (Cu). In this method, a novel nano-chain-like Au-Ag composite with good repeatability was successfully fabricated to detect SERS signals of oxTMB without disturbing TMB Raman signals. Under optimal conditions, the SERS signal intensity of oxTMB (at 1605 cm) was proportional to the concentration of Gly. The results showed a good linear response over the concentration ranges of 10 μg L to 1000 mg L. The limit of detection and limit of quantitation of Gly were found to be 5 μg L and 10 μg L, respectively. In addition, good anti-interference ability against interfering cations and structural analogues deserves to be mentioned. This SERS assay can be used for detection of Gly in tap water that can meet the needs of practical detection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/d0an01919dDOI Listing
February 2021

Study on the dissipation pattern and risk assessment of metalaxyl-M in rice grains and paddy soil and water by liquid chromatography-tandem mass spectrometry.

Environ Sci Pollut Res Int 2021 Jan 16;28(4):4245-4252. Epub 2020 Sep 16.

Institute of Quality Standards & Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China.

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 > 0.99) over the concentration range of 0.01-0.50 mg kg with satisfactory recovery rates in between 76.00 and 111.36%. The limits of quantification (LOQ) were estimated to be 0.010 mg kg 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. Dietary risk assessment showed that harvested rice treated with metalaxyl-M would not pose unreasonable risk to humans or the environment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-020-10802-3DOI Listing
January 2021

An Overview on the Mechanisms and Applications of Enzyme Inhibition-Based Methods for Determination of Organophosphate and Carbamate Pesticides.

J Agric Food Chem 2020 Jul 2;68(28):7298-7315. Epub 2020 Jul 2.

Agro-products Quality Safety and Testing Technology Research Institute, Guangxi Academy of Agricultural Sciences, 53003, Nanning, China.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jafc.0c01962DOI Listing
July 2020

A "half" core-shell magnetic nanohybrid composed of zeolitic imidazolate framework and graphitic carbon nitride for magnetic solid-phase extraction of sulfonylurea herbicides from water samples followed by LC-MS/MS detection.

Mikrochim Acta 2020 04 20;187(5):279. Epub 2020 Apr 20.

Institute of Quality Standard and Testing Technology for Agro-products, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-product Quality and Safety, Ministry of Agriculture, Beijing, 100081, People's Republic of China.

A "half" core-shell g-CN/[email protected] nanohybrid, in which FeO and zeolite imidazolate framework-8 (ZIF-8) constructed the core-shell structure, was successfully fabricated via a versatile in situ growth strategy. This nanohybrid was employed for simultaneous magnetic solid-phase extraction (MSPE) of trace levels of fifteen target sulfonylurea herbicides (SUHs) in environmental water samples followed by LC-MS/MS detection. CN nanosheets were first prepared by liquid exfoliation of bulk g-CN, after which FeO nanoparticles were uniformly deposited onto the surface of CN nanosheets, and ZIF-8 nanoparticles were grown on the surface of g-CN/FeO by anchoring Zn on g-CN/FeO. Owing to the synergistic effect, the hybridization of CN and ZIF-8 endowed the nanohybrid with higher multi-target adsorption ability for SUHs compared to pure CN or ZIF-8. The separation as well as the enrichment processes were facilitated using FeO as a magnetic core. The influence of various parameters on MSPE efficiency, including adsorbent dosage, extraction time, solution pH, and desorption solvent and its volume, was investigated in detail. Under optimal conditions, the MSPE coupled with LC-MS/MS exhibited good linearity ranging from 0.5 to 100 μg L with correlation coefficients (R) ≥ 0.9919, high sensitivity with low limits of detection (LODs) of 0.005-0.141 μg L and satisfactory recoveries of 67.4-105.5% with relative standard deviations (RSDs) < 9.8%. These results indicate that this method is reliable for the determination of SUHs in different matrices and the in situ growth strategy is a promising approach for constructing effective adsorbents. Graphical abstract Schematic representation of a "half" core-shell magnetic nanohybrid composed of zeolitic imidazolate framework (ZIF-8) and graphitic carbon nitride (g-CN) for magnetic solid-phase extraction (MSPE) of trace level determination of fifteen sulfonylurea herbicides (SUHs) in environmental water samples using LC-MS/MS detection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00604-020-04243-5DOI Listing
April 2020

Magnetic molecularly imprinted specific solid-phase extraction for determination of dihydroquercetin from Larix griffithiana using HPLC.

J Sep Sci 2020 Jun 20;43(12):2301-2310. Epub 2020 Apr 20.

Institute of Quality Standards and Testing Technology for Agri-Products, Chinese Academy of Agricultural Sciences, Beijing, P. R. China.

The naturally occurring quercetin flavonoid, dihydroquercetin, is widely distributed in plant tissues and has a variety of biological activities. Herein, a magnetic molecularly imprinted solid-phase extraction was tailor made for selective determination of dihydroquercetin in Larix griffithiana using high-performance liquid chromatography. Amino-functionalized core-shell magnetic nanoparticles were prepared and characterized using scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, and infrared spectroscopy. The polymer had an average diameter of 250 ± 2.56 nm and exhibited good stability and adsorption for template molecule, which is enriched by hydrogen bonding interaction. Multiple factors for extraction, including loading, washing, elution solvents, and extraction time, were optimized. The limit of detection was 1.23 μg/g. The precision determined at various concentration of dihydroquercetin was less than 4% and the mean recovery was between 74.64 and 101.80%. It has therefore been shown that this protocol can be used as an alternative extraction to quantify dihydroquercetin in L. griffithiana and purify quercetin flavonoid from other complex matrices.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jssc.201901086DOI Listing
June 2020

Development of Water-Compatible Molecularly Imprinted Polymers Based on Functionalized β-Cyclodextrin for Controlled Release of Atropine.

Polymers (Basel) 2020 Jan 6;12(1). Epub 2020 Jan 6.

Institute of Quality Standards & Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing 100081, China.

Herein, a novel method for molecularly imprinted polymers (MIPs) using methacrylic acid functionalized beta-cyclodextrin (MAA-β-CD) monomer is presented, which was designed as a potential water-compatible composite for the controlled release of atropine (ATP). The molecularly imprinted microspheres with pH-sensitive characteristics were fabricated using thermally-initiated precipitation polymerization, employing ATP as a template molecule. The effects of different compounds and concentrations of cross-linking agents were systematically investigated. Uniform microspheres were obtained when the ratio between ATP, MAA-β-CD, and trimethylolpropane trimethacrylate (TRIM) was 1:4:20 (mol/mol/mol) in polymerization system. The ATP loading equilibrium data was best suited to the Freundlich and Langmuir isotherm models. The drug release study was assessed under simulated oral administration conditions (pH 1.5 and 7.4). The potential usefulness of MIPs as drug delivery devices are much better than non-molecularly imprinted polymers (NIPs). The study shows that the prepared polymers are a pH stimuli-responsive system, which controlled the release of ATP, indicating the potential applications in the field of drug delivery.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/polym12010130DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7022701PMC
January 2020

Dissipation pattern and residual levels of boscalid in cucumber and soil using liquid chromatography-tandem mass spectrometry.

J Environ Sci Health B 2020 23;55(4):388-395. Epub 2019 Dec 23.

Institute of Quality Standards & Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing, P.R. China.

To stipulate the rationale of spraying doses and to determine the safe interval period of boscalid suspension concentrate (SC), the degradation dynamics and residual levels were investigated in cucumber and soil using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Field trials were conducted according to Chinese Guideline on pesticide residue trials. Following application, the degradation kinetics was best ascribed to first-order kinetic models with half-life of 2.67-9.90 d in cucumber. Spraying boscalid SC at 1.5-fold the recommended dosage yield terminal residues, which are clearly lower than the maximum residue limit (MRL) established by China (MRL =5 mg.kg) in cucumber. At variance, the dissipation dynamics in soil did not fit to first-order kinetics and the half-life was more than 17 days, the finding which denotes that the degradation behavior of boscalid in soil proceeds slowly. It has therefore been shown that boscalid is safe for use on cucumbers under the recommended dosage.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/03601234.2019.1706374DOI Listing
May 2020

Preparation of core-shell magnetic molecularly imprinted polymers for extraction of patulin from juice samples.

J Chromatogr A 2020 Mar 29;1615:460751. Epub 2019 Nov 29.

Institute of Quality Standards & Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China. Electronic address:

In this study, a novel magnetic molecularly imprinted polymer (MMIP) was prepared by surface imprinting technology using 2-oxin and 6-HNA as dual virtual templates and 4-vinyl pyridine (4-VP) as the functional monomer for extraction of patulin (PAT) from the surface of magnetic nanoparticles. MMIPs were characterized by fourier transformed infrared (FT-IR) spectroscopy, X-ray diffraction, and vibrating sample magnetometry. The results showed that the molecularly imprinted polymer (MIP) was successfully coupled with magnetic nanoparticles and could be used as a magnetic selective recognition material. Moreover, MMIPs have a greater adsorption capacity for PAT than conventional MIPs. The magnetic dispersion solid-phase extraction procedure was optimized and then combined with liquid chromatography-tandem mass spectrometry (MDSPE-LC-MS/MS) for detection of PAT in juice samples. The method showed excellent analytical performance in terms of linearity (ranged between 0.5 μg L and 100 μg Lwith correlation coefficients (r) higher than 0.999) and limit of detection (LOD) (0.1 μg L, S/N = 3). At three spiking concentrations (1, 10, and 50 μg L), the mean recoveries were ranged between 79.4% and 97.9% with relative standard deviations (RSDs) < 4.7% (n = 3).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chroma.2019.460751DOI Listing
March 2020

Assessment of magnetic core-shell mesoporous molecularly imprinted polymers for selective recognition of triazoles residual levels in cucumber.

J Chromatogr B Analyt Technol Biomed Life Sci 2019 11 28;1132:121811. Epub 2019 Oct 28.

Institute of Quality Standards & Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China. Electronic address:

Functional magnetic nanomaterials based on molecular imprinting technique were successfully prepared on the surface of modified FeO. Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometer, and vibrating sample magnetometry were applied for characterization of the synthesized magnetic nanoparticles. The magnetic molecularly imprinted polymers (MMIPs) exhibited satisfactory magnetic response, specific recognition, and excellent adsorption capacity toward triazoles (maximum adsorption capacity of 9202.9 μg g for triadimefon). The obtained MMIPs were further used as magnetic dispersive solid-phase extraction (MDSPE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for detection of 20 triazoles in cucumber spiked at different levels. The mean recoveries were ranged from 79.9% to 110.3% and relative standard deviations (RSDs) were <11.2% (n = 5). Herein, we report a simple, rapid, environmentally friendly, and magnetic stuff recyclable approach for triazoles residual analysis in complicated agricultural products.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jchromb.2019.121811DOI Listing
November 2019

Sensitive and Simple Competitive Biomimetic Nanozyme-Linked Immunosorbent Assay for Colorimetric and Surface-Enhanced Raman Scattering Sensing of Triazophos.

J Agric Food Chem 2019 Aug 16;67(34):9658-9666. Epub 2019 Aug 16.

Institute of Quality Standards and Testing Technology for Agro-Products , Chinese Academy of Agricultural Sciences , Beijing 100081 , People's Republic of China.

The biomimetic enzyme-linked immunosorbent assay (BELISA) is widely used for detection of small-molecule compounds as a result of low cost and reagent stability of molecularly imprinted polymers (MIPs). However, enzyme labels used in BELISA still suffer some drawbacks, such as high production cost and limited stability. To overcome the drawbacks, a biomimetic nanozyme-linked immunosorbent assay (BNLISA) based on MIPs and nanozyme labels was first proposed. For nanozyme labels, platinum nanoparticles (PtNPs) acted as peroxidase by catalyzing the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) into an ideal surface-enhanced Raman scattering (SERS) marker. Blue TMB and bovine serum albumin (BSA)-hapten showed superior selectivity when competing with targets for binding sites on MIPs, named the [email protected] probe. The BNLISA method was employed to detect triazophos with a limit of detection of 1 ng mL via colorimetric and SERS methods. Replacing traditional enzymes with nanozymes for combination with MIPs may bring about a new prospect for other compound analyses.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.jafc.9b03401DOI Listing
August 2019

The determination of patulin from food samples using dual-dummy molecularly imprinted solid-phase extraction coupled with LC-MS/MS.

J Chromatogr B Analyt Technol Biomed Life Sci 2019 Sep 18;1125:121714. Epub 2019 Jul 18.

Institute of Quality Standards & Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China. Electronic address:

A molecularly imprinted polymer (MIP) with specific adsorption for patulin was successfully polymerized by precipitation polymerization using 2-oxindole (2-oxin) and 6-hydroxynicotinic acid (6-HNA) as dummy template molecules, methylacrylic acid (MAA) as a functional monomer, trimethylolpropane trimethacrylate (TRIM) as a crosslinker, 2,2-azobis-(2-methylpropionitrile) (AIBN) as a initiator, and methanol as a porogen solvent. The molecularly imprinted solid phase extraction (MI-SPE) column was prepared using the polymer as a sorbent and applied for the selective extraction of patulin from real samples. The results showed that the MI-SPE method had high selectivity and specific adsorption towards patulin with mean recoveries ranged between 81.3% and 106.3% and a relative standard deviation (RSD) < 4.5%. Additionally, the developed MI-SPE method coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) exhibited good linearity in the range of 1-100 ng mL with correlation coefficients (R) >0.998. The limits of detection (LODs, S/N = 3) were 0.05-0.2 ng g, and the limits of quantification (LOQs, S/N = 10) were 0.2-0.5 ng g. The developed method showed a better purification and higher patulin recovery for real samples than the quick, easy, cheap, effective, rugged, safe "QuEChERS" method.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jchromb.2019.121714DOI Listing
September 2019

A disposable electrochemical sensor based on electrospinning of molecularly imprinted nanohybrid films for highly sensitive determination of the organotin acaricide cyhexatin.

Mikrochim Acta 2019 07 3;186(8):504. Epub 2019 Jul 3.

Key Laboratory of Agro-product Quality and Food Safety, Ministry of Agriculture, Institute of Quality Standards & Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China.

Nanofibrous polyporous membranes imprinted with cyhexatin (CYT) were formed via the ordered distribution of the imprints in electrospun nanofibers. The MIPs have a high mass transfer rate and enhanced adsorption capacity. In addition, a printed carbon electrode with enhanced sensitivity was developed via electrochemical fabrication of reduced graphene oxide (rGO) and gold nanoparticles (AuNPs). The molecularly imprinted sensor exhibits excellent selectivity and sensitivity for CYT. The structure and morphology of the nanohybrid films were characterized by using scanning electron microscopy, atomic force microscopy and chronoamperometry. The sensing performances were evaluated by cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy by using hexacyanoferrate(IV) as an electrochemical probe. The electrode, best operated at a working potential of around 0.16 V (vs. Ag/AgCl), has a linear response in the 1-800 ng mL CYT concentration range and a detection limit of 0.17 ng mL (at S/N = 3). The sensor demonstrated satisfactory recoveries when applied to the determination of CYT in spiked pear samples. Graphical abstract Schematic presentation of the electrochemical sensor for detection of CYT.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00604-019-3631-2DOI Listing
July 2019

Rapid colorimetric determination of the pesticides carbofuran and dichlorvos by exploiting their inhibitory effect on the aggregation of peroxidase-mimicking platinum nanoparticles.

Mikrochim Acta 2019 05 31;186(6):390. Epub 2019 May 31.

Agro-products Quality Safety and Testing Technology Research Institute, Guangxi Academy of Agricultural Sciences, Nanning, 53003, China.

A novel and highly sensitive enzyme inhibition assay was developed for the rapid detection of the organophosphate pesticide dichlorvos and the carbamate pesticide carbofuran. It achieves signal amplification by the secondary catalysis of platinum nanoparticles. Acetylcholinesterase (AChE) is capable of catalyzing the hydrolysis of acetylthiocholine to form thiocholine. Thiocholine causes the aggregation of citrate-capped platinum nanoparticles which then lose their peroxidase-mimicking properties. After addition of pesticides, the activity of AChE is inhibited, less thiocholine is produced, less aggregation occurs, and the peroxidase-mimetic properties are increasingly retained. In the presence of tetramethylbenzidine and HO, a deep blue coloration with an absorption maximum at 650 nm will be formed. The assay was applied to the determination of dichlorvos and carbofuran, and detection limits of 2.3 μg·L and 1.4 μg·L were obtained, respectively. Recovery experiments with spiked tap water and pears gave satisfactory relative standard deviations. Graphical abstract The blue product formed by platinum nanoparticle-catalyzed oxidation of 3,3'5,5'-tetramethylbenzidine (TMB) by HO is reduced if acetylthiocholine (ATCh) is hydrolyzed by acetylcholinesterase (AChE) to form thiocholine. However, if AChE is inhibited by pesticides, color formation will recover.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00604-019-3485-7DOI Listing
May 2019

Preparation of molecularly imprinted polymers coupled with high-performance liquid chromatography for the selective extraction of salidroside from Rhodiola crenulata.

J Chromatogr B Analyt Technol Biomed Life Sci 2019 Jun 16;1118-1119:180-186. Epub 2019 Apr 16.

Institute of Quality Standards and Testing Technology for Agri-Products, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China; Key Laboratory of Agri-food Safety and Quality, Ministry of Agriculture, Beijing 100081, PR China. Electronic address:

Salidroside is one of the bio-active compounds found in Rhodiola crenulata. To find an easy, time saving and efficient way to extract, purify and enrich salidroside from Rhodiola and other natural plants, we prepared a highly selective molecularly imprinted polymer (MIP) for extraction and preconcentration of salidroside using salidroside (SD) as a template, acrylamide (AM) as a functional monomer, ethylene glycol dimethacrylate (EDMA) as a crosslinking monomer, and dimethyl formamide (DMF) as a porogen. The performance of the MIPs was evaluated through selective recognition capacity and adsorption isotherms and kinetics. The results showed that MIPs possessed excellent specific recognition toward SD and could effectively discriminate its structural analogue. The application of the developed MIPs as a selective sorbent for solid-phase extraction (SPE) of SD was also investigated. Under the optimum conditions, a rapid, economical, and efficient method based upon MIP-SPE coupled with high-performance liquid chromatography (HPLC) was developed for the determination of SD in Rhodiola crenulata. The method showed satisfactory recoveries (from spiked real samples at 3 fortification levels of 0.5, 1 and 10 mg L) of 88.74%- 97.64% with relative standard deviations (RSDs) ranging from 2.05%-3.54%. Furthermore, MIP-SPE was successfully used to separate and purify SD from different parts in Rhodiola crenulata and it should be available for determination of salidroside in others herbs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jchromb.2019.04.004DOI Listing
June 2019

Magnetic molecularly imprinted polymers doped with graphene oxide for the selective recognition and extraction of four flavonoids from Rhododendron species.

J Chromatogr A 2019 Aug 25;1598:39-48. Epub 2019 Mar 25.

Lanzhou Institute of Animal Science and Veterinary Pharmaceutics, Chinese Academy of Agricultural Sciences, Lanzhou 730050, Gansu, China. Electronic address:

Herein, a novel magnetic molecularly imprinted polymer doped with reticular graphene oxide ([email protected]@MIPs) was synthesized for the selective recognition and extraction of 4 flavonoids (farrerol, taxifolin, kaempferol, and hyperin) from Rhododendrons species. The [email protected]@MIPs with lamellar membranes showed outstanding adsorption capacity. The 3D cavities complementary to the "shape" of farrerol were "imprinted" on the polymer framework after removal of farrerol template. Competitive binding assays showed that the polymer has a higher selectivity for farrerol compared with other analogues and references. The [email protected]@MIPs as solid-phase extraction adsorbents combined with liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS) was used for selective determination of four flavonoids from Rhododendrons samples. The limits of detection (LOD) were 0.07, 0.08, 0.06, and 0.08 μg L for farrerol, taxifolin, kaempferol, and hyperin, respectively. These results suggest that the prepared [email protected]@MIPs have the potential applicability to extract, purify, and enrich flavonoids from herbs, supplements, and other natural products.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chroma.2019.03.053DOI Listing
August 2019

A Novel CdSe/ZnS Quantum Dots Fluorescence Assay Based on Molecularly Imprinted Sensitive Membranes for Determination of Triazophos Residues in Cabbage and Apple.

Front Chem 2019 18;7:130. Epub 2019 Mar 18.

Key Laboratory of Agro-Products Quality and Safety of Chinese Ministry of Agriculture, Institute of Quality Standard and Testing Technology for Agro-Products, Chinese Academy of Agricultural Science, Beijing, China.

In the present study we have developed a direct competitive CdSe/ZnS quantum dot (QD) fluorescence assay based on micro-array-imprinted membranes for the determination of triazophos in cabbage and apple. The imprinted membranes were directly synthesized on the surface of a 96-well plate by thermal polymerization using triadimefon as the dummy template. Under optimal conditions, the assay showed an excellent linear response over the concentration ranges of 0.1-10,000 μg L with a good coefficient of determination ( = 0.982). The sensitivity (IC) and limit of detection (LOD, expressed as IC) of the developed assay were 3.63 mg L and 0.31 μg L, respectively. The applicability of the developed approach was tested for detecting triazophos in incurred samples. The method showed excellent recoveries (109.6-118.9%) and relative standard deviations (RSDs) between 9.9 and 19.5%. The obtained results correlated well with those obtained by LC-MS/MS ( = 0.9995). The competitive assay using CdSe/ZnS QDs as fluorescence-labeled probe showed good sensitivity, steady and fast response, and excellent anti-interference ability compared to conventional fluorescence-quenching methods. Finally, the feasibility of the proposed methodology was successfully applied for detection of triazophos in real samples.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fchem.2019.00130DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6432856PMC
March 2019

Correction to: A molecularly imprinted polymer with integrated gold nanoparticles for surface enhanced Raman scattering based detection of the triazine herbicides, prometryn and simetryn.

Mikrochim Acta 2019 Mar 5;186(4):215. Epub 2019 Mar 5.

Institute of Quality Standards & Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China.

The published version of this article, unfortunately, contains error. Author name was corrected as "A. M. Abd EI-Aty" - upper case of "i" in "EI-Aty", instead of "A. M. Abd El-Aty" - lower case of "L". Given in this paper is the correct author name.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00604-019-3333-9DOI Listing
March 2019

A Magnetic Zeolitic Imidazolate Framework Nanohybrid for Fast and Efficient Extraction of Clothianidin, Imidacloprid, Acetamiprid, and Thiacloprid in Water.

J Nanosci Nanotechnol 2019 06;19(6):3310-3318

Beijing Technology and Business University, Beijing, 100048, P. R. China.

A magnetic zeolitic imidazolate framework nanohybrid (Fe₃O₄/ZIF-8) was synthesized and applied as an efficient magnetic solid-phase extraction (MSPE) adsorbent for fast adsorption and separation of clothianidin, imidacloprid, acetamiprid, and thiacloprid from various water samples. Fe₃O₄ and ZIF-8 were combined via a simple modified method and the obtained nanohybrid (Fe₃O₄/ZIF-8) showed both excellent adsorption capacity and convenient magnetic property. ZIF-8 was found to play a dominant role in adsorbing the analytes and π-π interaction was found to be the main adsorption mechanism of analytes by Fe₃O₄/ZIF-8. Parameters affecting the MSPE efficiency, such as the Fe₃O₄ amount loaded onto the ZIF-8, salt and pH of the sample solution, extraction time, and the type and volume of desorption solvent, were systematically evaluated. Under the optimum conditions, the developed MSPE coupled with LC-MS/MS achieved good linearities (R² > 0.9940) in the range of 10-800 μg L with low limits of detection (0.03-0.3 μg L) and satisfactory recoveries of 79.5-108.2% with relative standard deviations (RSDs) <10%. The method was successfully applied to monitor various water samples and conclusively highlighted the excellent flexibility and practicability of Fe₃O₄/ZIF-8 for analyzing emerging environmental contaminants in various types of water samples.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1166/jnn.2019.16138DOI Listing
June 2019

A molecularly imprinted polymer with integrated gold nanoparticles for surface enhanced Raman scattering based detection of the triazine herbicides, prometryn and simetryn.

Mikrochim Acta 2019 02 1;186(3):143. Epub 2019 Feb 1.

Institute of Quality Standards & Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China.

A class-specific molecular imprinted polymer (MIP) is described for simultaneous recognition of prometryn and simetryn prior to their determination via a fingerprint signal (at 974 cm and 1074 cm) in the surface enhanced Raman scattering (SERS) spectra that were acquired in the presence of gold nanoparticles. The imprinted nanoparticles were applied to the analysis of rice and wheat samples spiked with both herbicides. The method has fairly good recoveries (72.7-90.9%) with a relative standard deviation of 1.7-7.8%, and a 20 μg·kg limit of detection. The imprint factors (compared to non-imprinted polymers) are 5.3 for prometryn and 4.2 for simetryn (both at 10 μg·mL of the initial solution). Graphical abstract A MIP-SERS method was developed for simultaneous detection of triazine herbicides (prometryn and simetryn) in food samples.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00604-019-3254-7DOI Listing
February 2019

A dummy molecularly imprinted solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry for selective determination of four pyridine carboxylic acid herbicides in milk.

J Chromatogr B Analyt Technol Biomed Life Sci 2019 02 16;1108:65-72. Epub 2019 Jan 16.

Institute of Quality Standards & Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China. Electronic address:

We aim to develop a solid-phase extraction (SPE) based on a dummy molecularly imprinted polymer (MIP) and liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS) for selective determination of four pyridine carboxylic acid herbicides (aminopyralid, picloram, fluroxypyr, and clopyralid) in milk samples. Using picloram as the dummy template, MIP nanocomposites with highly selective recognition and adsorption for the target molecule and its structural analogs were successfully synthesized by precipitation polymerization. Adsorption isotherms and kinetics were used to determine the adsorption performance and specific recognition mechanism of both MIPs and non-molecularly imprinted polymers (NIP). The Scatchard plot analysis revealed that two different binding sites were formed in the MIP with maximum binding capacity (Q) of 1171.8 μg·g and 3022.5 μg·g, respectively. Recovery at three spiking levels of 10, 20, and 50 μg·L ranged between 75.3 and 89.8% with relative standard deviations (RSDs) <14.3%.The limit of detection (LOD) was estimated to be 0.124 μg·L. Finally, the feasibility of the proposed methodology was successfully applied to quantify aminopyralid and another three pyridine carboxylic acid herbicides in milk.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jchromb.2019.01.008DOI Listing
February 2019

Dual-template imprinted polymers for class-selective solid-phase extraction of seventeen triazine herbicides and metabolites in agro-products.

J Hazard Mater 2019 04 23;367:686-693. Epub 2018 Dec 23.

Key Laboratory of Agro-product Quality and Safety, Institute of Quality Standards & Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China. Electronic address:

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, high sensitivity with low limits of detection of 0.5-8.8 μg kg, 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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhazmat.2018.12.089DOI Listing
April 2019

"Off-On" non-enzymatic sensor for malathion detection based on fluorescence resonance energy transfer between β[email protected] and fluorescent probe.

Talanta 2019 Jan 18;192:295-300. Epub 2018 Sep 18.

Agro-products Quality Safety and Testing Technology Research Institute, Guangxi Academy of Agricultural Sciences, 53003 Nanning, China.

Here, we developed a novel non-enzymatic rapid testing method for determination of organophosphate pesticide (malathion) in water. In principle, target molecule can block the Fluorescence resonance energy transfer (FRET) between chemical fluorescent probe (energy donor) and β-cyclodextrin-coated silver nanoparticles (@AgNP) (receptor). The effects of malathion on the dynamics of fluorescent probe and β[email protected] were evaluated and their properties were further characterized. The current methodology showed a good sensitivity of 0.01 μg/mL represented as a limit of detection (LOD) and the calibration curve was linear over the concentration range of 0.1-25 μg/mL. Recovery rate from water samples spiked at 3 different concentration levels (0.3, 0.4, and 0.6 μg/mL) showed satisfactory range between 83% and 101%.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.talanta.2018.09.060DOI Listing
January 2019

Branch-Migration Based Fluorescent Probe for Highly Sensitive Detection of Mercury.

Anal Chem 2018 10 25;90(20):11764-11769. Epub 2018 Sep 25.

Centre of Reproductive Medicine/Family Planning Research Institute, Tongji Medical College , Huazhong University of Science and Technology , Wuhan , Hubei 430030 , P.R. China.

Detection of heavy metals is of great importance for food safety and environmental analysis. Among various heavy metal ions, mercury ion is one of the most prevalent species. The methods for detection of mercury were numerous, and the T-Hg-T based assay was promising due to its simplicity and compatibility. However, traditional T-Hg-T based methods mainly relied on multiple T-Hg-T to produce enough conformational changes for further detection, which greatly restrained the limit of detection. Hence, we established a branch-migration based fluorescent probe and found that single T-Hg-T could produce strong signals. The sensing mechanism of our method in different reaction modes was explored, and the detection limits were determined to be 18.4 and 14.7 nM in first-order reaction mode and mixed reaction mode, respectively. Moreover, coupled with Endonuclease IV assisted signal amplification, the detection limit could be 1.2 nM, lower than most DNA based fluorometric assays. For practicability, the specificity of our assay toward different interfering ions was investigated and detection of Hg in deionized water and lake water was also achieved with similar recoveries compared to those of atomic fluorescence spectrometry, which demonstrated the practicability of our method in real samples. Definitely, the proposed branch migration probe would be a promising substitution for current DNA probes based on recognition of multiple T-Hg-T and we anticipate it to be widely adopted in food and environmental analysis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.analchem.8b03547DOI Listing
October 2018
-->