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Majdinasab M.,Chinese Academy of Agricultural Sciences | Majdinasab M.,Isfahan University of Technology | Sheikh-Zeinoddin M.,Isfahan University of Technology | Soleimanian-Zad S.,Isfahan University of Technology | And 12 more authors.
Food Control | Year: 2015

Immunochromatographic assays (ICAs) are considered as a suitable diagnostic tool for the detection ofmycotoxins. Mycotoxins and especially, ochratoxin A are analytes with more demanding sensitivity requirements. To enhance the sensitivity of current immunochromatographic assays for ochratoxin A(OTA), a novel sensitive ICA was developed in this study. In the assay, microspheres enclosing fluorescent europium (III) [Eu(III)] nanoparticles (EuNPs) were used as a label for OTA monoclonal antibody (OTA-mAb) conjugation. Accordingly, assay was called time-resolved fluorescent immunochromatographic assay (TRFICA). The test strip was composed of three parts: a sample pad, nitrocellulose membrane and an absorbent pad. As for detection, a proper concentration of conjugated microspheres was pipetted into the microtube and sample extract was added to it. Then the strip was inserted into the tube and the fluid flow along the strip. The TRFICA results were obtained in 8min and read by a portable TRFICA strip reader. The established method allows quantitative determination of OTA with limit of detection as low as 1.0μgkg-1 in the samples. For validation, spiked samples including wheat, maize, soybean and rice were respectively assayed by TRFICA and a standard high performance liquid chromatography equipped with a fluorescence detector (HPLC-FLD), and good agreement of results was obtained between two methods. © 2014 Elsevier Ltd.

Wang X.,Chinese Academy of Agricultural Sciences | Wang X.,Key Laboratory of Biology and Genetic Improvement of Oil Crops | Wang X.,Laboratory of Risk Assessment for Oilseeds Products Wuhan | Li P.,Chinese Academy of Agricultural Sciences | And 3 more authors.
Food Chemistry | Year: 2015

An automated, size-exclusion solid phase extraction (SPE)-UPLC-MS/MS protocol without pre-treatment of samples was developed to screen for four mycotoxins (OTA, ZEN, AFB1, and AFM1) in liquid milk and milk powder. Firstly, a mixed macropore-silica gel cartridge was established as a size-exclusion SPE column. The proposed methodology could be a candidate in green analytical chemistry because it saves on manpower and organic solvent. Permanent post-column infusion of mycotoxin standards was used to quantify matrix effects throughout the chromatographic run. Matrix-matched calibration could effectively compensate for matrix effects, which may be caused by liquid milk or milk powder matrix. Recovery of the four mycotoxins in fortified liquid milk was in the range 89-120% and RSD 2-9%. The LOD for the four mycotoxins in liquid milk and milk powder were 0.05-2 ng L-1 and 0.25-10 ng kg-1, respectively. The LOQ for the four mycotoxins in liquid milk and milk powder were 0.1-5 ng L-1 and 0.5-25 ng kg-1, respectively. © 2014 Elsevier Ltd. All rights reserved.

Yu L.,Chinese Academy of Agricultural Sciences | Yu L.,Key Laboratory of Biology and Genetic Improvement of Oil Crops | Yu L.,Quality Inspection and Test Center for Oilseeds Products | Li P.,Chinese Academy of Agricultural Sciences | And 14 more authors.
Journal of Chromatography A | Year: 2013

In this paper, graphene oxide (GO) was synthesized and specifically selected by centrifugation to extract four aflatoxins (B1, B2, G1, and G2) as an effective adsorbent. Then, the amount of aflatoxins was quantitatively measured by high-performance liquid chromatography (HPLC). The GO was characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), and ultraviolet (UV) spectrophotometer. Several parameters that could affect the extraction efficiency, including the GO amount, methanol concentration in the extraction solvent, spiked amount, extraction time, and elution cycle, were also investigated and optimized in this work. Under optimal conditions, good linear relationships were achieved with the correlation coefficient (r) ranging from 0.99217 to 0.99995. The detection limit of this method for the four aflatoxins ranged from 0.08 to 0.65ng/g. Finally, the proposed method has been successfully applied to determine aflatoxins in peanut samples. The results show that the recoveries of the four aflatoxins range from 85.1% to 100.8% with the relative standard deviations between 2.1% and 7.9%. © 2013 Elsevier B.V.

Wang Y.,Chinese Academy of Agricultural Sciences | Wang Y.,Key Laboratory of Biology and Genetic Improvement of Oil Crops | Wang Y.,Key Laboratory of Detection for Mycotoxins | Wang Y.,Laboratory of Risk Assessment for Oilseeds Products | And 12 more authors.
Analytical Chemistry | Year: 2013

Anti-idiotypic antibodies recognize the antigenic determinants of an antibody, thus they can be used as surrogate antigens. Single-domain antibodies from camlid heavy-chain antibodies with the benefit features of small size, thermostability, and ease in expression, are leading candidates to produce anti-idiotypic antibodies. In this work, we constructed an antibody phage library from the mRNA of an alpaca immunized with an antiaflatoxin monoclonal antibody (mAb) 1C11. Three anti-idiotypic VHH antibodies were isolated and applied to immunoassay toward aflatoxin as a coating antigen. The best immunoassay developed with one of these VHH antibodies shows an IC50 of 0.16 ng/mL toward aflatoxin B1 and cross-reactivity toward aflatoxin B2, G1, and G2 of 90.4%, 54.4%, and 37.7%, respectively. The VHH-based immunoassay was successfully applied to the analysis of peanuts, corn, and rice, which are the predominant commodities regularly contaminated by aflatoxins. A good correlation (r2 = 0.89) was found between the data obtained from the conventional ELISA and the ELISA based on a VHH coating antigen for the analysis of aflatoxins in peanuts and feedstuff. The use of biotechnology in developing the surrogate, the absence of standard aflatoxin and organic solvents in the synthesis procedures, and the reproducibility of the VHH antibody makes it an ideal strategy for replacing conventional synthesized antigens. © 2013 American Chemical Society.

Wang Y.,Chinese Academy of Agricultural Sciences | Wang Y.,Key Laboratory of Biology and Genetic Improvement of Oil Crops | Wang Y.,Key Laboratory of Detection for Mycotoxins | Wang Y.,Laboratory of Risk Assessment for Oilseeds Products Wuhan | And 9 more authors.
Journal of Agricultural and Food Chemistry | Year: 2013

To search for an alternative to using protein conjugated aflatoxin as a coating antigen in aflatoxin detection by an ELISA method, a random-8-peptide library was constructed and used as a source of peptides that mimic aflatoxins (termed as mimotopes). Five mimotope peptides were obtained by panning-elution from the library and were successfully used in an indirect competitive ELISA for analyzing total aflatoxin concentration. The assay exhibited an IC50 value of 14 μg/kg in samples (with 1 in 7 dilution of sample extract) for aflatoxins. The linear range is 4-24 μg/kg. Further validation indicated relatively good recovery (60-120%) in peanut, rice and corn. Natural contaminated samples (peanut and feedstuff) were analyzed for aflatoxin concentration by both conventional ELISA and phage ELISA. The results showed good correlation. It can be concluded that the mimotope preparation is an effective substitute for the aflatoxin based coating antigen in ELISA and can be used in real sample analysis. © 2013 American Chemical Society.

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