Beijing WDWK Biotech Co.

Beijing, China

Beijing WDWK Biotech Co.

Beijing, China
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Tao X.,China Agricultural University | Yu X.,China Agricultural University | Zhang D.,China Agricultural University | Shi W.,China Agricultural University | And 7 more authors.
Journal of the Science of Food and Agriculture | Year: 2014

BACKGROUND: A rapid one-step chemiluminescent competitive indirect enzyme-linked immunosorbent assay (CL-ciELISA) for florfenicol (FF) and its major metabolite florfenicol amine (FFA) residues in animal meat products has been developed. RESULTS: The 50% binding inhibition (IC50) values of the method were 0.195 μg kg-1 for FFA and 0.24 μg kg-1 for FF under optimum conditions. The cross-reactive rates for FF and FFA were 100.0% and 81.2%, respectively. FF and FFA were easily extracted from animal meat product with an FF/FFA extraction buffer, obtaining recoveries of 81.8-92.0% (FF) and 77.2-100% (FFA). The whole one-step CL-ciELISA test can be accomplished within 40 min in theory. The detection limits (LODs) of the assay were 0.98 μg kg-1 for FF and 0.80 μg kg-1 for FFA in animal meat samples. Finally, field animal meat samples were analyzed with the CL-ciELISA method, and the results correlated well with those obtained using traditional ELISA and a previously reported liquid chromatographic-tandem mass spectrometric method. CONCLUSION: The combined results confirmed the utility of this faster one-step CL-ciELISA for simultaneous trace analysis of FF and FFA. To date, this is the most rapid developed ELISA and CL-ELISA method for detection of FF and FFA. © 2013 Society of Chemical Industry.


Tao X.,China Agricultural University | Jiang H.,China Agricultural University | Yu X.,China Agricultural University | Zhu J.,China Agricultural University | And 5 more authors.
Drug Testing and Analysis | Year: 2013

A competitive, direct, chemiluminescent immunoassay based on a magnetic beads (MBs) separation and gold nanoparticles (AuNPs) labelling technique to detect chloramphenicol (CAP) has been developed. Horseradish peroxidase (HRP)-labelled anti-CAP monoclonal antibody conjugated with AuNPs and antigen-immobilized MBs were prepared. After optimization parameters of immunocomplex MBs, the IC50 values of chemiluminescence magnetic nanoparticles immunoassay (CL-MBs-nano-immunoassay) were 0.017 μg L-1 for extract method I and 0.17 μg L-1 for extract method II. The immunoassay with two extract methods was applied to detect CAP in milk. Comparison of these two extract methods showed that extract method I was advantageous in better sensitivity, in which the sensitivity was 10 times compared to that of extract method II, while extract method II was superior in simple operation, suitable for high throughout screen. The recoveries were 86.7-98.0% (extract method I) and 80.0-103.0% (extract method II), and the coefficients of variation (CVs) were all <15%. The satisfactory recovery with both extract methods and high correlation with traditional ELISA kit in milk system confirmed that the immunomagnetic assay based on AuNPs exhibited promising potential in rapid field screening for trace CAP analysis. © 2013 John Wiley & Sons, Ltd.


Tao X.,China Agricultural University | Shen J.,China Agricultural University | Cao X.,China Agricultural University | Wang Z.,China Agricultural University | And 2 more authors.
Analytical Methods | Year: 2014

Two novel chemiluminescence immunoassays using the horseradish peroxidase (HRP)-luminol chemiluminescence system and two different enzymatic systems - HRP and alkaline phosphatase (ALP) chemiluminescence systems - were established for simultaneous detection of chloramphenicol (CAP) and clenbuterol (CLE) residues in milk. Milk samples were detected utilizing the two hybrid chemiluminescence immunoassays, with limits of detection (LODs) of 0.006 μg L-1 for CAP and 0.02 μg L-1 for CLE (Scheme 1A), 0.008 μg L -1 for CAP and 0.023 μg L-1 for CLE (Scheme 1B), respectively. The recoveries for CAP and CLE in individual and co-spiked samples were found to be between 80.0% and 96.7%. The applicability of the proposed method has been validated by determining CAP and CLE in field milk samples with satisfactory results. Thereafter, the developed hybrid chemiluminescence immunoassays can be used as reliable, rapid, and cost effective screening techniques for the simultaneous determination of CAP and CLE residues in milk. © 2014 The Royal Society of Chemistry.


Tao X.,China Agricultural University | Chen M.,China Agricultural University | Jiang H.,China Agricultural University | Shen J.,China Agricultural University | And 4 more authors.
Analytical and Bioanalytical Chemistry | Year: 2013

A chemiluminescent competitive indirect enzyme-linked immunosorbent assay, based on a mutant single-chain variable fragment (scFv), was developed to detect a broad range of fluoroquinolones (FQs) in fish and shrimp matrices. In this study, the best scFvC4A9H1-mut2 was adopted, which showed 10-fold improved affinity to sarafloxacin (SAR), difloxacin (DIF), and trovafloxacin (TRO), while the affinity to other FQs was fully inherited from wild-type scFvC4A9H1. In the optimized generic test, scFvC4A9H1-mut2 in combination with norfloxacin-ovalbumin conjugate and horseradish peroxidase-labeled anti-c-myc 9E10 antibody showed 50 % binding inhibition (IC50) at 0.12 μg kg-1 for norfloxacin in buffer. Screening for the class of FQ antibiotics is accomplished using a simple, rapid extraction carried out with ethanol/acetic acid (99:1, v/v). This common extraction was able to detect 20 FQ residues such as s ciprofloxacin (CIP), danofloxacin, DIF, enoxacin, enrofloxacin (ENR), fleroxacin, amifloxacin, flumequine, levofloxacin, lomefloxacin hydrochloride, marbofloxacin, norfloxacin (NOR), ofloxacin, orbifloxacin, pazufloxacin, pefloxacin-d5 (PEF), prulifloxacin, SAR, sparfloxacin, and TRO in fish and shrimp. The limit of detection (LOD) for NOR was 0.2 μg kg-1 and the LODs for CIP and ENR were all <0.2 μg kg-1. Values of LODs inferred from the cross-reactivity data will range from approximately 0.23 μg kg-1 for PEF to 2.1 μg kg-1 for TRO. Field fish and shrimp samples were analyzed and compared to the results obtained from liquid chromatography tandem mass spectrometric method. All five instances (from 0.25 to 15.6 μg kg -1) in which FQs were present at concentrations near or above the assay LOD were identified as positive by the newly developed assay, demonstrating the usefulness of this assay as a screening tool. [Figure not available: see fulltext.] © 2013 Springer-Verlag Berlin Heidelberg.


Haiyang J.,China Agricultural University | Wenjun W.,Beijing WDWK Biotech Co. | Jinghui Z.,China Agricultural University | Xiaoqi T.,China Agricultural University | And 12 more authors.
Luminescence | Year: 2014

A chemiluminescent enzyme immunoassay (CLEIA) was compared to an ultraperformance liquid chromatography tandem mass spectroscopy (UPLC-MS/MS) procedure for the analysis of zeranol and its metabolites in bovine tissue samples. Apparent recoveries from fortified samples by both methods were comparable at 0.5-4.0 μg/kg and a significant correlation was obtained. For CLEIA analysis, hapten mimicking the analyte was first synthesized and conjugated with the carrier protein bovine serum albumin as the immunogen to produce monoclonal antibody. The obtained antibody showed extensive cross-reactivity toward zeranol metabolites (zearalanone). The limit of detection of CLEIA and UPLC-MS/MS was 0.05 μg/kg and 0.5 μg/kg, respectively. Recoveries of both methods for fortified samples were higher than 75.0% with the coefficient of variation less than 15%. These results indicated that the combination of screening with CLEIA and confirmation with UPLC-MS/MS for zeranol and its metabolites would be a reliable method for a large number of bovine samples. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.


Tao X.,China Agricultural University | Wang W.,Beijing WDWK Biotech Co. | Wang Z.,China Agricultural University | Cao X.,China Agricultural University | And 5 more authors.
Luminescence | Year: 2014

In this study, a high sensitivity chemiluminescence enzyme immunoassay (CLEIA) based on novel enhancers was developed. Under optimal conditions, we developed an enhanced chemiluminescence reaction (ECR) catalyzed by horseradish peroxidase (HRP-C) in the presence of 3-(10'-phenothiazinyl) propane-1-sulfonate (SPTZ) and 4-morpholinopyridine (MORP) as enhancers. The limit of detection of the newly prepared chemiluminescent cocktail for HRP was 0.33 pg/well, which is lower than that of commercial Super Signal substrate. The results showed that this novel chemiluminescent cocktail can significantly increase the light output of HRP-catalyzed ECR, which can be translated into a corresponding improvement in sensitivity. Similar improvements were observed in CLEIA for the determination of chloramphenicol in milk. In addition, the ECR of N-azoles as secondary enhancer was also presented. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.


Tao X.,China Agricultural University | Jiang H.,China Agricultural University | Yu X.,China Agricultural University | Zhu J.,China Agricultural University | And 5 more authors.
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment | Year: 2013

A novel chemiluminescent immunoassay utilising two types of primary antibodies (murine monoclonal antibody and rabbit polyclonal antibody) and two types of horseradish peroxidase-labelled secondary antibodies was established for simultaneously detecting multiple amphenicol residues in ham sausage. After combining the extract procedure of the target amphenicol into one simplified method, this hybrid chemiluminescent immunoassay could screen chloramphenicol (CAP), florfenicol (FF) and its metabolite florfenicol amine (FFA) at the same time by adding the corresponding secondary antibody. Ham sausage samples were analysed by using this hybrid immunoassay, with LODs of CAP being 0.01 μg kg-1, of FF being 2.8 μg kg-1 and of FFA being 3.0 μg kg-1. The applicability of the proposed method has been validated by determining CAP, FF and FFA in ham sausage samples with satisfactory results. Good recoveries and high correlation with traditional enzyme-linked immunosorbent assay and LC-MS/MS results illustrated that the developed hybrid chemiluminescent immunoassay could screen high-throughput ultra-trace amphenicol residues effectively at one time. © 2013 Copyright Taylor & Francis.


Jiang W.,China Agricultural University | Luo P.,China National Institute for Nutrition and Food Safety | Wang X.,China Institute of Veterinary Drug Control | Chen X.,China Agricultural University | And 5 more authors.
Food Control | Year: 2012

A sensitive and specific enzyme-linked immunosorbent assay (ELISA) for the detection of 1-amino-hydantoin (AHD) is described. AHD, the marker residue for nitrofurantoin, is a tissue bound toxic metabolite. To monitor the illegal use of nitrofurantoin, a monoclonal antibody-based ELISA method was developed to detect AHD residue in animal tissues. The highly specific antibody against AHD was prepared by monoclonal antibody technology. The antibody exhibited negligible cross reactivity with other nitrofurans, their metabolites and derivatives, and 50% inhibitory concentration was 0.68 μg/L. The limit of detection in four kinds of animal tissues were all below 0.2 μg/kg and recoveries ranged from 75% to 116.7% for fortified samples at levels of 0.2-5 μg/kg with coefficient of variation values below 15%. Analysis of natural contaminated samples by the ELISA method gave similar results to those of the liquid chromatography-tandem mass spectrometry method. These results indicate the ELISA method is suitable for the detection of AHD residue in animal tissues. © 2011 Elsevier Ltd.


Tao X.,China Agricultural University | Zhu J.,China Agricultural University | Niu L.,Beijing WDWK Biotech Co. | Wu X.,Beijing WDWK Biotech Co. | And 4 more authors.
Analytical Letters | Year: 2012

A competitive indirect chemiluminescent enzyme-linked immunoassay (CL-ELISA) for chloramphenicol (CAP) residues in milk and chicken muscle has been developed. Due to the unique characteristic of the polyclonal antibody, special reaction system and modified extract method, then after optimization (concentration of Tween-20, concentration of PB and pH, incubation time, and temperature), the method gave a detection limit of 0.92 ng/L and a detection range of 3.16-3035 ng/L, with the IC50 of 17.29 ng/L in optimum condition and real sample matrix. When CAP was spiked in milk and chicken muscle at levels of 5-100 ng/L, recoveries ranged from 104.9%-114.8% and 101.0%-118.8%, with coefficients of variation of 3.0%-14.6% and 9.5%-14.4%, respectively. In an actual chicken muscle residue study, although the extract of samples diluted 10-fold, or even 100-fold, which represents extremely lower concentration of CAP, the results obtained by CL-ELISA correlated well with those obtained by gas chromatography with microcell electron capture detector. The developed method is therefore suitable for screening of ultratrace CAP residues in milk and chicken muscle samples. © 2012 Copyright Taylor and Francis Group, LLC.


Tao X.,China Agricultural University | Jiang H.,China Agricultural University | Zhu J.,China Agricultural University | Wang X.,China Institute of Veterinary Drug Control | And 5 more authors.
Food and Agricultural Immunology | Year: 2014

A competitive, direct, chemiluminescent enzyme-linked immunosorbent assay (CL-ELISA) for chloramphenicol (CAP) residues in milk, milk powder, honey, eggs and chicken muscle has been developed. The method gave a detection limit of 0.7 ng L-1 and a linear range of 2.1-92.4 ng L-1, with the IC50 of 13.6 ng L-1 under optimal conditions, dramatically better than any previously reported ELISA method for CAP detection. Spiked at levels of 5-60 ng L-1 in different food samples, recoveries were in the range of 72.1-116.0%, with coefficient of variations of 4.2-20.2%. In a study of incurred residues, the chicken muscle samples diluted 5-, 10- and 20-fold, results obtained by CL-ELISA correlated well with those obtained by gas chromatography with microcell electron capture detector and traditional ELISA. The developed CL-ELISA method is, therefore, suitable for rapid screening trace CAP residues in food samples. © 2013 Taylor & Francis.

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