Guangzhou, China
Guangzhou, China

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Zhang S.,South China University of Technology | Zhang S.,Wondfo Biotech Co. | He X.-W.,South China University of Technology | Liu X.-Y.,Wondfo Biotech Co. | And 4 more authors.
Modern Food Science and Technology | Year: 2014

In order to establish a simple, rapid, sensitive, and specific method to detect Listeria monocytogenes, in this study, immunomagnetic beads were prepared by coupling anti-L. monocytogenes monoclonal antibody with magnetic beads. The fluorescence immunochromatographic strips were composed of anti-L. monocytogenes polyclonal antibody and mouse IgG marked by fluorescent microspheres as the detection antibody, anti-L. monocytogenes polyclonal antibody as the test line, and the goat anti-mouse IgG secondary antibody as the control line. Immunomagnetic separation was combined with a fluorescence immunochromatographic assay, and this method was applied to rapidly detect L. monocytogenes. The results showed that the detection limit of fluorescence immunochromatographic strips for pure cultures was 4×105 CFU/mL. For the joint detection method using samples concentrated 10- and 100-fold, the detection limits of pure culture samples were 4×104 CFU/mL and 1×104 CFU/mL, respectively. The joint detection method showed good specificity, and no cross-reactivity of the 10 strains kept in the laboratory was observed. The detection limit of artificially contaminated samples was also 1×104 CFU/mL and was not reduced compared with pure cultures. This method is of great value for rapid on-site detection of L. monocytogenes in food products. ©, 2014, South China University of Technology. All right reserved.


Hu F.,South China University of Technology | Xu Q.-H.,South China University of Technology | Li W.-M.,South China University of Technology | Li W.-M.,Wondfo Biotech Co. | He X.-W.,South China University of Technology
Modern Food Science and Technology | Year: 2013

By optimizing the ELISA working conditions, an indirect competitive ELISA method was established for detection of salbutamol (SAL). The most suitable working condition of ELISA was obtained by phalanx titration method which is used to calculate the most optimal dilution of the coating antigen, antiserum, and HRP secondary antibody. Serial diluted SAL of the standard solution was set as the detection object and the standard curve of ELISA was plotted. The most optimal dilution of the coating antigen, antiserum, and HRP secondary antibody were 1: 2000, 1: 4000 and l: 6000, respectively. The standard curve of ELISA indicated that the linear determination was 0.5~20 ng/mL with 50% inhibitive concentration (IC50) of 2.33 ng/mL. The ELISA plates produced by Shenzhen Jincanhua Limited was chosen as the the best plate. And the optimization conditions were as follows: envelope liquid 0.05 mol/L, pH 9.6 of carbonate buffer solution and blocking solution 1% BSA + PBST. The standard substance was preparedwith combination solution Antibody diluent was of sample 1 and enzyme mark two anti diluents was of sample 3. coloration time was 15 minutes. This method for SAL detection was sensitive, specific, simple operation, suitable for screening large numbers of samples.


Zhang S.,South China University of Technology | Xu Q.-H.,South China University of Technology | Li W.-M.,South China University of Technology | Li W.-M.,Wondfo Biotech Co. | He X.-W.,South China University of Technology
Modern Food Science and Technology | Year: 2013

In order to prepare the polyclonal antibody against Salbutamol (SAL), SAL derivatives were prepared by four kinds of reactions, then they were coupled to BSA and OVA, synthesizing complete antigen. The protein concentration was determined by Ultraviolet spectrophotography and the coupling ratios of four immunogens were calculated. New Zealand white rabbits were immunized by four immunogens to develop anti-SAL antibodies. All the antibodies and coating antigenes were screened and then selected the best combination. The polyclonal antiserum was purified by caprylic acid-ammonium sulfate precipitation. Antibody titer and specificity were analyzed by indirect ELISA. It turned out that the study successfully got the coupling of the SAL complete antigen and the coupling ratios of four immunogens were 9:1, 6:1, 6:1, 12:1, respectively. The optimal antibody-coated antigen combination was obtained and antibody titer was 1:64000. The antibody showed high cross-reactivity with clenbuterol (144%) and terbutaline (169%), without notable cross-reactivity with other structural analogues of SAL. This study lays the foundation for the establishment of Salbutamol, Clenbuterol and Terbutaline multi-residue enzyme-linked immunosorbent assay.


Yang Y.-X.,South China University of Technology | Li M.,South China University of Technology | Li W.-M.,Wondfo Biotech Co. | He X.-W.,South China University of Technology
Modern Food Science and Technology | Year: 2013

Using of 4 Furazolidone Metabolite Residues, immunogen and coating antigen were synthesized. Then, 4 immunogen were used to immunize 2 New Zealand rabbits. 8 antiserums were obtained and purified. Using indirect ELISA method, the OD value which was higher than that of negative samples of serum were filtered out and used in subsequent experiments, and then antibody titer were determined. The results implied when coating antigen A and B coated microtiter plates. No.7 and No.8 antiserums had a good affinity on the coating antigen. The derivatives of Furazolidone Metabolite had a good effect on antibody inhibition. Through the determination of antibody titer, No.7 and No.8 antiserums both had high titer and high specificity features, of which NO.8 antiserum provided higher antibody titer and higher affinity. Through further screening of 2 coating antigen and 2 antiserums, coating antigen B and No.8 antiserum were chosed for ELISE method.


Yu S.-M.,South China University of Technology | Peng Y.-P.,South China University of Technology | Peng Y.-P.,Wondfo Biotech Co. | Yu S.-J.,South China University of Technology | And 2 more authors.
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2012

Latex-antibody complexes were prepared by the method of covalent coupling and the properties of the complexes were studied by fluorescence spectrophotometric method for the purpose of revealing the interaction between latex microspheres and antibody proteins. Analysis of intrinsic fluorescence spectra showed that after being coupled with latex microspheres, the emission maximum of antibody protein showed an obvious blue shift, the intensity of emission maximum decreased significantly, the tertiary structure of antibody protein changed to some extent, the interaction between latex microspheres and antibody proteins had a great quenching effect on the intrinsic fluorescence spectra of antibody proteins, the quenching effect was enhanced along with the increasing pH value and latex concentration, and the quenching mechanism was static quenching. Results of exogenous fluorescence spectra showed that the fluorescence intensity of emission maximum was enhanced significantly after being coupled with latex microspheres, the hydrophobicity of antibody protein was decreasing with the increase in the pH values, however, due to the increasing latex concentration, the hydrophobicity antibody protein was increasing.


Li J.-Y.,South China University of Technology | He X.-W.,South China University of Technology | Li M.,South China University of Technology | Liu X.-Y.,Wondfo Biotech Co. | And 2 more authors.
Modern Food Science and Technology | Year: 2014

The furazolidone metabolite 3-amino-2-oxazolidinone (AOZ) was synthesized at a high yield from the raw materials dimethyl carbonate and ethanol hydrazine hydrate using a catalyst and tetrahydrofuran as a solvent. The results showed that the optimum reaction conditions for maximum AOZ yield (82.7%) were as follows: catalyst dosage, 12%; reaction temperature, 75 ℃; and reaction time, 3 h. Subsequently, a hapten derivative was obtained from the structural transformation of AOZ. Then, immunogens and coating antigens were successfully prepared using a method involving glutaraldehyde to conjugate AOZ and its hapten derivative with activated ovalbumin (cOVA) and bovine serum albumin (cBSA). The hapten and immunogen were identified by gas chromatography-mass spectrometry (GC-MS), elemental analysis, and UV spectrophotometry. The GC-MS data demonstrated the successful preparation of AOZ. The elemental analysis indicated successful formation of the hapten. UV spectrophotometry results showed that conjugation of the hapten with cOVA and cBSA was successful, and the conjugation ratios of immunogen I and immunogen II were 16.74 and 24.05, respectively. ©, 2014, South China University of Technology. All right reserved.

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