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Xie Q.-Y.,Nanchang University | Wu Y.-H.,Nanchang University | Wu Y.-H.,Jiangxi Zodolabs Bioengineering Co | Xiong Q.-R.,Nanchang University | And 6 more authors.
Biosensors and Bioelectronics | Year: 2014

Label selection is of vital importance for immunochromatographic assays. In this study, the fluorescent microsphere test strip and colloidal gold immunochromatographic test strip (FM-ICTS and CG-ICTS) were developed for the detection of Escherichia coli O157:H7 on the basis of the sandwich format. Two types of labels, namely, colloidal gold particles (CG) and carboxyl-modified fluorescent microspheres (FMs), were compared while coupling with anti-E. coli O157:H7 monoclonal antibody (mAb). The FM-ICTS and CG-ICTS were also compared. Results show that the coupling rate between FMs and mAb was higher than that between CG and mAb. Under optimum conditions, the sensitivity of FM-ICTS was eight times higher than that of CG-ICTS. Approximately 0.1μg of mAb was used in every FM-ICTS, whereas 0.4μg of mAb was used in every CG-ICTS. The coefficient of variation of FM-ICTS and CG-ICTS was 4.8% and 16.7%, respectively. The FM-ICTS and CG-ICTS can be stored at room temperature for 12 months and specific to five E. coli O157:H7 strains. Milk sample inoculated with E. coli O157:H7 were tested by the FM-ICTS and CG-ICTS. The FM-ICTS sensitivity was 104CFU/ml while the CG-ICTS sensitivity was 105CFU/ml. The sensitivity, consumption of antibodies, and coefficient of variation of FM-ICTS were better than those of CG-ICTS for the detection of E. coli O157:H7. © 2013 Elsevier B.V.

Peng T.,Nanchang University | Yang W.-C.,Jiangxi Zodolabs Bioengineering Co | Lai W.-H.,Nanchang University | Xiong Y.-H.,Nanchang University | And 2 more authors.
Analytical Methods | Year: 2014

Clenbuterol is banned as a feed additive in China and in other countries. Lateral-flow immunochromatographic assay can be applied in the quantitative detection of clenbuterol. Our group has previously developed an immunochromatographic assay to detect clenbuterol in swine urine rapidly and quantitatively. This method was based on the ratio of the color intensity of a test line to that of a control line (T/C) to offset the matrix effects of samples and diminish variations among different strips. In this study, the stability of this method was successfully improved and verified by an accelerated aging test that involved storage at 60 °C for three weeks. Results showed that the control line was the main factor affecting the strip stability. To improve the stability of the test strip, we mixed the goat anti-mouse antibody spotted on the control line with WellChampion, Antibody Enhancer, and Protein StabilPLUS. Alterations in the T/C ratio were evaluated using negative and positive swine urine samples. Stability was effectively improved by adding WellChampion. Furthermore, the newly prepared strips showed satisfactory stability by drying the nitrocellulose membrane at 60 °C for one day. © the Partner Organisations 2014.

Liu D.,Nanchang University | Huang Y.,Nanchang University | Wang S.,Nanchang University | Liu K.,Nanchang University | And 4 more authors.
Food Control | Year: 2015

A modified lateral flow immunoassay (two-step assay) was developed to detect trace aflatoxin M1 (AFM1) in raw milk. In contrast to conventional LFIA, two kinds of immunomagnetic nanobeads (IMNBs) were used. One IMNB with high antibody concentration was used to capture AFM1 in the test sample, whereas the other IMNB with low antibody concentration was used to elucidate the results of the test. Critical factors, such as antibody concentration of IMNBs and size of IMNBs, were investigated. The two-step assay exhibited an ideal sensitivity to screen trace AFM1 in milk samples without extra sample pretreatment. The cutoff value of the naked eye was 0.02μg/L and satisfied the European Union's maximum limit of AFM1 in raw milk, heat-treated milk, and milk used to manufacture milk-based products and even in baby foods. With the same antibody, sensitivity was enhanced approximately 25 and 50 times when compared with conventional IMNB-based LFIA and gold-based LFIA, respectively. Corresponding results of 13 raw milk samples were obtained between this two-step assay and referenced enzyme-linked immunosorbent assay. © 2014 Elsevier Ltd.

Peng T.,Nanchang University | Zhang F.S.,Jiangxi Agricultural Product Quality Safety and Inspection Center | Yang W.C.,Jiangxi Zodolabs Bioengineering Co | Li D.X.,Jiangxi Agricultural Product Quality Safety and Inspection Center | And 4 more authors.
Journal of Food Protection | Year: 2014

Clorprenaline (CLP), a β2-adrenergic agonist, was first found in veterinary drugs for cold treatment in China in 2013. It is a potential new lean meat-boosting feed additive because it can promote animal muscular mass growth and decrease fat accumulation. A competitive colloidal gold-based lateral flow immunoassay system with a portable strip reader was successfully developed for rapid quantitative detection of CLP residue in swine urine. The detection system was optimized so that the detection can be completed within 9 min with a limit of detection of 0.15 β2. The assay exhibited good linear range from 3.0 to 20.0 β2, with reliable correlation of 0.9970 and with no obvious cross-reaction with five other β2-agonist compounds. Twenty spiked swine urine samples were tested by lateral flow immunoassay and liquid chromatography-tandem mass spectrometry to confirm the accuracy of the system. Results show good correlation between the two methods. This method is rapid, sensitive, specific, and convenient. It can be applied in the field for on-site detection of CLP in urine samples. Copyright © 2014, International Association for Food Protection.

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