A rapid and highly sensitive protocol for the detection of Escherichia coli O157:H7 based on immunochromatography assay combined with the enrichment technique of immunomagnetic nanoparticles
Hui Qi1, Zhen Zhong1, Han-Xin Zhou1, Chun-Yan Deng1, Hai Zhu2, Jin-Feng Li2, Xi-Li Wang2, Fu-Rong Li1,3
1Clinical Medical Research Center, The Second Clinical Medical College (Shenzhen People's Hospital), Jinan University, 2Shenzhen Bioeasy Biotechnologies Co, Ltd, 3Shenzhen Institute of Gerontology, Shenzhen, People's Republic of China
Background: Escherichia coli O157:H7 (E. coli O157:H7) is an important pathogenic bacterium that threatens human health. A rapid, simple, highly sensitive, and specific method for the detection of E. coli O157:H7 is necessary.
Methods: In the present study, immunomagnetic nanoparticles (IMPs) were prepared with nanopure iron as the core, coated with E. coli O157:H7 polyclonal antibodies. These IMPs were used in combination with immunochromatographic assay (ICA) and used to establish highly sensitive and rapid kits (IMPs+ICA) to detect E. coli O157:H7. The kits were then used to detect E. coli O157:H7 in 150 food samples and were compared with conventional ICA to evaluate their efficacy.
Results: The average diameter of IMPs was 56 nm and the amount of adsorbed antibodies was 106.0 µg/mg. The sensitivity of ICA and IMPs+ICA was 105 colony-forming units/mL and 103 CFUs/mL, respectively, for purified E. coli O157:H7 solution. The sensitivity of IMPs+ICA was increased by two orders, and its specificity was similar to ICA.
Conclusion: The kits have the potential to offer important social and economic benefits in the screening, monitoring, and control of food safety.
Keywords: colloidal gold, immunomagnetic nanoparticles, Escherichia coli O157:H7, immunochromatographic assay
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