Journal
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
Volume 68, Issue 4, Pages 1118-1125Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.jafc.9b07076
Keywords
immunochromatographic assay; cascade signal amplification; in situ gold growth; nanozyme-mediated catalytic deposition; Escherichia coli O157:H7
Funding
- National Key Research and Development Program of China [2018YFC1602202]
- Opening Fund of Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology [028074911709]
- National Natural Science Foundation of China [31801766, 31760485]
- Ministry of Science and Technology of the People Republic of China [2016YFD0200803-3]
- Interdisciplinary Innovation Fund of Natural Science, Nanchang University [916627060003-ZD01]
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The conventional colloidal gold immunochromatographic assay (AuNP-ICA) cannot meet the requirements for the rapid and sensitive detection of Escherichia coli (E. coli) O157:H7 because of its poor sensitivity. Herein, a novel two-step cascade signal amplification strategy that integrates in situ gold growth and nanozyme-mediated catalytic deposition was proposed to enhance the detection sensitivity of conventional AuNP-ICA dramatically. The enhanced strip displayed ultrahigh sensitivity in E. coli O157:H7 detection and had a detection limit of 1.25 x 10(1) CFU/mL, which is approximately 400-fold lower than that of traditional AuNP-ICA (5 x 10(3) CFU/mL). The amplified strip had no background signal in the T-line zone in the absence of E. coli O157:H7 even after one round of cascade signal amplification. The enhanced strip demonstrated excellent selectivity against E. coli O157:H7 with a negligible cross-reaction to nine other common pathogens. Intra-assays and interassays showed that the improved strip has acceptable accuracy and precision for determining E. coli O157:H7. The average recoveries in a real milk sample ranged from 87.33 to 112.15%, and the coefficients of variation were less than 10%. The enhanced strip also showed great potential in detecting a single E. coli O157:H7 cell in a 75 pL solution.
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