Dramatically Enhanced Immunochromatographic Assay Using Cascade Signal Amplification for Ultrasensitive Detection of Escherichia coli O157:H7 in Milk.
J Agric Food Chem
; 68(4): 1118-1125, 2020 Jan 29.
Article
em En
| MEDLINE
| ID: mdl-31895982
ABSTRACT
The conventional colloidal gold immunochromatographic assay (AuNP-ICA) cannot meet the requirements for the rapid and sensitive detection of Escherichia coli (E. coli) O157H7 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 O157H7 detection and had a detection limit of 1.25 × 101 CFU/mL, which is approximately 400-fold lower than that of traditional AuNP-ICA (5 × 103 CFU/mL). The amplified strip had no background signal in the T-line zone in the absence of E. coli O157H7 even after one round of cascade signal amplification. The enhanced strip demonstrated excellent selectivity against E. coli O157H7 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 O157H7. 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 O157H7 cell in a 75 µL solution.
Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Imunoensaio
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Escherichia coli O157
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Leite
Tipo de estudo:
Diagnostic_studies
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Evaluation_studies
Limite:
Animals
Idioma:
En
Revista:
J Agric Food Chem
Ano de publicação:
2020
Tipo de documento:
Article