Abstract
Escherichia coli O157:H7 is regarded as one of the most harmful pathogenic microorganisms related to foodborne diseases. This paper proposes a rapid-detection biosensor for the sensitive and quantitative analysis of E. coli O157:H7 in biological samples by surface-enhanced Raman scattering (SERS)-based lateral flow immunoassay (LFIA). A novel gold-shell silica-core (SiO2/Au) nanosphere (NP) with monodispersity, good stability, and excellent SERS activity was utilized to prepare high-performance tags for the SERS-based LFIA system. The SiO2/Au SERS tags, which were modified with two layers of Raman reporter molecules and monoclonal antibodies, effectively bind with E. coli O157:H7 and form sandwich immune complexes on the test lines. E. coli O157:H7 was quantitatively detected easily by detecting the Raman intensity of the test lines. Under optimal conditions, the limit of detection (LOD) of the SiO2/Au-based SERS-LIFA strips for the target bacteria was 50 cells/mL in PBS solution, indicating these strips are 2,000 times more sensitive than colloidal Au-based LFIA strips. Moreover, the proposed assay demonstrated high applicability in E. coli O157:H7 detection in biological samples, including tap water, milk, human urine, lettuce extract and beef, with a low LOD of 100 cells/mL. Results indicate that the proposed SERS-based LFIA strip is applicable for the sensitive and quantitative determination of E. coli O157:H7.
Highlights
As one of the major foodborne pathogens that cause food poisoning and serious illnesses worldwide, Escherichia coli O157:H7 is a significant threat to public health (Suaifan et al, 2017; Hassan et al, 2019)
The products synthesized at different stages were analyzed via Transmission electron microscope (TEM) and Scanning electron microscope (SEM) to characterize their structure and morphology
After the SiO2 NPs were coated with PEI layer, the 3–5 nm Au/dithiobis-(2-nitrobenzoic acid) (DTNB) NPs densely adhered on the surface of the SiO2/PEI NPs (Figure 1B)
Summary
As one of the major foodborne pathogens that cause food poisoning and serious illnesses worldwide, Escherichia coli O157:H7 is a significant threat to public health (Suaifan et al, 2017; Hassan et al, 2019). E. coli O157:H7 Detection Using Dual DTNB-Modified SiO2/Au-Based SERS-LFIA Strips
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