Rapid and sensitive detection of E. coli O157:H7 by lateral flow immunoassay and silver enhancement

Abstract

The aim of this study was to develop a sensitive lateral flow immunoassay (LFIA) for the rapid detection of Escherichia coli (E. coli) O157:H7, a pathogen contributor to diseases and fatalities worldwide. Au nanoparticles with high stability, uniform size, and shape were synthesized and coated with heterobifunctional PEG polymer with carboxyl groups, and they were bioconjugated to be used as label in sandwich-LFIA. Then, a silver enhancement strategy was developed as an accessible, rapid, and cost-effective approach for signal amplification to reduce the limit of detection (LOD). The optimal results were achieved when a solution of silver nitrate and hydroquinone/citrate buffer was added to the strips for 4 min. This led to a decrease in the visual LOD from 2 × 106 (CFU mL−1) to 2 × 103 (CFU mL−1), resulting in a threefold improvement in sensitivity compared to the conventional LFIA system. The specificity of the system was evaluated by using non-target bacteria (E. coli BL21 and E. coli T515) and its reliability was determined by testing commercial food samples (milk, tap water, and orange juice), demonstrating its effectiveness for quickly detecting pathogenic bacteria in food products. Graphical Abstract

“First alert” for Drinking Water Quality: Commercial Water Quality Testing Kits for Community-Engaged Research

“…The development of immunoassays for a wide range of parameters within the sensitivity range of MCLs for drinking water will enhance the performance of tests in CEnR. For instance, these assay types are in development for E. coli 63,64 and copper. 65 Easy interpretation with a yes or no option will be particularly valuable, addressing the challenges associated with result interpretation within the community.…”

“…For instance, these assay types are in development for E. coli , and copper . Easy interpretation with a yes or no option will be particularly valuable, addressing the challenges associated with result interpretation within the community.…”

Post-Assay Chemical Enhancement for Highly Sensitive Lateral Flow Immunoassays: A Critical Review

“…Enlarged Au@Ag nanoparticles have black/dark grey coloration and can be easily detected on the white background of the nitrocellulose membrane ( Figure 4 c). Silver enhancement is actively used for the post-assay signal enhancement of various analytes, e.g., viruses [ 78 , 79 ], pathogenic bacteria cells [ 80 , 81 ], xenobiotics in food [ 82 , 83 , 84 ], and high molecular [ 85 ] and small molecular weight biomarkers [ 86 ].…”

“…Enlarged Au@Ag nanoparticles have black/dark grey coloration and can be easily detected on the white background of the nitrocellulose membrane (Figure 4c). Silver enhancement is actively used for the post-assay signal enhancement of various analytes, e.g., viruses [78,79], pathogenic bacteria cells [80,81], xenobiotics in food [82][83][84], and high molecular [85] and small molecular weight biomarkers [86]. actively used for the post-assay signal enhancement of various analytes, e.g., viruses [78,79], pathogenic bacteria cells [80,81], xenobiotics in food [82][83][84], and high molecular [85] and small molecular weight biomarkers [86].…”

“…Silver enhancement is actively used for the post-assay signal enhancement of various analytes, e.g., viruses [78,79], pathogenic bacteria cells [80,81], xenobiotics in food [82][83][84], and high molecular [85] and small molecular weight biomarkers [86]. actively used for the post-assay signal enhancement of various analytes, e.g., viruses [78,79], pathogenic bacteria cells [80,81], xenobiotics in food [82][83][84], and high molecular [85] and small molecular weight biomarkers [86]. On the one hand, the low stability of silver enhancement components is a drawback for POC application.…”