A sensitive gold nanoparticle-based lateral flow immunoassay for quantitative on-site detection of Salmonella in foods

Abstract

Salmonella contamination is a leading cause of foodborne infection outbreaks worldwide. Therefore, detecting this bacterium is crucial for public health. Conventional detection methods, while specific and sensitive, are costly, time-consuming, labor-intensive, and require skilled analysts, impacting various industries, particularly the food supply chain. Lateral Flow Immunoassays (LFA) present a promising solution to address the need for a fast, user-friendly, sensitive, and specific detection method. This method overcomes various challenges by providing quick results and being easy to handle, cost-effective, and portable. This study aimed at developing a gold nanoparticle-based lateral flow immunoassay for Salmonella detection in food. Gold nanoparticles coated with anti-Salmonella polyclonal antibodies were characterized using UV–Vis, Raman, and Fourier-transform infrared spectroscopy, in addition to dynamic light scattering, X-ray diffraction, and transmission electron microscopy. Sandwich-type lateral flow immunoassay strips were then constructed and the test optimized for factors like optical density, antibody concentration in the detection zone, incubation time, blocking solutions, and result reading time. The test's selectivity was confirmed by examining its efficiency in detecting Escherichia coli and Staphylococcus aureus, while specificity was assessed against different Salmonella serovars. The developed biosensor displayed superior selectivity, specificity, and sensitivity compared to existing commercial tests. It had a detection limit of 103 CFU·mL−1, providing results in just 15 min after inserting the strip into the sample. Moreover, it successfully detected the presence of Salmonella in contaminated chicken, black pepper, milk, chocolate, and egg samples. This device offers a promising alternative for screening Salmonella in food, potentially enhancing food safety.