Immunochromatographic assay for the point-of-care diagnosis of food borne Salmonella strains using smartphone application

Abstract

Salmonella strain is a prevalent pathogen, affecting poultry industry and hence human population around the world. Host-specific pathogen infections including fowl typhoid, pullorum disease and typhoid fever affects poultry birds, causing huge economic loss worldwide. This study explored the fabrication of immunochromatographic (ICG) strip by colorimetric method integrated with smartphone ColorGrab application for the detection of Salmonella using in-house generated antibodies (Abs) conjugated with gold nanoparticles. The developed point-of-care diagnostic platform was fabricated in-house and tested to detect the presence of Salmonella in a linear range of 10⁷-10⁰ CFU/mL with the limit of detection (LOD) of 10³, 10² and 10⁴ CFU/mL respectively, for Salmonella gallinarum (S.gal), Salmonella pullorum (S.pul) and Salmonella enteritidis (S.ent), which was further confirmed by smartphone-based ColorGrab application. The fabricated ICG strips were further validated using spiked fecal, meat, and milk samples which provided results in 10 mins with stability at 4 °C and 37 °C up to 28 days. Hence, the fabricated in-house ICG strip can be used as a portable, cost-effective diagnostic device for rapid detection of Salmonella strains in food samples.

Keywords: Colorimetric; Gold nanoparticles; Immunochromatographic strip; Point-of-care; Salmonella.