Development of rapid gold nanoparticles based lateral flow assays for simultaneous detection ofShigellaandSalmonellagenera

SalmonellaandShigellagenera are common pathogens that contaminate foods and beverages. Lateral flow assays (LFA) are commonly used to detect these pathogens. However, most of the developed LFAs are for single detection. Simultaneous detection of pathogens is required to reduce cost and time. In this work, 40 nm gold nanoparticles (AuNPs) were synthesized using the seeding growth method as labeling agent. The AuNPs were characterized and conjugated with mouse anti-Gram negative endotoxin antibody. The nitrocellulose membrane HF135 was immobilized with anti-mouse IgG antibody as a control line and two separate test lines with either anti-Shigellaor anti-Salmonellaantibody, respectively. Color intensity of test lines was observed for positive samples. A milk sample was used as proof of concept to mimic actual contamination. The limit of detection of the LFA was 3.0 x 10(6)CFU/mL for multiplex detection ofShigella flexneriandSalmonellaTyphi and for both single detections. The result was comparable with the enzyme-linked immunosorbent assay (ELISA) analysis. The produced LFA could differentiate betweenShigella flexneri,Shigella boydii,SalmonellaEnteritidis, andSalmonellaTyphi. The developed LFA was able to identifyShigella flexneriandSalmonellaTyphi with good sensitivity in milk samples, thus, beneficial to ensure the safety of food before entering the market.