A visual detection method for Salmonella Typhimurium based on aptamer recognition and nanogold labeling

A rapid, specific and visible detection method for Salmonella Typhimurium was developed based on the recognition of aptamers coupled with nanogold labeling and silver signal amplification. Briefly, biotinylated aptamer 1, which was specific to Salmonella Typhimurium, was immobilized onto the surface of microtiter plate-wells modified with streptavidin through the binding of biotin and streptavidin. Then, the target bacteria, Salmonella Typhimurium, and the aptamer 2-gold nanoparticle (aptamer 2-AuNPs) conjugates were incubated in the wells to form sandwich-type aptamer/bacteria/aptamer-AuNPs complexes. Under optimal conditions, the correlation between the concentration of Salmonella Typhimurium and the intensity of the signals was observed to be linear within the range of 10–106 cfu mL−1 (R2 = 0.9913), and the detection limit of the proposed method was observed to be 7 cfu mL−1 This developed method offers the potential for rapid, sensitive and visible detection of Salmonella Typhimurium in samples.