Lateral flow biosensor for DNA extraction-free detection of salmonella based on aptamer mediated strand displacement amplification

• The gold-nanoparticle based lateral flow biosensor is extremely simple to use and enables visual detection.
• The tedious cell lysis and DNA/RNA extraction was avoided, while a high sensitivity (101 CFU/mL) was achieved.
• The specificity of the present assay is relative higher than that of nucleic acid based method. It has better response to the viable pathogens in the sample.

Convenient and sensitive point-of-care rapid diagnostic tests for food-borne pathogens have been a long-felt need of clinicians. Traditional approaches such as culture-based methods have good sensitivity and specificity, but they tend to be tedious and time-consuming. Herein we present a simple and sensitive aptamer based biosensor for rapid detection of Salmonella enteritidis (S. enteritidis). One of the aptamers specific for the outmembrane of S. enteritidis was used for magnetic bead enrichments. Another aptamer against S. enteritidis was used as a reporter for this pathogen, which was amplified by isothermal strand displacement amplification (SDA) and further detected by a lateral flow biosensor. As low as 101 colony forming unit (CFU) of S. enteritidis was detected in this study. Without DNA extraction, the reduced handling and simpler equipment requirement render this assay a simple and rapid alternative to conventional methods.