Hybridization chain reaction-assisted enzyme cascade genosensor for the detection of Listeria monocytogenes

Foodborne diseases caused by pathogens may threaten public health and the social economy. We demonstrated a method for identifying pathogenic Listeria monocytogenes using DNA logic operations. To achieve accurate species distinguishing, three specific sequences of Listeria monocytogenes genomic DNA were screened out and used as the feature sequences. Three complementary probes with tag modification were designed as sensing elements and exert affinity for magnetic beads, glucose oxidase (GOx), and horseradish peroxidase (HRP). To obtain a digital output (YES/NO answer) for rapid determination, a Boolean logic function was employed. Three sensing probes enabled the recognition of the target sequence (input) and the formation of a target DNA/probe hybrid. Through magnetic separation and affinity binding events, the target DNA/probes hybrid led to the construction of GOx/HRP enzyme cascade, which produced a visualized color signal (output) in the presence of substrates, glucose, and 3, 3', 5, 5'-tetramethylbenzidine (TMB). A hybridization chain reaction (HCR) was coupled with this sensing scaffold to increase the binding of the enzyme cascade and amplify the output signal. The logical functional biosensor showed high selectivity of Listeria monocytogenes over other Listeria species. This sensing platform provides a simple, sensitive, and highly specific method for detecting Listeria monocytogenes.