A genosensor platform based on DNA biofunctionalized SNCNCs coupled with IS-primer amplification reaction for sensitive and rapid Listeria monocytogenes detection

Accurate and timely diagnosis of Listeria monocytogenes (L. monocytogenes), a well-known foodborne pathogen with a serious threat to human life and health, is critical for managing bacterial infections and food quality. Here, we report a genosensor platform based on DNA biofunctionalized superparamagnetic nickel colloidal nanocrystal clusters (SNCNCs) coupling with IS-primer amplification reaction (ISAR) for rapid, ultrasensitive and specific L. monocytogenes detection. Specifically, the catalytic activity of SNCNCs was identified. After three-step modification, the signal unit was formed by immobilizing AuNPs and hairpin probes on the surface of SNCNCs, achieving enhanced catalytic activity, leading to the reduction of a colorimetric substrate 4-nitrophenol (4-NP). The in-situ signal amplification of target RNA on the surface of SNCNCs coupling with ISAR showed high sensitivity and a detection limit of 1.50 x 10(-3) ng mL(-1) under optimized conditions. As SNCNCs can bind and lyse bacteria, this genosensor can detect live L. monocytogenes without RNA extraction, with a detection limit of 3.80 x 10(2) CFU mL(-1). Furthermore, the system could also detect L. monocytogenes in artificially contaminated milk samples within 6 h. These results indicate the great potential of our method for sensitive, specific, convenient and low-cost bacterial detection in food, environment and clinics.

Automated summary

In this study, a genosensor platform based on DNA biofunctionalized superparamagnetic nickel colloidal nanocrystal clusters (SNCNCs) coupled with IS-primer amplification reaction (ISAR) was developed for rapid, ultrasensitive, and specific detection of Listeria monocytogenes (L. monocytogenes). The method showed high sensitivity, good specificity, convenience, and low cost, making it a promising tool for bacterial detection in food, environment, and clinics.