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 × 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 × 102 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. [Display omitted] •The catalytic activity of SNCNCs is discovered.•SNCNCs coupling with ISAR is applied to detection for the first time.•The genosensor can detect live bacteria without preprocessing (3.8 ×102 CFU mL-1).•The genosensor shows excellent specificity and sensitivity in contaminated milk.