Locking-Fluorescence Signals Regulated CRISPR/Cas12a Biosensor Based on Metal–Organic Framework for Sensitive Detection of <i>Salmonella typhimurium</i>

The efficient, sensitive, and rapid detection of <i>Salmonella typhimurium</i> (<i>S. typhimurium</i>) in food and food products is important to ensure food safety and health. This study developed a fluorescence biosensing assay that integrated recombinase-aided amplification (RAA) and CRISPR/Cas12a with a zeolitic imidazolate framework-8@fluorescein sodium (ZIF-8@FLS) nanocomposite for the sensitive detection of <i>S. typhimurium</i>. In this approach, using RAA as a preamplification module, CRISPR/Cas12a-AChE as a target recognition and dual-enzyme cascade amplification module, and the prepared ZIF-8@FLS with high porosity and rapid pH responsiveness as a fluorescence signal explosive amplification module, the RAA-CRISPR/Cas12a-ZIF-8@FLS biosensor was constructed. Under optimal conditions, it exhibited an excellent linear relationship for <i>S. Typhimurium</i>, with a sensitive detection limit as low as 1.3 × 10² CFU/mL and could complete sample detection within 2 h relying on the RAA and ZIF-8@FLS explosive fluorescence rapid response, demonstrating its significant advantages in specificity, sensitivity, and reliability in food-borne pathogens detection.