A Versatile CRISPR/Cas12a Autocatalytic Cascade System via Structure-Switching V-Type Split Probe for Highly Sensitive DNA Diagnostics

The rapid detection of pathogen nucleic acids is critical for controlling infectious disease outbreaks and providing timely treatment. However, current molecular diagnostic applications, including sensitive CRISPR/Cas-based detection systems, rely on target preamplification, which often requires expensive equipment and strict adherence to sometimes complex workflows. Here, we describe a rapid, simple, and amplification-free CRISPR/Cas-based diagnostic system that employs a structure-switching V-shaped DNA probe with a Cas12a recognition sequence split by an ssDNA loop to establish a positive feedback loop and a signal amplification cascade. This approach exhibited an ultralow background signal, rapid production of an exponential signal, and atto-molar sensitivity. It was incorporated into microfluidic and lateral flow assay applications for multiplex detection of distinct papillomavirus strains and point-of-care detection of monkeypox virus infections, respectively. The approach thus has significant potential for rapid and sensitive detection of specific pathogen-derived DNA targets in both clinical laboratory and point-of-care applications.