CRISPR-Based Paper Test Using Cas12a for Two-Way Detection of Disease-Causing DNA

Detection of as few as 40 full genomic copies of three major bacterial pathogens was achieved using a novel optical biosensing platform.

• The platform utilizes cost-efficient and scalable paper support for pathogen detection.
• Fluorescent DNA-templated silver nanoclusters and a CRISPR-Cas12a cascade reaction are employed for identifying pathogens.
• Each sensor is designed as a letter-shaped paper cutout corresponding to a specific pathogen: 'C' for Campylobacter jejuni, 'E' for Shiga toxin-producing Escherichia coli, and 'L' for Listeria monocytogenes.
• Detection is facilitated through an ON-to-OFF mechanism, where target recognition results in fluorescence loss.
• A two-step CRISPR-Cas12a reaction enhances the clarity of detection by providing an ON signal when the target is present and an OFF signal when it is absent.
• The platform successfully detects individual and multiple pathogens in all possible seven combinations.

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