A label-free AuNP bioprobe-assisted CRISPR/Cas12a colorimetric platform for high-throughput detection of Staphylococcus aureus ST398

Rapid and accurate screening of foodborne pathogens in contaminated food is with great significance for food safety. AuNPs-based colorimetric assay is an attractive strategy in the field of food safety inspection, but is limited by tedious probe preparation, low color rendering resolution, and narrow color gamut. Herein, we proposed an enhanced colorimetric platform based on the CRISPR/Cas12a system and label-free DNA-AuNP probe (CDP-ECP) for high-throughput detection of Staphylococcus aureus ST398. In this strategy, a novel and specific gene targeting S. aureus ST398 was identified and efficient AuNP-bioprobe was successfully prepared. Through a PCR/RAA amplification, the trans-ssDNA cleavage ability induced by target DNA product triggered an aggregation performance for the prepared AuNP-bioprobe pairs, which could realize target colorimetric detection within 50 min. Under optimal conditions, the colorimetric assay could detect as low as 6.4 × 102 cfu/mL of S. aureus ST398 in pure culture. Specific gene mining and target-induced trans-cleavage character gave this method a superior specificity and anti-interference. More importantly, this colorimetric method can be extended to a high-throughput platform for rapid detection of spiked and natural sample by using a common microplate reader. Since it is simple to operate, low cost, high sensitivity and specificity, this new platform is fully qualified for clinical diagnosis, environmental monitoring onsite testing requirements.