CRISPR/Cas12a empowered electrochemical biosensor for ultrasensitive detection of Vibrio parahaemolyticus in seafood samples.

Rapid and ultrasensitive detection of Vibrio parahaemolyticus (V. parahaemolyticus, Vp) is of great significance for the early prevention of foodborne disease. Traditional methods for detecting Vp are time-consuming, exhibiting low sensitivity and specificity. In this study, CRISPR/Cas12a system is integrated with electrochemical sensing and polymerase chain reaction (PCR) to establish a PCR-based E-CRISPR biosensor for Vp detection. The target DNA extracted from Vp is amplified by PCR, then activate CRISPR/Cas12a system to cleave methylene blue (MB)-labeled hairpin DNA probes on electrode, resulting in great changes in current. The employment of hairpin DNA probes reduces the steric hindrance for Cas12a trans-cleavage, acquiring a better cleavage efficiency and sensing performance. Under optimal conditions, the limit of detection reaches 1.17 copies/μL (genomic DNA), 1.23 CFU/mL (standard bacteria), and 12.3 CFU/g (artificially contaminated shrimp samples) respectively. Moreover, the PCR-based E-CRISPR biosensor demonstrates superior reproducibility and specificity. Most importantly, the E-CRISPR biosensor were in 100 % agreement with real time quantitative PCR for the detection of 18 seafood samples, which confirms the biosensor's broad applicability for monitoring Vp in complex food matrix. Our developed E-CRISPR biosensor demonstrates to be a simple, rapid and ultrasensitive method for Vp detection in the food supply chain, and can be extended to other foodborne pathogens.