An electrochemical aptasensor based on exonuclease III-assisted signal amplification coupled with CRISPR-Cas12a for ochratoxin A detection

Selective and sensitive determination of ochratoxin A (OTA) is critical due to its high toxicity and wide distribution. Here, a neoteric electrochemical biosensor based on an exonuclease III (Exo III)-assisted recycling reaction triggering the trans-cleavage ability of CRISPR-Cas12a was developed, allowing the specific and ultrasensitive detection of OTA. In this strategy, the Exo III-assisted recycling reaction was used to convert and magnify the target recognition affair into the trigger DNA chain to the trans-cleavage activity of Cas12a for detecting electrochemical signal changes, thus enhancing detection sensitivity. When the Fc-ssDNA was fixed onto a glassy carbon electrode and used as a reporter probe under optimized conditions, the method showed good selectivity and sensitivity for OTA determination, and a detection limit of 0.74 fg/mL. Furthermore, the established method could sensitively identify OTA in spiked rice and peanut samples, demonstrating its application potential for practical detection.