An "off-on" electrochemiluminescence biosensor based on CRISPR-Cas12a for ultrasensitive determination of aflatoxin...

Accurate and sensitive determination of aflatoxin B1 (AFB1) is of vital importance for food safety. Herein, an electrochemiluminescence (ECL) "off-on" switch sensor combined with CRISPR-Cas12a is fabricated for the quantitative analysis of AFB1. Initially, the DNA activator is effectively locked by two AFB1 aptamers. Once the target AFB1 is introduced, the activator is released in an open state and thus is recognized by the Cas12a-crRNA duplex. Black hole quencher (BHQ)-marked DNA strands are digested by the activated CRISPR-Cas12a system. Owing to the resonance energy transfer (RET) between aggregation-induced ECL active (AIECL-active) polymer dots (Pdots) and BHQ, the ECL signal of Pdots switches from signal "off" to "on" along with the detachment of BHQ from the electrode surface. The proposed ECL sensor thus achieves sensitive quantification of AFB1 with a detection limit of 0.06 pg mL^-1. This work provides an effective strategy for mycotoxin determination.