A Label-Free ECL Sensing Platform for Sensitive Detection of OTA Based on Target-Regulated Activation of CRISPR-Cas12a

Ochratoxin A (OTA) is a terrible mycotoxin, which causes environmental problems and seriously endangers people's food safety. The development of the biosensor for OTA is be imperative. Here, taking advantage of CRISPR-Cas12a, a member of CRISPR-Cas family, as the amplification tool, a label-free ECL sensing platform for the detection of OTA is developed. A well-designed crRNA hybridized with its complementary strand (also as aptamer for OTA), and activated the activity of Cas12a (Activated stage). While in the existence of OTA, crRNA and its complementary strand dissociated due to the competitive effect of OTA, which inhibited the activity of Cas12a (Locked stage). Inert Cas12a could not digest hairpin DNA on the electrode, which declined ECL intensity because of steric hindrance. As a consequence, this ECL sensing platform can realize to assay OTA in the drinks.