CRISPR/Cas12a-powered CLASA towards OTA ultrasensitive detection in cereal samples

Abstract

Ochratoxin A (OTA) is classified as a Class 2B carcinogens and poses a significant risk bto the liver, kidney and other organs, potentially leading to carcinogenic and teratogenic effects. Accurate monitoring of OTA content in food is crucial for safeguarding human and animal health. Here, a novel approach called the CRISPR/Cas12a enzyme-linked aptamer-sorbent assay (CLASA) was developed, which integrates the high-performance trans-cleavage ability of CRISPR/Cas12a with the cost-effective and high-affinity properties of aptamer for ultra-sensitive OTA detection. In this strategy, we incubated aptamers on microwell plates, and used the fluorescence intensity changes caused by OTA and crRNA competitively bind OTA-specific aptamer to achieve the quantitative detection. Our sensitive CLASA method not only solves the problems of poor repeatability and relatively low sensitivity of fluorescence based-CRISPR/Cas12a reaction in solution, but also solves the defects of expensive antibody and false positive result in traditional ELISA method, achieving a limit of detection (LOD) as low as 171 fg·mL−1 with a broad linear range from 1 pg·mL−1 to 1000 pg·mL−1. The presented CLASA approach was validated successfully by using commercial ELISA kit on rice and oat samples as well. Furthermore, by strategically modifying the sequences of aptamer and crRNA, our CLASA platform can be flexibly customized to detect a wide range of small molecular targets. This adaptability allows for the extension of our framework beyond nucleic acid substances, enabling the detection of non-nucleic acid compounds using the CRISPR-Cas12a system. As a result, our CLASA approach holds great promise as a versatile sensing kit with applications in various fields requiring sensitive and specific detection of diverse analytes.