A fluorescent aptasensor for highly sensitive detection of OTA and AFB1 and constructing their logical operations

In this study, a universal fluorescent aptasensor was developed for the sensitive detection of ochratoxin A (OTA) and aflatoxin B1 (AFB1). The design integrated a non-competitive transduction platform with highly efficient RNA-cleaving DNAzymes, forming the core of the sensing system. When OTA or AFB1 is present in the sample, the target mycotoxin specifically recognizes and binds to its corresponding aptamer. The strand displacement reaction is significantly hastened by this binding event, and in response, the DNAzyme is released as a consequence. The activated DNAzyme then triggers an amplified fluorescent signal, enabling quantitative detection of the target. The proposed aptasensor displayed sensitivity with a detection limit of 0.26 nM for AFB1 and 0.17 nM for OTA respectively. Beyond single-target detection, the platform also enabled simple and flexible implementation of logical operations between the two mycotoxins, along with the design of orthogonal experiments for multi-target analysis. Furthermore, specificity tests confirmed that other co-existing mycotoxins had negligible interference on the detection of AFB1 or OTA, verifying the sensor's high selectivity. To assess practical applicability, the aptasensor was utilized for the detection of AFB1 and OTA in actual samples, yielding recoveries of 93 %–101 % in milk and 101 %–107 % in corn flour, demonstrating the sensor's reliability in complex matrices. Collectively, this developed fluorescent aptasensor features portability, simplicity, cost-effectiveness, and broad adaptability, making it a promising alternative tool for detecting various mycotoxins in food safety monitoring and related fields.