Aptamer-DNAzyme hairpins for biosensing of Ochratoxin A

We report an aptasensor for biosensing of Ochratoxin A (OTA) using aptamer-DNAzyme hairpin as biorecognition element. The structure of this engineered nucleic acid includes the horseradish peroxidase (HRP)-mimicking DNAzyme and the OTA specific aptamer sequences. A blocking tail captures a part of these sequences in the stem region of the hairpin. In the presence of OTA, the hairpin is opened due to the formation of the aptamer–analyte complex. As a result, self-assembly of the active HRP-mimicking DNAzyme occurs. The activity of this DNAzyme is linearly correlated with OTA concentration up to 10 nM, showing a limit of detection of 2.5 nM.

► Ochratoxin A, a possible human carcinogen from the mycotoxins group, was detected.
► An aptamer-DNAzyme (HRP-mimicking) hairpin was designed as bio-recognition element.
► The DNAzyme activity depends on the hairpin opening due to the OTA–aptamer complex.
► The achieved LOD (2.5 nM) is suitable for OTA detection in different food samples.
► This simple assay is a rapid (1 h for 96 samples) and cost-effective protocol.