Electrochemiluminescence recovery-based aptasensor for sensitive Ochratoxin A detection via exonuclease-catalyzed target recycling amplification

Based on the recovery of the quantum dot (QD) electrochemiluminescence (ECL) and exonuclease-catalyzed target recycling amplification, the development of a highly sensitive aptasensor for Ochratoxin A (OTA) detection is described. The duplex DNA probes containing the biotin-modified aptamer are immobilized on a CdTe QD composite film-coated electrode. The presence of the OTA target leads to effective removal of the biotin–aptamers from the electrode surface via exonuclease-catalyzed recycling and reuse of OTA, which prevents the attachment of streptavidin–alkaline phosphatase (STV–ALP) through biotin–STV interaction. The electron transfer (ET) from the excited state CdTe QD ([CdTe]⁎) to the electro-oxidized species of the enzymatic product of ALP during the potential scan is thus inhibited and the QD ECL emission is restored for quantitative OTA detection. Due to the exonuclease-catalyzed target recycling amplification, the inhibition effect of ET is significantly enhanced to achieve sensitive detection of OTA down to 0.64 pg mL−1. The proposed method is selective for OTA and can be used to monitor OTA in real red wine samples. Our developed ECL recovery-based aptasensor thus offers great potential for the development of new ECL sensing platforms for various target analytes.