Impedimetric DNA Aptasensor for Sensitive Detection of Ochratoxin A in Food

Abstract

Abstract We report a high sensitive biosensor based on DNA aptamers for detection of ochratoxin A (OTA). The thiolated DNA aptamers specific to OTA of different configurations have been immobilized by chemisorption to the surface of a gold electrode. Electrochemical impedance spectroscopy (EIS) in the presence of a redox probe [Fe(CN) 6 ] −3/−4 has been used for the determination of the charge transfer resistance, R ct , followed by addition of OTA. The R ct increased with increasing OTA concentration in the range of 0.1–100 nM. The limit of detection (0.12–0.40 nM) depended on the configuration of the aptamers. The sensor was regenerable and validated in food samples with satisfactory recovery.