A self-calibrated electrochemical aptasensor based on DNA-mediated Au/PB NFs and Pt/ZnCo MOF for the detection of OTA.

Abstract

A self-calibrated ratiometric electrochemical aptasensor was developed for the detection of ochratoxin A. This sensor is based on DNA-mediated gold/prussian blue nanoflowers (Au/PB NFs), methylene blue/platinum/zinc-cobalt metal-organic framework (MB/Pt/ZnCo MOF), and an exonuclease III (Exo III)-driven bipedal DNA walker cyclic amplification strategy. The self-calibration mechanism of this sensor relies on the ratio between the response signal of MB/Pt/ZnCo MOF (IMB) and the internal reference signal of Au/PB NFs (IPB). This ratio can effectively resist external interference factors. DNA-mediated Au/PB NFs with a flower-like structure provide stable internal reference signals and promote electron transfer. MB/Pt/ZnCo MOF, leveraging ZnCo MOF with a porous structure and bimetallic synergistic effects, and Pt with electrocatalytic activity, serve as response signals. An Exo III-driven biped DNA walker was used to realize the cyclic amplification strategy. The sensor showed a wide linear range of 0.001~500 ng/mL, with a low limit of detection of 0.17 pg/mL. The detection capability of spiked corn flour, wine, and coffee powder samples was satisfactory, and the detection results for the quality control samples of coarse rice flour and wheat flour were not significantly different from those of high-performance liquid chromatography (HPLC), showing the potential for practical application.