Analytical Sciences

An Electrochemical Sensor Based on Structure Switching of Dithiol-modified Aptamer for Simple Detection of Ochratoxin A

Donny Nugraha MAZAAFRIANTO,*1 Akihiko ISHIDA,*2 Masatoshi MAEKI,*2 Hirofumi TANI,*2 and Manabu TOKESHI*2,*3,*4,*5

*1 Graduate School of Chemical Sciences and Engineering, Hokkaido University, Japan
*2 Division of Applied Chemistry, Faculty of Engineering, Hokkaido University, Japan
*3 ImPACT Research Center for Advanced Nanobiodevices, Nagoya University, Japan
*4 Innovative Research Center for Preventive Medical Engineering, Nagoya University, Japan
*5 Institute of Innovation for Future Society, Nagoya University, Japan

In this study, we developed an electrochemical sensor for ochratoxin A (OTA) by using an aptamer having a dithiol-based anchor, which exhibited higher stability on a gold electrode than a monothiol-based aptamer because of its two anchors. The sensor was also based on a signal-on scheme that produces a signal current resulting from structure-switching of the aptamer upon interaction with OTA. For simple fabrication of this sensor, the non-covalent interaction of methylene blue with the aptamer was also employed as an electrochemical indicator. In this study, the performance of the sensor, including the dissociation constant of the aptamer–OTA complex, was characterized. The proposed sensor exhibited high reproducibility and enough sensitivity to detect the minimum amount of OTA required for the analysis of real food samples with a limit of detection of 113 pM.

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