▎ 摘　　要

Okadaic acid (OA), which is one of the representative diarrhetic shellfish poisonings, is a prevalent food-poisoning toxin in the world. As OA consumption induces various digestive diseases, a strict monitoring tool for OA is highly required. In this study, we demonstrate the development of an aptamer-based fluorometric OA sensor. First, the affinity of the aptamer towards OA was confirmed through electrochemical impedance spectroscopy, and it was then utilized to develop the fluorometric sensor. The verified OA-specific aptamer was modified with 5-carboxyfluorescein (FAM) as a fluorophore, and graphene oxide (GO) was adopted as the quencher. By virtue of the quenching phenomena between FAM and GO, the developed sensor revealed a low detection limit of 6.35 ppb. Also, this sensor represented a high response to OA compared to other types of marine toxins, such as saxitoxin, domoic acid, and tetrodotoxin.