Detection of ciguatoxins in fish and algal samples with an electrochemical biosensor

Ciguatera fish poisoning (CFP) is one of the most relevant seafood-borne diseases worldwide. It is caused by the ingestion of fish containing ciguatoxins (CTXs), lipophilic marine toxins produced by microalgae of the genera Gambierdiscus and Fukuyoa that accumulate into fish flesh and through the food webs. CFP is characterized by severe neurological, gastrointestinal, and cardiovascular disorders and affects approximately between 50,000 and 500,000 consumers annually worldwide. Real incidence of CFP is difficult to ascertain, due to under-reporting and misdiagnosis. Here, the first electrochemical immunosensor for the detection of CTXs is presented. Three different monoclonal antibodies (mAbs), two capture (3G8, 10C9) and a detector (8H4), were merged in a sandwich configuration for the combined detection of two main groups of CTX congeners (CTX1B and CTX3C ). Initially, the applicability of the immunosensor has been demonstrated with the analysis of fish samples coming from La Reunion island, providing results that correlate with mouse bioassay and cell-based assay. Then, fish coming from Mediterranean waters were analysed, giving promising results. Finally, extracts from Gambierdiscus and Fukuyoa were screened, allowing the separate detection of the two groups of CTX congeners, and giving new information regarding the toxin production of the genera. The developed bioanalytical tool is user-friendly, and can help to mitigate ciguatera risk, contributing to the protection of consumers health.