Electrochemical Biosensor for the Dual Detection of Tetrodotoxin and Saxitoxin in Seafood Samples: A Multiplexed Device for Toxin Monitoring

Abstract Tetrodotoxin (TTX) and saxitoxin (STX) are two highly potent neurotoxins that can accumulate in seafood, posing serious risks to food safety and public health. Despite being regarded as independent hazards, their documented co-occurrence in seafood underscores the urgent need for new analytical tools enabling their simultaneous detection. Here, a multiplexed electrochemical immunosensor for dual detection of TTX and STX is presented as a novel solution to this challenge. The device combines two distinct magnetic bead-based immunoassays on an electrode array and incorporates internal toxin thresholds aligned with current regulatory or recommended maximum permitted limits for both toxin families. After optimization of the immunoassays, standardization of analytical parameters, evaluation of matrix effects, and validation of system accuracy, 40 seafood samples were analysed, and the results were benchmarked against reference instrumental techniques. The biosensor not only reliably identified the presence of TTX and/or STX in the samples but also determined whether toxin contents exceeded established safety limits. This dual-detection platform represents an important step toward integrated monitoring systems capable of simultaneously tracking multiple marine toxin families in a single analysis run.