Detection of paralytic shellfish toxins and tetrodotoxins in shellfish using a single-cell biosensor based on patch clamp technology

Paralytic shellfish toxins (PSTs) are a well-known group of potent neurotoxins that may accumulate in shellfish, posing a significant risk to food safety and public health. To protect consumers, shellfish production areas are subject to regulatory monitoring programs targeting PST contamination. However, tetrodotoxins (TTXs), another group of potent neurotoxins that may also accumulate in shellfish and co-occur with PSTs, are not currently included in regulations and routine monitoring schemes in most EU countries. This is of particular concern because PSTs and TTXs share the same biological target and mechanism of action and therefore pose a comparable neurotoxic risk. In this work, we present an automated patch clamp (APC) single-cell biosensing device as a toxicological bioanalytical solution addressing the need for tools capable of simultaneously detecting these two hazardous toxin groups. The biosensor was able to detect not only saxitoxin (STX) and TTX, but also their toxic analogues. The method achieved a limit of detection of 37 µg STX equivalents (equiv.) kg⁻¹, well below the current regulatory limit of 800 µg STX equiv. kg⁻¹. After the analysis of more than 70 samples exhibiting diverse toxin profiles, the results and correlations with reference methods demonstrate that APC single-cell biosensing provides a robust and integrative tool for the simultaneous monitoring of PSTs and TTXs.