Harmful algal blooms (HABs) are increasing worldwide, producing marine toxins that accumulate in bivalves and cause human shellfish poisoning, posing risks to public health and the aquaculture economy. In Europe, routine monitoring focuses mainly on diarrhetic shellfish toxins (DSTs) comprising okadaic acid and dinophysistoxins and paralytic shellfish toxins (PSTs)comprising saxitoxin analogues. DSTs are responsible for frequent harvesting closures and may have chronic toxic effects, while PSTs, although less frequent in Portugal, can cause severe neurological symptoms and death.
Official EU control relies on LC-MS/MS and LC-FLD, which are costly, slow and laboratory-bound. Most rapid tests are antibody-based showing high specificity but poor cross-reactivity toward important toxin analogues (e.g. DTX-2/3 and N-sulfocarbamoyl PSTs), making them unreliable in real blooms. ELISA tests as well as cell and receptor-based assays are laboratory techniques requiring the use of bench top equipment. Thus, currently there are no usable screening tests for DSTs and PSTs that could be employed outside of laboratory settings.
The NANOCEAN project proposes miniaturized nano-optical sensors for rapid, low-cost detection of DSTs and PSTs. The system will integrate ionophore-based chemical sensors and protein phosphatase (PP2A) in nanoemulsions immobilized in hydro-, cryo- or aerogels as disposable test strips, with optical readout via smartphone. The tests will quantify total toxin groups at EU regulatory limits, providing a fast toxicity estimate for field screening.
Proposed tools will support shellfish producers and monitoring agencies by enabling early detection of contaminated stocks, reducing unnecessary closures, and allowing laboratory methods to be reserved for confirmatory analysis.
