NANOCEAN aims to develop a simple and sensitive screening test for the rapid detection of paralytic shellfish toxins (PSTs) and diarrhetic shellfish toxins (DSTs) in bivalve tissues. Currently, portable analytical tools that could be employed outside the laboratory by inexperienced users are not available for either DSTs or PSTs. Furthermore, existing rapid tests for PSTs detection are not sensitive to N-sulfocarbamoyl and decarbamoyl toxins, which dominate toxin profiles in bivalves associated with G. catenatum algae blooms, common in Portugal and other coastal regions worldwide. 

The main objective of this project is to fill this gap by developing sensing tools capable of qualitative or semi-quantitative detection of DSTs and PSTs, which, thus, can be used for toxin screening in bivalves. This would allow us to quickly assess whether values of toxin concentration fall within the established regulatory limits and will permit to surpass the current limitations of the conventional analytical techniques, and to modernize DSTs and PSTs detection methods. 

The solution proposed by NANOCEAN consists in the development of a disposable test employing sensitive nanospheres. Nanospheres comprise dissolved in the organic phase ionophore that binds with the target ions in a reversible and selective way, the ion exchanger that provides ionic sites to keep the electroneutrality of the sensing phase and an optical transducer molecule that is required to indicate the chemical binding. Electrically charged solvatochromic dyes have been recently introduced as indicators of the ion-transfer process. Changes in the target ion concentration alters the distribution of the charged dyes between the nonpolar organic phase of the nanosphere and the polar aqueous phase, being their optical signal changes fluorescence or absorbance. Optical detection can be performed either in the solutions or immobilizing nanospheres on the solid support using hydro, cryo- or aerogels. Signal detection can be done using a common electronic device such as smartphone ensuring portability and low cost of the sensing tool.