Sensores nano óticos para deteção rápida de toxinas marinhas

The NANOCEAN project aims to develop a simple and sensitive screening test for the rapid detection of DSTs and PSTs 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 PST detection are not sensitive to N-sulfocarbamoyl and decarbamoyl toxins, which dominate toxin profiles in bivalves associated with G. catenatum 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 toxins screening in bivalves. This would allow us to quickly assess whether values of toxin concentration fall within the established regulatory limits. This will permit to surpass the current limitations of the conventional analytical techniques and to modernize DSTs and PSTs detection methods. The solution proposed by the 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 [22]. 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. The NANOCEAN project will contribute to the creation of new knowledge and technologies beyond the state-of-art using the following approach: 1. Novel nano optical sensors incorporating ionophores, ion-exchanger and solvatocromic dyes for detection of PSTs and DSTs; there is currently no similar devices for detection of PSTs and DSTs. 2. Novel sensing schemes for okadaic acid determination using nano optical sensors based on indirect detection of its complexation with metal ions and PP2A inhibition; indirect detection scheme allows obtaining very low detection limits necessary for okadaic acid quantification at the concentrations close to regulatory limits. 3. Novel biosensor combining nano optical sensors based on ionophores and solvatochromic dyes and enzyme (PP2A) for detection of okadaic acid. 4. Synthesis of cryo- and aerogels using natural polysaccharides - galactomannans or arabinogalactans, and their application for the encapsulation of enzyme and immobilization of enzyme and nano optical sensors on the solid support. 5. Implementation of optical signal reading using a smartphone as a mean to ensure portability and low cost of screening tests. 6. Benchmarking of the developed nano optical sensors against the official reference methods of PSTs (STX, dcSTX, GTX5 and C1&2) and okadaic acid detection.