Development of a point of care (POC) test as an immunobiosensor for okadaic acid detection in mussels

• Rapid and POC methods • Detection of OA in Mytilus galloprovincialis • ELISA optimization for OA detection in mussels • Development of POC OLED-based immunosensor • Validation of the immunosensor for OA detection in Mytilus galloprovincialis The increase in frequency and intensity of potential risks concerning the exposure of seafood to diarrhetic shellfish poisoning (DSP) toxins, even in areas not traditionally accomplished, raises the number of monitoring analyses for the detection of this class of toxins to guarantee the food safety of the products. In addition to the analysis performed with liquid chromatography-tandem mass spectrometry (LC-MS/MS), reference method in EU, semiquantitative rapid tests for preliminary screening and rapid monitoring plan are applied. Different kits for the detection of DTX family toxins are available on the market, but they require specialised labs and the cost of the analysis per sample is quite high. Based on the current situation, developing an easy-to-use and cheap test for measuring okadaic acid, as the main responsible for DSP poisoning, for the implementation of point-of-care (POC) systems is desirable. An immunobiosensor test, based on immunoaffinity reaction utilizing commercially available monoclonal antibodies, has been optimized and validated for the detection of okadaic acid in mussel ( Mytilus galloprovincialis ) extracts, with a limit of detection of 60 µg/kg, a sensitivity of 0.68 n° of counts/ ug/Kg and a screening test range between of 60-350 ug/kg. The proposed POC immunoassay provides results comparable (r=0.981) to the ones obtained by other semiquantitative rapide tests, like enzymatic assay applied for routine monitoring plans for the detection of the dinophysistoxins (DTXs) family. The goal of the presented test is the reduction of steps for the toxin extraction and a relevant reduction of the time for the analysis and the provision of a cheap POC analysis system.