Graphene immunosensors for okadaic acid detection in seawater

In this work, we report the fabrication of immunosensors based on field effect transistors with graphene (Gr-FET) for the detection of okadaic acid (OA) in real seawater samples. OA is a marine toxin, and specifically a diarrheic shellfish poison produced by the dinoflagellate species Dinophysis and Prorocentrum. The analytical results obtained with fabricated Gr-FET were compared with those obtained with a traditional methodology (enzyme-linked immunosorbent assay, ELISA) in order to validate the immunosensors for OA detection. Standard solutions of OA with concentrations between 0.05 and 300 ng mL−1 were tested to construct the calibration curve and four spiked real seawater samples were used to validate the immunosensors. With the obtained good reproducibility (0.54-2.19%) and repeatability (0.05-2.06%) as well as low limit of detection (0.05 ng mL−1) and adequate recovery range (98.2-100.7%), the proposed immunosensors are useful for the detection of OA in real seawater samples and could be advantageously extended for detection of other toxins or agents of marine environmental pollution.