A Fluorescence Immunochromatographic Strip Based on Quantum Dot Nanobeads for the Rapid Detection of Okadaic Acid

A fluorescence immunochromatographic strip using quantum dot nanobeads (QDNBs)-monoclonal antibody (McAb) conjugates was developed to rapidly detecting okadaic acid (OA) in shellfish. Under optimal conditions, the linear working range was 0.62–20 ng·mL−1, and the full competitive limit of detection (LOD) was 20 ng·mL−1, corresponding to 160 μg·kg−1 per shellfish, meeting the regulatory limit of European Conformity (EC). The strips could show results in 20 min, had high reproducibility, and were effective within 6 months when stored sealed at 4 °C and 25 °C. Moreover, the strips successfully detected OA in spiked shellfish samples. The reliability of the test strips was further confirmed by enzyme-linked immunosorbent assay (ELISA) which was consistent well with Abraxis imported ELISA (R2 = 0.988). The strips are sensitive, specific, replicable, and ideal for rapidly detecting OA, providing a potential tool that can be further developed to detect OA and other marine toxins in shellfish.