A Tb-metal-organic gel enhanced electrochemiluminescence biosensor with a supersandwich DNA walker for okadaic acid detection

Okadaic acid (OA), a potent diarrhetic shellfish toxin produced by marine dinoflagellates, accumulates in shellfish and poses a significant threat to human health by causing severe gastrointestinal illness. Consequently, the highly sensitive detection of OA is of crucial importance. In this study, an electrochemiluminescence (ECL) biosensor for OA detection was developed based on a Tb(Ⅲ)-Cbatpy-MOGs complex and a nucleic acid amplification strategy. The sensor integrates a cyclic DNA walker with the enzymatic assistance of Exonuclease III for accurate target quantification. The ECL intensity showed a strong linear relationship with the logarithm of OA concentration over a wide range, achieving a detection limit as low as 0.16 pg/mL, attesting to its high sensitivity. Furthermore, the biosensor exhibited excellent selectivity, reproducibility and stability, confirming its reliability for practical applications. This work provides a robust and highly sensitive method for OA detection and holds great promise for the practical monitoring of marine toxins.