2D Carbon Nitride-Based Electrochemical Aptasensor for Label-Free and Highly-Sensitive Detection of Okadaic Acid in Shellfish

Okadaic acid (OA) is a marine toxin accumulated in bivalves causing severe diarrhetic shellfish poisoning, which has become a huge threaten to human health, food safety, and environmental protection. Therefore, it is highly essential to develop cost-effective and convenient approaches for OA detection. Recent advances in the electrochemical transducer and nanomaterials may provide novel approaches to address this issue. Herein, a label-free electrochemical impedance aptasensor was developed for the sensitive detection of OA in shellfish. Two-dimensional nanomaterials (carbon nitride) conjugated with aptamers were employed as the sensitive element for OA detection, which have been well characterized by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Fourier Transform Infrared Spectrometer (FTIR) and X-ray diffraction (XRD). The obtained aptasensor exhibited a good performance for the OA detection with a wide linearity ranging from 1 × 10-14 mol l-1 to 1 × 10-8 mol l-1. The limit of detection was down to 1 × 10-14 mol l-1. Besides, this aptasensor had a good selectivity towards OA in the presence of other toxins, such as dinophysistoxins (DTX), pectenotoxins (PTX), and yessotoxin (YTX). Meanwhile, it also showed a good reproducibility and stability. The real mussel samples results showed a good recovery rate. The simple and cost-effective sensing strategy to marine toxins could be applied in the fields of seafood safety and water quality control.