Non-toxic immunosensor for highly efficient detection of tetrodotoxin by electrochemical and colorimetric dual-mode sensing platform

Antibody-based immunoassay is an important tool for detecting tetrodotoxin (TTX), a strong neurotoxic with high mortality rate. However, the traditional immunoassays always suffer from low sensitivity, high batch errors of the TTX conjugate and potential harmful to operators. In this work, we fabricated a monoclonal antibody (mAb) with good affinity and high selectivity against TTX, and selected a phage-displayed mimotope with specific binding to the anti-TTX mAb. Based on the mAb and mimotope, a non-toxic and dual-mode (electrochemical and colorimetric signal) immunosensor was developed for the highly efficient and sensitive detection of TTX. A biomimetic mineralized material encapsulated with anti-TTX mAb and HRP (e.g. HRP/anti-TTX mAb@ZIF-8) was used as the recognition element and signal probe. The developed electrochemical/colorimetric dual-mode sensing platform realized the simultaneous sensing of TTX: a wide detection range from 1.0 × 10-4 to 1.0 × 103 μg/mL, with a detection limit as low as 1.0 × 10-5 μg/mL by electrochemical analysis; a linear range from 1.05 × 10-3 - 3.8 × 10-1 μg/mL, accompanied by a detection limit of 1.83 × 10-4 μg/mL by colorimetric analysis based on a smart phone. To the best of our knowledge, we report for the first time on the development of electrochemical/colorimetric dual-mode sensing platform with non-toxic recognizing strategy for detecting TTX, which is highly desirable for detecting and monitoring toxins residue in food samples.