An efficient aggregation-induced electrochemiluminescent immunosensor by using TiO₂ nanoparticles as coreaction...

Herein, we fabricated a label-free ECL immunosensor for aflatoxin B₁ (AFB₁) detection. In this system, a small organic aggregation-induced electrochemiluminescence luminophore, 2,5-di-tetraphenylethylene-ylthiazolo [5,4-d] thiazole, was designed, named TPETTZ. Polyaniline-wrapped TiO₂ nanoparticles (PANI/TiO₂ NPs) complex was synthesized through one-step in situ oxidation polymerization of aniline, and performed excellent electrical conductivity and abundant amino groups. As an ECL accelerator, TiO₂ nanoparticles (TiO₂ NPs) promoted the oxidation of tri-n-propylamine (TPA) to generate more TPA^•; in addition, it also acted as a donor to improve the ECL intensity of TPETTZ (acceptor) through electrochemiluminescence resonance energy transfer (ECL-RET). Encouraged by the above, under the existence of TPA, TPETTZ displayed a strong and continuously stable ECL_anode signal due to the introduction of PANI/TiO₂ NPs. Therefore, the immunosensor was constructed for AFB₁ detection based on the quenching effect of target on the ECL signal, and a linearly decreasing ECL signal was obtained as the increasement of AFB₁ in the range of 75 fg/mL to 100 ng/mL, with a lower detection limit of 27.5 fg/mL. Moreover, the as-prepared sensing platform performed a satisfactory anti-interference, stability, and reproducibility, and appeared a good accuracy in walnut sample analysis, presenting a promising application in the future.