A CeO₂-matrical enhancing ECL sensing platform based on the Bi₂S₃-labeled inverted quenching mechanism for PSA...

In this paper, amidogen graphene (NH₂-Gr) and Au nanoparticle (NP) functionalized cerium oxide (CeO₂) NPs (NH₂-Gr/Au@CeO₂) have been synthesized. The prepared NH₂-Gr/Au@CeO₂ exhibits strong electrochemiluminescence (ECL) activity which could be quenched efficiently by bismuth sulfide (Bi₂S₃). Based on this principle, a novel sandwich ECL immunosensor was constructed for the detection of prostate specific antigen (PSA). NH₂-Gr was used as a loading matrix for CeO₂ NPs because of its superior conductivity and a large surface area. Au NPs were used to combine anti-PSA 1 (Ab₁) to CeO₂via the Au-NH₂ covalent bond and meanwhile to enhance the sensitivity of the immunosensor. NH₂-Gr/Au@CeO₂ was used as the ECL response layer. Ag NP functionalized Bi₂S₃ was used to label the secondary antibody (Ab₂). After a sandwich-type immunoreaction, a remarkable decrease of the ECL signal was observed. The signal-off sensor showed a wide linear range response from 1 pg mL^-1 to 10 ng mL^-1 with a low detection limit (LOD) of 0.3 pg mL^-1. The applicability of the proposed ECL immunosensor was evaluated by detecting PSA in human serum samples.