Electrochemiluminescence Immunosensor Based on Confinement-Enhanced Catalysis and Immunorecognition Gating for...

Sensitive detection of prostate-specific antigen (PSA) is clinically important for early prostate cancer diagnosis. Herein, an electrochemiluminescence (ECL) immunosensor was constructed based on the synergistic effect of spatial confinement-enhanced catalysis and immunorecognition gating by confining nitrogen-doped graphene quantum dots (NGQDs) within vertically ordered mesoporous silica nanochannel film (VMSF) through electrophoresis. NGQDs exhibit peroxidase-like activity, efficiently catalyzing reactive oxygen species (ROS) generation from H₂O₂ and amplifying the ECL signal. Following epoxy group functionalization on VMSF's outer surface, PSA antibodies were covalently immobilized to construct a recognitive interface. Specific binding of PSA to antibody forms immunocomplex that introduces steric hindrance, hindering mass transfer of luminol and H₂O₂ and increasing interface resistance. This causes ECL signal decrease, enabling the quantitative determination of PSA. The fabricated immunosensor can linearly detect PSA from 0.01 to 100 ng mL^-1 with limit of detection (LOD) of 1.9 pg mL^-1. The immunosensor also demonstrated good anti-interference capability, high stability, and reproducibility. PSA detection in human serum samples was realized. The strategy for the fabrication of immunosensor integrated confinement-enhanced catalysis and gated immunorecognition, showing advantages including simple fabrication, controllable confinement, and no need for antibody label.