Electrochemiluminescence Immunosensor Based on Confinement-Enhanced Catalysis and Immunorecognition Gating for Sensitive Determination of Prostate-Specific Antigen.

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.