Ultrasensitive electrochemiluminescence immunosensor for tumor marker detection based on nanoporous sliver@carbon dots as labels

A sensitive electrochemiluminescence (ECL) immunosensor for detection of prostate protein antigen (PSA) was developed. The three-dimensional (3D) graphene conjugated with gold nanoparticles (AuNPs) (3D-GR@AuNPs) was used to modify glassy carbon electrode (GCE), which provided an effective matrix for antibody immobilization. The 3D-composites were synthesized through freeze drying process and provided larger surface area compared with the conventional 2D structure. The carbon dots (CDs) simply prepared by electrooxidation of graphite was used as ECL reagent. The nanoporous sliver (NPS) with controllable 3D structure could provide a good platform for high loading of CDs, which formed the NPS@CDs composites as good ECL label. The good electrical conductivity of 3D-GR@AuNPs and high loading of CDs of NPS@CDs composites provided the significant advantage of dual-signal amplification technique. The new biosensor displayed good analytical performance for the detection of PSA in the range from 1 pg mL−1 to 50 ng mL−1 with a low detection limit of 0.5 pg mL−1. The sensor showed good reproducibility, acceptable precision and reliable stability, thus could provide many potential applications for the detection of tumor maker in the clinical research.