Ultrasensitive electrochemiluminescence immunoassay for tumor marker detection using functionalized Ru-silica@nanoporous gold composite as labels

Abstract

In this work, we reported a simple and sensitive sandwich-type electrochemiluminescence (ECL) immunosensor for carcinoembryonic antigen (CEA) on a gold nanoparticles (AuNPs) modified glassy carbon electrode (GCE). The Ru-silica (Ru(bpy)₃²⁺-doped silica) capped nanoporous gold (NPG) (Ru-silica@NPG) composite was used as an excellent label with amplification techniques. The NPG was prepared with a simple dealloying strategy, by which silver was dissolved from silver/gold alloys in nitric acid. The primary antibody was immobilized on the AuNPs modified electrode through L-cysteine and glutaraldehyde, and then the antigen and the functionalized Ru-silica@NPG composite labeled secondary antibody were conjugated successively to form a sandwich-type immunocomplex through the specific interaction. The concentrations of CEA were obtained in the range from 1 pg mL⁻¹ to 10 ng mL⁻¹ with a detection limit of 0.8 pg mL⁻¹. The as-proposed ECL immunosensor has the advantages of high sensitivity, specificity and stability and could become a promising technique for tumor marker detection.