A sensitive electrochemiluminescence immunosensor based on Ru(bpy)32+ in 3D CuNi oxalate as luminophores and graphene oxide-polyethylenimine as released Ru(bpy)32+ initiator

In this work, electrochemiluminescence (ECL) luminophor Ru(bpy)32+ was encapsulated in 3D CuNi oxalate and the synthesized metal-inorganic frameworks {[Ru(bpy)3][Cu2xNi2(1−x)(ox)3]}n (Ru/Cu/Ni) exhibited excellent and stable ECL signals, which could be decreased by polyethylenimine capped graphene oxide (GO-PEI). Based on this, a new sandwich ECL immunosensor was developed for detection of carcinoembryonic antigen (CEA). To capture primary antibody and second antibody more simply and efficiently, Ag nanoparticles were doped with Ru/Cu/Ni and GO-PEI. After a sandwich-type immunoreaction, a remarkable decrease of ECL signal was observed due to the release of Ru(bpy)32+ which was caused by the coordination between PEI and metal ions. Under the optimization of determination conditions, a linear response range for CEA from 0.1 pg mL−1 to 100 ng mL−1 was obtained, and the detection limit was calculated to be 0.027 pg mL−1 (S/N=3). The prepared CEA immunosensor displayed high sensitivity, excellent stability and good specificity.