A Highly Sensitive Electrochemiluminescence Immunosensor Based on Ru(bpy)₃²⁺/PAMG Composite Carriers and Au-Fc-MOF Quenching Systems for Ultra-trace Detection of Carcinoembryonic Antigen

Early cancer diagnosis is crucial due to a significant increase in cancer incidence over the last three decades. A highly sensitive electrochemiluminescence technique was developed for carcinoembryonic antigen (CEA) detection. This method uses Ru(bpy)32+ as the luminescent substance, and the silica and polyacrylamide gel composite as the carrier. Ru(bpy)32+ is loaded into it to prevent its leakage. At the same time, biological molecules such as antibodies or antigens are immobilized, thereby improving the stability and reaction activity of the system. Additionally, Au-Fc-MOF was synthesized to act as a quencher and secondary antibody label, absorbing the emitted energy from the ECL emitter to improve detection accuracy across various CEA concentrations. Potassium persulfate was employed as a co-reactant to generate SO4•- radicals, intensifying the luminescence output of the system. The findings revealed that the developed immunosensor exhibited strong linearity within the concentration range of 10-5 ng/mL to 10 ng/mL, with a remarkably low detection limit of 5.03 fg/mL. This electrochemical luminescence immunosensor, characterized by its simple preparation, cost-effectiveness, and superior performance, demonstrates significant potential in advancing early CEA detection methodologies.