Precision-Engineered Co-N_4-x -C _x Single Atoms Enhance Potential-Resolved Ru(bpy)₃ ²⁺ Electrochemiluminescence via...

Electrochemiluminescence (ECL) immunoassays based on tris(bipyridine)ruthenium [Ru(bpy)₃ ²⁺] is the luminophore representing the most advanced and widely adopted approach in the field of in vitro diagnostics (IVD). However, the scarcity of potential-resolved ECL promoters for Ru(bpy)₃ ²⁺ markedly limits its application in clinical diagnostics. Here, we report the first application of cobalt single-atom catalysts (SACs) designed via density functional theory (DFT) calculations to boost the multi-signal ECL of Ru(bpy)₃ ²⁺. Mechanism investigations unveil that "ROS accumulation" induced by CoC₄ and "ROS surge" driven by CoN₄ are the key factors governing the cathodic and anodic ECL. As a proof of concept, a sandwich ratiometric immunosensor was developed to detect tumor marker CEA and demonstrated excellent clinical feasibility. This work provides insights into the development of tailored ECL promoters by introducing DFT prediction and elucidating the relationships between ORR/HPRR/OER processes and Ru(bpy)₃ ²⁺ ECL behavior, paving the way for designing precise immunoassays and advancing IVD techniques.