Low-Potential Electrochemiluminescence of Carbon Dots Enabled by Co-Mn Bimetallic Atoms for Bioanalysis

Carbon dots (CDs) have emerged as promising electrochemiluminescence (ECL) emitters for biosensing due to their low toxicity, facile synthesis and modification, and good biocompatibility. However, most of the reported CDs require a more negative ECL trigger potential than -1.5 V vs Ag/AgCl, which not only induces undesirable electrode side reactions but also compromises the structural integrity of biomolecules, thus limiting their practical utility in complex biological systems. This study explored a bimetallic atom modulation strategy to significantly shift the ECL excitation potential of CDs positively. Concretely, Co-Mn bimetallic atoms were anchored on ultrasmall nitrogen-doped carbon dots (NCDs) to prepare Co-Mn/NCDs. On one hand, the bimetallic atoms effectively narrowed the bandgap of the material, shifting the ECL excitation potential positively to -0.9 V. On the other hand, the synergistic action of the bimetallic atoms significantly enhanced the decomposition efficiency of S2O82-, promoting the generation of reactive intermediates such as SO4•- and OH•, thereby greatly boosting ECL intensity. The excellent low-potential ECL characteristics of Co-Mn/NCDs were integrated with a CRISPR-Cas12a cascade signal amplification strategy to construct an ECL sensing platform for the highly sensitive detection of the cancer biomarker flap endonuclease 1 (FEN1). This work innovatively introduces bimetallic atoms into the CDs-based ECL system, effectively overcoming the issue of the overly negative excitation potential of CDs and providing an attractive low-potential ECL platform.