Local electronic environment engineered Ru nanoclusters to boost peroxidase-like catalysis for dual-mode immunoassay

Carcinoembryonic antigen (CEA) serves as an important biomarker for early cancer diagnosis, yet its reliable detection remains a challenge due to the demand for high sensitivity and specificity. A nitrogen-doped carbon nitride material loaded with nanoscale ruthenium clusters (C-N-Ru NCs) was synthesized via a template-assisted high-temperature strategy, enabling the construction of a dual-mode nanozyme platform for the sensitive detection of CEA. Nitrogen doping effectively regulated the electronic environment of the carbon-based support, while the introduction of Ru nanoclusters induced significant electronic structure modulation, which in turn enhanced both peroxidase-like catalytic activity and electron transfer efficiency. Density functional theory (DFT) calculations revealed that the optimized electronic configuration facilitated substrate adsorption and reduced the reaction energy barrier, thereby promoting superior catalytic performance. The fabricated C-N-Ru NCs probes were conjugated with secondary antibodies and integrated into a dual-mode sensing system combining photothermal and colorimetric detection. The colorimetric mode exhibited a broad linear detection range of 0.05-10 ng mL^-1 with a detection limit of 2.61 pg mL^-1, while the photothermal mode offered a linear range of 0.05-10 ng mL^-1 with a detection limit of 5.33 pg mL^-1. This work provides an efficient strategy to enhance nanozyme performance through electronic structure modulation, offering a promising avenue for advanced dual-mode biosensing.