D-band modulated bifunctional PdSn alloy nanozymes for advanced dual-mode biosensing

Abstract

The d-band modulation strategy has emerged as an effective approach for tuning the electronic configurations of nanozymes, thereby boosting their catalytic activity and specificity. In this study, we report the construction of bifunctional PdSn alloy nanozymes integrated with hierarchically porous Mo2C-C carrier for colorimetric/electrochemical dual-mode biosensing. The PdSn nanozyme, engineered through p-d orbital hybridization, exhibits significantly enhanced oxidase-like activity for colorimetric sensing via improved oxygen reduction reaction performance, and pronounced peroxidase-like behavior in the electrochemical assay through efficient hydrogen peroxide (H2O2) reduction. Theoretical calculations revealed that the electronic modulation optimizes antibonding states, facilitating H2O2/O2 adsorption and promoting O–O bond cleavage. Additionally, the porous Mo2C-C support further contributes to signal amplification by improving mass transport and reactant enrichment. Benefiting from this synergistic integration of orbital modulation and hierarchical support design, the dual-mode sensing platform achieves highly sensitive cardiac troponin I (cTnI) detection, particularly through the sandwich-type electrochemical sensor, which achieves an ultralow detection limit of 0.857 fg mL− 1, surpassing most reported methods and exhibiting excellent selectivity, reproducibility and stability, enabling its successful application in the analysis of real serum samples.