Structural Undulations Induced by Se Doping Boost Peroxidase-Like Activity of Ru Single-Atom Nanozymes for Biosensing

Mimicking the structure of natural enzymes can reproduce their similar high catalytic activity. Herein, Ru-Se dual single atomic sites on nitrogen-doped carbon catalysts (RuSe-N/C) are fabricated by an atomic capture strategy. Se atoms replace partial pyridinic N sites in RuSe-N/C, which results in undulating structure and high structural similarity to β-sheets in the protein. RuSe-N/C shows a significant enhancement of peroxidase (POD)-like activity with specific activity (SA) of 94.3 U mg^-1 than that of Ru-N/C (SA = 8.3 U mg^-1). Density functional calculations (DFT) revealed that the distortion of the graphitic plane, caused by Se doping with the sp³ configuration, promotes the charge accumulation on Ru atoms, being more favorable for the adsorption of H₂O₂ and *OH, thereby boosting the POD-like activity. Based on the superior POD-like activity of RuSe-N/C, a dual-mode biosensing platform was developed for colorimetric and photothermal determination of alkaline phosphatase (ALP) activity with detection limits (LOD) as low as 0.0102 mU mL^-1 and 0.0738 mU mL^-1, respectively, outperforming most POD-like nanozyme-based ALP sensing platforms. This study not only offers a new strategy but also provides a new route to designing high-efficiency single atom nanozymes (SAzymes).