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 than that of Ru-N/C (SA = 8.3 U mg). Density functional calculations (DFT) revealed that the distortion of the graphitic plane, caused by Se doping with the sp configuration, promotes the charge accumulation on Ru atoms, being more favorable for the adsorption of HO 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 and 0.0738 mU mL, 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).