Enhanced Peroxidase-like Activity of Ruthenium-Modified Single-Atom-Thick A Layers in MAX Phases for Biomedical Applications

Nanozymes have demonstrated significant potential as promising alternatives to natural enzymes in biomedical applications. However, their lower catalytic activity compared to that of natural enzymes has limited their practical utility. Addressing this challenge necessitates the development of innovative enzymatic systems capable of achieving specific activity levels of natural enzymes. In this study, we focus on enhancing the catalytic performance of nanozymes by introducing Ru atoms into the single-atom-thick A layer of the V₂SnC MAX phase, resulting in the formation of V₂(Sn_0.8Ru_0.2)C with Ru single-atom sites. The V₂(Sn_0.8Ru_0.2)C MAX phase demonstrated an exceptional peroxidase-like specific activity of up to 1792.6 U mg^-1, surpassing the specific activity of a previously reported horseradish peroxidase (HRP). Through X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) investigations, it has been revealed that both the V₂C atom layers and single-atom-thick Sn readily accept a negative charge from Ru, leading to a reduction of the energy barrier for H₂O₂ adsorption. This discovery has enabled the successful application of V₂(Sn_0.8Ru_0.2)C in the development of a lateral flow immunoassay for heart failure biomarkers, achieving a detection sensitivity of 4 pg mL^-1. Additionally, V₂(Sn_0.8Ru_0.2)C demonstrated exceptional broad-spectrum antibacterial efficacy. This study lays the groundwork for the precise design of MAX phase-based nanozymes with high specific activity, offering a viable alternative to natural enzymes for various applications.