Preparation of Two-Dimensional Pd@Ir Nanosheets and Application in Bacterial Infection Treatment by the Generation of Reactive Oxygen Species

Noble metal nanozymes have shown great promise in biomedicine; however, developing novel and high-performance noble metal nanozymes is still highly pressing and challenging. Herein, we, for the first time, prepared two-dimensional (2D) Pd@Ir bimetal nanosheets (NSs) with well-defined size and composition by a facile seed-mediated growth strategy. Enzyme-mimicked investigations find that the Pd@Ir NSs possess oxidase (OXD)-, peroxidase (POD)-, and catalase (CAT)-like multienzyme-mimetic activities. Especially, they exhibited much higher OXD- and POD-like activities than individual Pd NSs and Ir nanoparticles (NPs). The density functional theory (DFT) calculations reveal that the adsorption energy of O-2 on Pd@Ir NSs is lower than that on the pure Pd NSs, which is more favorable for the conversion of O-2 molecules from the triplet state (O-3(2)) into the singlet state (O-1(2)). Finally, based on the outstanding nanozyme activities to yield highly active singlet oxygen (O-1(2)) and hydroxyl radicals (center dot OH) as well as excellent biosafety, the as-prepared Pd@Ir NSs were applied to treat bacteria-infected wounds, and satisfactory therapeutic outcomes were achieved. We believe that the highly efficient 2D Pd@Ir nanozyme will be an effective therapeutic reagent for various biomedical applications.

Automated summary

This study prepared two-dimensional Pd@Ir bimetal nanosheets for the first time and found that they possess oxidase, peroxidase, and catalase-like activities. The Pd@Ir nanosheets exhibited higher activities than individual Pd nanosheets and Ir nanoparticles. The density functional theory calculations showed that O-2 molecules are more favorably converted to singlet oxygen on the Pd@Ir nanosheets. Furthermore, the Pd@Ir nanosheets demonstrated excellent nanozyme activities and biosafety when used for treating bacteria-infected wounds.