Enhanced Multiple Enzymelike Activity of PtPdCu Trimetallic Nanostructures for Detection of Fe2+ and Evaluation of Antioxidant Capability

Metallic nanozymes attracted broad interest because of their efficient catalytic activities and wide applications in biological detection and therapeutics. In this study, PtPdCu trimetallic nanoalloys (TNAs) are prepared by chemical coreduction of Pt2+, Pd2+, and Cu2+ in an aqueous solution. The formation of PtPdCu TNAs is characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive system (EDS), and X-ray photoelectron spectroscopy (XPS). Compared to PtPd bimetallic nanoalloys (BNAs) and commercial Pt/C, PtPdCu TNAs have enhanced enzymelike activities, including peroxidase, oxidase (ferroxidase), and catalase, as well as increased DPPH free radical scavenging ability. Due to the synergistic effect between heteroatoms, the incorporation of Cu into Pt and Pd to form trimetallic structure not only exposes more active surfaces but also causes a change in the electronic structure, which is beneficial to improve the enzymelike catalytic activity. Using the ferroxidase-like and peroxidase-like activity of PtPdCu TNAs, we demonstrate the applications of PtPdCu TNAs in selective detection of Fe2+ in oral supplements and evaluation of the antioxidant capacity of natural antioxidants and tea extracts. Three natural antioxidants tannic acid (TA), gallic acid (GA), and ascorbic acid (AA) are found to show different inhibitory behaviors on peroxidase-like activity of PtPdCu and share the order of antioxidant capability TA > GA > AA.