Intrinsic polyphenol oxidase-like activity of gold@platinum nanoparticles

Abstract

Metal nanoparticles (NPs) have received considerable attention in recent years for their unique properties and potential applications in catalysis. However, few studies have employed an integrated approach to investigate the enzyme mimetic activities of metal NPs. The aim of the present study was to evaluate the enzyme mimetic activity of gold@platinum (Au@Pt) NPs. Specifically, the lipoxygenase (LOX), glutathione reductase (GR), glutathione peroxidase (GPx), and polyphenol oxidase (PPO) activities of Au@Pt NPs were examined. The results showed that Au@Pt NPs exhibited PPO mimetic activity over a wider range of pH values and temperatures compared with PPO. Kinetic analysis showed that Au@Pt NPs exhibited higher affinity for certain substrates than the natural enzyme PPO. Furthermore, we also determined the catalytic activity of Au@Pt NPs in the autoxidation of phenol substrates, including pyrogallol, 3,4-dihydroxy-L-phenylalanine, and catechol by electron spin resonance.