Plasmon-enhanced oxidase-like activity and cellular effect of Pd-coated gold nanorods

Local surface plasmon resonance (LSPR) enhanced catalysis has attracted much attention recently. Palladium nanoparticles (PdNPs) have been reported to have various nanozyme activities and exhibit promising potentials for biomedical applications. However, as Pd is a poor plasmonic metal, little attention has been paid to its LSPR-regulated nanozyme activity. Herein, by using Au nanorods (AuNRs) as a strong plasmonic core, we coated a thin layer Pd to form a rod-shaped core-shell structure. The obtained Au@PdNRs showed tunable LSPR bands in the near-infrared (NIR) spectral range inheriting from Au core and yet an exposed Pd surface for catalysis. The oxidase-like activity was investigated in dark and upon SPR excitation. The plasmon-enhanced activity was observed and was mainly ascribed to local photothermal effect. Finally, in order to enhance biocompatibility, mesoporous silica-coated nanorods were used to detect the oxidase-like activity in cells. After being endocytosed by cells, upon plasmon excitation...