Core-shell Au@Pd plasmonic nanozyme for enhanced broad-spectrum antibacterial activity and effective microbial discrimination

The development of plasmonic nanozymes with light-controlled catalytic activity is crucial for advancing antibacterial therapy and microbial identification. Herein, we synthesized core–shell Au@Pd nanoparticles (Au@Pd NPs) with plasmon-enhanced activity for bacterial elimination and detection. The thin and porous Pd shell of Au@Pd NPs provided active sites and allow sufficient light to reach Au core. Under visible light, the peroxidase (POD)-like activity of Au@Pd NPs was significantly enhanced, with K m values decreased by 10 % (for TMB) and 15 % (for H 2 O 2 ), while V max increased by 2.1- and 2.8-fold, respectively, compared to dark conditions. The enhanced POD-like activity of Au@Pd NPs, mainly attributed to the hot charge carriers that enable efficient reactive oxygen species (ROS) generation, achieved 100 % killing efficiency against both Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ). By contrast, killing rates reached only 90 % for E. coli and 80.1 % for S. aureus under dark conditions, indicating excellent light-responsive antibacterial activity. Moreover, the successful discrimination of six microorganisms was also obtained using the Au@Pd-TMB-H 2 O 2 system. Based on their different inhibitory effects on TMB oxidation, absorbance values at 652 nm and 452 nm were used as the sensing channels to capture the fingerprint spectra of each microorganism. Results of principal component analysis (PCA) and hierarchical cluster analysis (HCA) confirmed enhanced microbial identification under light. These findings highlight the promise of light-activated nanozymes for integrated antibacterial treatment and precise microbial sensing.