Effect of dispersed species heterogeneity in carbon-based catalysts for near-infrared light-responsive synergistic antibacterial therapy

Due to their distinct properties, single atom and cluster catalysts have been intensively researched and developed in several fields. However, the mechanism by which the size of these dispersed species of single-atom and cluster catalysts, as well as conventional particulate catalysts, affects the properties remains ambiguous, especially in complex systems such as photothermal/photodynamic therapy. Therefore, carbon black is chosen as a substrate and loaded with two types of metals (Cu and Au) in sizes ranging from single atoms to nanoclusters and nanoparticles. The Cu-CBs and Au-CBs showed the opposite variation of antimicrobial activity to the dispersed species. The antimicrobial activity of the Cu-CBs decreased with the size of dispersed species from 100% to 99.48% and 99%. The increase in size enhanced the antimicrobial activity of Au-CBs from 95.1% to 97.4% and 98.8%. Characterization and theoretical calculations revealed that the dispersed species of Cu and Au affect the photothermal properties and photodynamic aspects to varying degrees. This work contributes to the development of single-atom and cluster nanomaterials as well as conventional catalysts and the investigation of related mechanisms.