Enhanced Antibacterial Efficacy of Copper Single-Atom Catalysts on a Two-Dimensional Boron Nitride Platform

Copper-based antibacterial systems leverage reactive oxygen species (ROS) for effective pathogen control but are limited by issues such as cytotoxicity and resistance due to Cu ion release. By anchoring copper single-atom catalysts (Cu SACs) on biocompatible boron nitride (BN) nanosheets, we create a stable, high-efficiency antibacterial platform that minimizes Cu-ion-induced cytotoxicity and bacterial resistance. This configuration maximizes metal utilization and enhances photocatalytic efficiency for ROS generation, including hydroxyl radicals and superoxide anions. The defect-assisted covalent bonding between Cu and BN ensures stable coordination, preventing metal ion dissolution. First-principles quantum calculations at the level of density functional theory (DFT) provided critical insights into the structures and mechanisms of ROS generation, showing how atomic-level interactions between Cu and BN surfaces boost catalytic activity and clarified electron transfer processes and adsorption energies essential for ROS formation. These insights explain the observed catalytic behaviors and provide valuable design principles for developing efficient, low-toxicity SAC-based antibacterial systems. Additionally, we studied other elements in the same row (Cr, Mn, Fe, Co, Ni, and Zn) experimentally and theoretically. The d-BN-Cu system rapidly inactivated E. coli (10⁶ CFU mL^-1), achieving significant results with d-BN-Cu₁ (Cu, 0.26 at. % with Cu nanoclusters) within 15 min, and d-BN-Cu₃ (Cu, 0.024 at. % with Cu SAC) within 30 min when exposed to sunlight. Although higher copper content can achieve better antibacterial effects, it also brings other potential risks, such as metal ion leaching and higher cytotoxicity. This risk can be effectively avoided by utilizing SACs, as all of the Cu SACs are securely anchored at the defect sites in h-BN through covalent bonds. Cell toxicity testing and in vivo testing emphasize the unique advantages of d-BN-Cu₃ (SAC) in balancing safety and efficiency. This SAC two-dimensional platform can not only effectively combat Gram-negative and Gram-positive bacteria but also effectively avoid the toxicity caused by the metal itself.