Photothermal effect enhanced antibacterial activity of CuAl-layered double hydroxides

CuAl-layered double hydroxides (CuAl-LDH) with Cu/Al atomic ratios of 2:1 and 3:1 are prepared by a facile coprecipitation method. The as-prepared CuAl-LDH have hexagonal crystalline structure and possess photo- thermal responsive ability. Upon 808 nm near-infrared laser irradiation for 10 min, CuAl-LDH-3 with a Cu/Al atomic ratio of 3:1 demonstrated rapid temperature elevation of 53 degrees C. Moreover, the dissolution rate of copper ions from CuAl-LDH increases with the increase of Cu/Al atomic ratio, and can be further promoted by irradiation. CuAl-LDHs are noncytotoxic to human umbilical vein endothelial cells and demonstrate excellent photothermal antibacterial performance against Gram-positive bacteria Staphylococcus aureus (S. S. aureus) ) and Gramnegative bacteria Escherichia coli ( E. coli) ) and Klebsiella pneumoniae ( K. pneumoniae), ), respectively. CuAl-LDH-3 displays the better antibacterial capacity attributed to the synergistic effects of the photothermal effect induced release of high concentration copper ions and the generation of reactive oxygen species (ROS). This work offers novel LDH-based antibacterial materials with photothermal and enzymatic effects.