Bimetallic palladium@copper nanoparticles: Lethal effect on the gram-negative bacterium Pseudomonas aeruginosa

Infections by the gram-negative bacterium Pseudomonas aeruginosa are on the rise, and its antibiotic resistance is a tough challenge for clinical therapeutics worldwide. Therefore, it is an urgent to find alternative antibiotics that possess preferable bactericidal efficiency and are safer than silver (Ag) nanoparticles (Ag NPs). Here, we synthesized small palladium@copper (Pd_1.9Cu) alloy NPs with preferable antibacterial functions. We also used a bacteria-infected skin wound mouse model to confirm the sterilization effect of Pd_1.9Cu NPs. Pd_1.9Cu NPs killed P. aeruginosa at a low concentration, displaying a more powerful bactericidal effect than Ag NPs in vitro. In addition, Pd_1.9Cu NPs broke through the bacterial membrane, leading to DNA fragmentation and leakage of genomic DNA and proteins. The underlying mechanism was to trigger the burst of intracellular reactive oxygen species generation and accelerated ion release (Cu and Pd). Pd_1.9Cu NPs were also more capable of disinfection than Ag NPs and ceftazidime in vivo, promoting speedy wound recovery. Simultaneously, the biocompatibility of Pd_1.9Cu NPs was satisfactory both in vitro and in vivo. These results show that Pd_1.9Cu NPs are a promising nanomedicine to treat P. aeruginosa infection.