Biogenic Copper Oxide Nanoparticles Suppress Biofilm Formation and luxS Expression in Multidrug-Resistant Pseudomonas aeruginosa

Abstract Multidrug-resistant Pseudomonas aeruginosa leads to hard-to-manage infections, mainly because of its ability to form biofilms. Therefore, we synthesized copper oxide nanoparticles (CuO NPs) via a eco-friendly method and characterized them using dynamic light scattering and zeta potential analysis. We then assessed their antibacterial and anti-biofilm properties against bacteria isolated from patients, including some multidrug-resistant strains. We also evaluated their effect on bacterial quorum sensing by examining the luxS gene expression by qRT-PCR. We also examined CuO NPs for cytotoxicity to normal human skin cells (HdFn) and bladder cancer cells (UBC-40). The CuO NPs were nanosized in range, they all had a relatively satisfactory zeta potential measure and size profile suggesting a reasonable stability. CuO NPs displayed antibacterial activity, indicated by MIC values around 64 μg/mL. Anti-biofilm activity was observed with reductions of biofilm formation between 52–85% across the different strains tested. The luxS gene expression qRT-PCR analysis demonstrated a significant reduction in luxS gene expression as evidenced by reduced threshold cycle values (p < 0.0001). Finally, preliminary cytotoxicity profiling indicated that outcomes were variable based on nanoparticle exposure (dosing). However, the CuO NPs were less cytotoxic to healthy skin cells (HdFn) compared to bladder cancer cells (UBC-40).