Quantitative proteomic and phenotypic responses of urinary pathogens to CuO/Cu₂O nanoparticles

To evaluate the antibacterial efficacy of pulsed laser ablation-generated copper oxide (CuO/Cu₂O) nanoparticles (NPs) against urinary pathogens and to elucidate molecular stress responses through proteomic profiling.

Enterococcus faecalis, Proteus mirabilis, Escherichia coli, and Pseudomonas aeruginosa were exposed to CuO/Cu₂O NPs. Viability was assessed by colony-forming unit counts, while morphological alterations were examined using field emission scanning electron microscopy (FESEM). Quantitative proteomic analysis with COG and KEGG bioinformatics was performed for E. faecalis and P. mirabilis at early exposure times (10-60 min).

CuO/Cu₂O NPs significantly reduced viability, with E. coli and P. aeruginosa fully inhibited after 30 min, whereas P. mirabilis showed relative resistance. FESEM revealed nanoparticle-induced membrane rupture and cell deformation. Proteomic analysis identified conserved and species-specific stress responses. Shared adaptations included upregulation of energy metabolism, transcription, and transport pathways. E. faecalis uniquely increased carbohydrate metabolism and cell wall biogenesis, while P. mirabilis emphasized ribosome biogenesis, ion transport, and nucleotide metabolism. Virulence-associated proteins were differentially expressed, linking stress adaptation to pathogenicity.

CuO/Cu₂O NPs exert rapid antibacterial activity via oxidative stress, membrane disruption, and metabolic reprogramming. Distinct proteomic adaptations explain species differences in susceptibility and highlight copper nanoparticles as promising antimicrobial candidates.