Antibiofilm activity of ZnO–Ag nanoparticles against Pseudomonas aeruginosa

Biofilm-related infections remain a major concern in clinical settings due to the increasing challenge of antimicrobial resistance to conventional antimicrobial treatments. Surface coatings of nanomaterials that can effectively prevent biofilm formation and disrupt established biofilms are essential to addressing this challenge. In this study, a ZnO-Ag nanocomposite was synthesized via a dry chemical method and characterized using XRD, XPS, TEM, SEM-EDX, and AFM, confirming the presence of highly crystalline and pure ZnO and Ag nanoparticles with sharp nanoscale features. The nanocomposite demonstrated potent antibiofilm activity against Pseudomonas aeruginosa, a common Gram-negative biofilm-forming pathogen. Surface-coated glass slides prevented initial biofilm formation, while treatment with higher nanocomposite concentrations (≥ 0.25 g/L) significantly disrupted pre-formed biofilms and altered biofilm architecture, as shown by SEM and crystal violet assays. Mechanistic investigations suggested that nanoparticle surface sharpness may contribute to membrane disruption, and EPR analysis confirmed the generation of reactive oxygen species (ROS), particularly superoxide and methyl radicals, under light exposure. These results highlight the composite's strong potential for integration into surfaces prone to bacterial colonization, offering a practical approach for reducing biofilm-related complications.