Comparative study of Pickering and conventional emulsions of Zataria multiflora essential oil for antibiofilm activity

Zataria multiflora essential oil (ZEO) exhibits potent antimicrobial activity, yet its pharmaceutical application is limited by volatility, poor aqueous dispersibility, and rapid degradation. In this study, we developed a nanosilica-stabilized Pickering emulsion (PE) to enhance the stability and antibacterial performance of ZEO against clinically relevant nosocomial pathogens. The physicochemical characterization confirmed uniform droplet size, and high kinetic stability (60 days). The ZEO-PE demonstrated significantly stronger antibacterial and antibiofilm activity compared with free ZEO, inhibiting Pseudomonas aeruginosa and Streptococcus pneumoniae biofilms by 83.74% and 77.18%, respectively. Membrane permeability assays (A260 release) and SEM imaging revealed pronounced cell envelope disruption, indicating a PE-mediated enhancement of EO penetration and bactericidal action. Notably, Tween 80 exhibited moderate intrinsic inhibitory effects, which were accounted for in all comparative analyses. Overall, this work demonstrates that Pickering emulsification markedly amplifies the antimicrobial efficacy of ZEO, providing a promising natural nanostructured formulation for combating biofilm-associated infections. To our knowledge, this is the first report detailing the antibiofilm and membrane-disruptive mechanisms of a Z. multiflora Pickering emulsion on nosocomial bacteria.