Plant-mediated synthesis of silver nanoparticles from Moringa oleifera against ESKAPE pathogens

The emergence of multidrug-resistant ESKAPE pathogens underscores the urgent need for sustainable and effective disinfectant solutions. This study reports the green synthesis of silver nanoparticles (AgNPs) using an aqueous leaf extract of Moringa oleifera, with emphasis on the eco-friendly nature and biocompatibility of the resulting nanomaterials. Seven distinct AgNP formulations were obtained by systematically varying synthesis parameters - including temperature and Ag₂SO₄ and NaOH concentrations - yielding nanoparticles with differentially tunable physicochemical properties. Characterization by UV-visible spectroscopy, dynamic light scattering (hydrodynamic diameter and polydispersity index), zeta potential, and scanning electron microscopy confirmed nanoscale particle formation. Among the synthesized formulations, AgNP 3 exhibited the highest antibacterial activity against ESKAPE pathogens, with minimum inhibitory concentrations (MICs) ranging from 11 to 43.8 μg/mL. Pharmacological interaction analysis revealed additive effects between AgNPs 5 and 6 combined with chlorhexidine against Klebsiella pneumoniae. Furthermore, AgNP 3 inhibited biofilm formation by 49-81% across three bacterial species. In vitro cytotoxicity assays using murine fibroblasts demonstrated high biocompatibility (CC₅₀ > 150 μg/mL), supported by favorable selectivity indices (>4.6). Collectively, these findings suggest that M. oleifera-derived AgNPs may provide a basis for the future development of antimicrobial, antibiofilm, and disinfectant agents targeting pathogens associated with healthcare-associated infections (HAIs).