Facile synthesis of thymoquinone enriched Salvadora Persica mediated bimetallic Fe-ZnO nanoparticles and their antimicrobial efficacy against multi-drug resistant pathogens of human skin

The rapid emergence of multidrug-resistant (MDR) skin pathogens such as Staphylococcus aureus (MRSA), Streptococcus pyogenes , Staphylococcus epidermidis , Pseudomonas aeruginosa , Escherichia coli , and Klebsiella pneumoniae has significantly limited the effectiveness of conventional antibiotics, necessitating the development of alternative antimicrobial strategies. In this study, an eco-friendly approach was used to synthesize bimetallic iron oxide‑zinc oxide (Fe/ZnO) nanocomposites using Salvadora persica root extract, followed by functionalization with thymoquinone (TQ), the principal bioactive compound of Nigella sativa . Physicochemical characterization, including UV–Vis spectrophotometry, Fourier-Transform Infrared spectroscopy, X-ray Diffractometry and Scanning Electron Microscopy, confirmed successful synthesis and crystalline nature of the particles with size in the range of 90–240 nm. The synthesized Fe/ZnO NCs TQ-functionalized Fe/ZnO nanocomposites were evaluated for antimicrobial activity using standardized assays, including disc diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). TQ-Fe/ZnO NCs demonstrated enhanced antimicrobial activity compared to pure nanoparticles and free thymoquinone. The maximum zones of inhibition were observed against Gram-positive strains ( S. pyogenes and S. epidermidis , 27 mm) and Gram-negative E. coli and P. aeruginosa (25 mm) at 100 μg/disc. MIC values of TQ-Fe/ZnO NCs ranged between 57 and 138 μg/mL for highly susceptible strains ( S. pyogenes, S. epidermidis, E. coli, and P. aeruginosa . The enhanced activity is attributed to synergistic effects involving reactive oxygen species (ROS) generation, membrane disruption, and thymoquinone-mediated intracellular interference. This research holds promise for contributing significantly to the development of less-toxic, environmentally friendly antimicrobial agents that can alleviate the challenges posed by antimicrobial resistance worldwide. • S alvadora persica enabled green synthesis of Fe/ZnO bimetallic nanocomposites. • Thymoquinone was successfully integrated into a Fe/ZnO-based nano-delivery system, as confirmed by UV–Vis, FTIR, and SEM. • TQ-Fe/ZnO nanocomposites exhibited significantly enhanced antibacterial activity compared with standard antibiotics. • Broad-spectrum efficacy was demonstrated against major MDR skin pathogens ( S. aureus , S. pyogenes , P. aeruginosa , E. coli, K. pneumonia ). • Nano-enabled delivery significantly improved thymoquinone therapeutic performance.