Green and Ecofriendly Mycosynthesis of Nanocomposite Based on Zinc and Magnesium Oxide Nanoparticles Using Endophytic Sarocladium kiliense: Characterization, Anticancer Activity, Antimicrobial and Antibiofilm Activities

Fungal species are increasingly recognized as efficient bio‐factories for the biosynthesis of nanoparticles with distinctive functionalities. In this study, zinc oxide‐magnesium oxide nanocomposite (ZnO‐MgO NCs) were biologically created employing the Sarocladium kiliense PV248633.1 fungal strain. Ultraviolet‐visible spectroscopy confirmed nanoparticle formation through characteristic absorption peaks, while Fourier‐transform infrared spectroscopy identified functional groups associated with metal‐oxygen bonds. Also, the nanoparticle size and surface characteristics Transmission electron microscopy and dynamic light scattering analyzes revealed an average particle size of 35 nm. Biological assessments demonstrate potent antitumor activity (IC₅₀ = 78.1 µg/mL) against MCF‐7 breast cancer cells, alongside minimal cytotoxicity against normal WI‐38 cells (IC₅₀ = 218.7 µg/mL), indicating selective toxicity. Antibacterial evaluations showed particularly high efficacy against Acinetobacter baumannii and Pseudomonas aeruginosa occasionally surpassing the performance of cefepime. Dose‐dependent antimicrobial activity was confirmed through well diffusion and broth microdilution techniques, with minimum inhibitory concentrations highlighting strong bactericidal potential. Biofilm inhibition assays revealed strain‐specific responses, with A. baumannii being the most susceptible. Furthermore, the synergistic combination of the biosynthesized nanocomposite with cefepime enhanced antibacterial outcomes against selected isolates, suggesting potential for addressing drug resistance. Overall, the mycogenic ZnO‐MgO NCs synthesized from S. kiliense exhibited substantial anticancer, antibacterial, and antibiofilm properties, locating this nanocomposite as a promising candidate for biomedical purposes.