Green synthesized graphene oxide-zinc oxide nanoparticles for multifunctional biological applications

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A sustainable, biologically inspired strategy was developed for fabricating multifunctional nanocomposites by biosynthesizing zinc oxide nanoparticles (ZnO NPs) using Amaranthus polygonoides L. leaf extract and integrating them onto graphene oxide (GO) sheets. UV–visible analysis recognized the absorption peaks of GO and ZnO NPs. X-ray diffraction (XRD) pattern showed the crystalline nature of GO–ZnO composite. Fourier transform infrared (FT-IR) analysis revealed the important functional groups within the GO–ZnO structure. Scanning electron microscopy (SEM) elucidated the rectangular-needle-like morphology of ZnO NPs and layered structure of GO. Moreover, energy dispersive X-ray (EDX) and mapping analysis exhibited the elemental presence in synthesized materials. The principal finding of this work is the development of a biosynthesized GO–ZnO hybrid system that exhibits synergistic antifungal functionality and scalable environmental sustainability. GO–ZnO achieved complete inhibition of Fusarium oxysporum in chili plants at 1000 µg/mL and provided effective postharvest protection for tomatoes at 250 µg/mL, while maintaining fruit quality and minimizing physiological weight loss. Moreover, GO–ZnO demonstrated broad-spectrum inhibitory activity against diverse phytopathogens at 100 µg/mL, underscoring its versatility across multiple biological systems. By uniting green synthesis, nanoscale engineering and biological applications, the GO–ZnO shows significant potential as a bio-nano control agent for the sustainable agricultural sector.