Effect of the biologically synthesized rGO NPs and Fe2O3/rGO NCs on phytochemical assay, toxicity, and metabolism of Achillea millefolium plant

Biologically synthesized reduced graphene oxide nanoparticles (rGO NPs) and Fe₂O₃/rGO nanocomposites (NCs) were evaluated for their effects on growth and phytochemical responses of Achillea millefolium regenerated shoot cultures. rGO NPs exhibited in vitro cytotoxicity but did not significantly affect overall growth parameters. In contrast, Fe₂O₃/rGO NCs selectively enhanced root elongation at 20 mg/L, indicating a dose-dependent stimulatory response. Both nanomaterials (NMs) caused a reduction in photosynthetic pigment levels. Phytochemical analysis revealed a pronounced increase in volatile metabolite profiles in treated cultures, with Fe₂O₃/rGO NCs showing stronger elicitation than rGO NPs. The highest accumulation of volatile metabolites was observed at 40 mg/L Fe₂O₃/rGO NCs. These findings suggest that Fe₂O₃/rGO NCs, at optimized concentrations, can function as effective elicitors for in vitro enhancement of secondary metabolite production in A. millefolium.