The sustainable synthesis of metal oxide nanomaterials is a growing demand in nanobiotechnology, where ecological routes must deliver reproducible control over composition, crystallinity, and bioactivity. Here, we report the first green synthesis of zinc oxide nanoparticles (ZnOMO NPs) using the aqueous extract of Myrcia oblongata DC, a native Myrtaceae species rich in polyphenols and terpenoids. Beyond introducing this novel plant-based route, the study provides insights into how specific phytochemical groups – especially phenolic and terpenoid compounds – can mediate Zn2+ complexation and hydrolysis, nucleation, and surface stabilization, contributing to a broader understanding of plant-assisted ZnO formation. The biosynthesized nanoparticles were systematically characterized by FTIR, XRD, DLS, HRTEM, UV–visible spectroscopy, photoluminescence (PL), and TGA. The ZnOMO NPs exhibited a hexagonal zincite structure, high crystallinity, and an organic surface layer (≈ 45%) derived from plant metabolites, as confirmed by TGA and phenolic quantification (33. 06 µg GAE mg⁻¹). UV–Vis and PL analyses revealed characteristic optical features of biofunctionalized ZnO nanostructures, indicating the presence of surface- and defect-related electronic states associated with the phytochemical capping. Compared to commercial ZnO NPs, ZnOMO NPs displayed over twofold higher antioxidant capacity (690. 6 vs. 311. 2 µmol TE g⁻¹ in the ABTS assay) and a markedly lower polydispersity index (0. 087 ± 0. 014), indicating enhanced colloidal homogeneity. Cytotoxicity assays revealed preferential toxicity toward glioblastoma (U87) cells while maintaining biocompatibility with non-tumoral keratinocytes (HaCaT), demonstrating a moderately selective and biocompatible therapeutic profile (SI₅₀ ≈ 1. 45). These findings establish M. oblongata as a novel phytochemical platform for engineering multifunctional, biofunctionalized ZnO nanostructures and highlight the potential of green nanotechnology to generate biocompatible and selective materials for future biomedical applications.
Halfeld et al. (Tue,) studied this question.