Phytogenic Fabrication of Zinc Oxide Nanoparticles via Uraria picta (Jacq.) DC Extract: Structural Insights and Biological Potentials

Abstract

We report the first successful biogenic fabrication of zinc oxide nanoparticles (ZnO‐NPs) utilizing the aqueous extract of Uraria picta (Jacq.) DC as a sustainable, multifunctional mediator. Synthesis was optimized at pH 9.7 and 80°C, followed by calcination at 500°C to ensure high crystallinity. Comprehensive structural analysis via x‐ray diffraction (XRD) confirmed a pure hexagonal wurtzite phase with an average crystallite size of 33.02 nm. Optical characterization revealed a distinct blue shift with an absorption peak at 310 nm, corresponding to an expanded optical band gap of 4.00 eV. Morphological profiling through HR‐TEM and SEM‐EDX identified rod‐shaped and stacked sheet‐like architectures. Elemental analysis confirmed a high‐purity composition consisting of 79.28% zinc and 20.72% oxygen. Biologically, the ZnO‐NPs displayed potent, concentration‐dependent antibacterial efficacy, achieving maximal zones of inhibition of 17.67 ± 0.57 mm against Bacillus subtilis and 14.00 ± 0.00 mm against Escherichia coli at 100 µg concentrations. While DPPH assays indicated limited antioxidant potential (3.73% inhibition at 320 µg/mL; IC50 > 320 µg/mL), the overall findings establish these phytogenic ZnO‐NPs as high‐performance, eco‐friendly agents for targeted biomedical and antimicrobial applications. This work provides a definitive framework for transforming the bioactive profile of U. picta into sophisticated functional nanomaterials.