Abstract
This study presents a green and efficient method for synthesizing zinc oxide (ZnO) nanoparticles using Biancaea sappan leaf extract, marking the first report of this plant's application in nanoparticle fabrication. The extract coated ZnO nanoparticles (BSE-ZnONPs) displayed enhanced multifunctional bioactivity, showing strong antibacterial inhibition against Staphylococcus sp. (45 mm), high anti-inflammatory activity (95.57%), and notable antioxidant potential (78.65% inhibition at 500 µg/mL). Under optimized conditions (200 mg/L, pH 1, 7.5 min ultrasonication), the nanocomposite achieved 98.88% dye degradation efficiency, surpassing similar green-synthesized ZnO systems reported previously (< 95%). The BSE-ZnONPs maintained over 84% efficiency for two reuse cycles and retained moderate activity (42.7%) in the third cycle, confirming good recyclability. Cytotoxicity studies revealed high cell viability in L929 cells (IC₅₀ = 151.48 µg/mL), and in vivo assays using Oreochromis niloticus demonstrated significant mitigation of dye-induced histopathological damage. These results highlight the superior catalytic and biocompatible performance of BSE-ZnONPs and their potential as a sustainable nanotechnological solution for textile wastewater treatment and aquatic ecosystem protection.