Green synthesis and characterization of ZnO nanoparticles using Justicia Schemperiana leaf extract and its antibacterial and antioxidant activity

Abstract

Leaf of the Justicia schemperiana was successively soaked with distilled water and obtained sufficient aqueous concentration yield of extracts. Zinc oxide nanoparticles were synthesized using extracts at 450, 550, and 650 °C calcination temperatures. The obtained biosynthesized zinc oxide (ZnO) nanoparticles were characterized using different spectrophotometric analyses, like UV–Vis, FT-IR, and XRD. The XRD-analyzed results confirmed the hexagonal wurtzite structure of the green-synthesized ZnO nanoparticles with a size of less than 20 nm. The synthesized ZnO nanoparticles using leaf extracts of Justicia schemperiana showed good antioxidant activity and a higher inhibition diameter than the leaf extracts. Moreover, synthesized ZnO nanoparticles at 450 °C shown higher antibacterial inhibition in comparison with ZnO nanoparticles obtained at higher temperatures. The significant antibacterial efficacy of Justicia schemperiana-mediated ZnO NPs stems from several mechanisms, including the generation of reactive oxygen species (ROS) and disruption of bacterial cell membranes. These mechanisms, enhanced by the bioactive compounds present in the plant extracts, enable ZnO NPs to combat a broad range of bacterial strains. Overall, the synthesis of ZnO nanoparticles using Justicia schemperiana leaf extract showed better bacterial treatment systems than the leaf extracts against gram-negative bacterial strains.