Biosynthesis and characterization of ZnO NPs using aqueous extract of Zehneria scabra L. leaf for comparing antibacterial activities and the efficacies of antioxidant activities

Abstract

An aqueous leaf extract of Zehneria scabra L. assisted zinc oxide nanoparticles (ZnO NPs) were bio-synthesized from zinc acetate (ZnAc) using eco-friendly and cost-effective synthesis method. The synthesis of ZnO NPs was affirmed by the spectroscopic (Uv-Vis and FT-IR) and microscopic (XRD) techniques. The surface Plasmon resonance of ZnO NPs characterized by Uv-Vis DRS at 380 nm, showing 3.20 eV band gap, FT-IR indicates the effective chelating ability of the plant extract for the synthesizing ZnO NPs, and X-ray diffraction (XRD) showed hexagonal wurtzite characteristic structure corresponding to (100), (002), (101), (102), (110), (103), (200), (112), and (201) planes with strong preferential orientation of wurtzite structure of ZnO NPs along (101) plane. The effects of amount of zinc acetate (ZnAc) (0.5, 1, 1.5, 2.0 and 2.5 mM), adjusted pHs (3, 6, 8, 9, and 12), reaction time (30, 50, 70, 90 and 120 min), and temperature (25 °C -110 °C) on the size of ZnO NPs were studied. The ZnO NPs revealed higher antibacterial activity against gram-positive S. aureus (13 ± 2.0 mm), than gram-negative E. coli (10.33 ± 1.53 mm). The antioxidant activities of ZnO NPs against 1, 1-diphenyl-2-picrylhydrazyl (DPPH) were presented with promising radical scavenging ability at an IC50 of 104 µg/mL. This study further paves the way for the possible preparation of other metal oxide NPs with promising targeted drug delivery potential for biomedical and environmental applications.