Visible light induced antibacterial and antioxidant studies of ZnO and Cu-doped ZnO fabricated using aqueous leaf extract of Ziziphus mauritiana Lam

Abstract

A cost-effective phytogenic fabrication of zinc oxide (ZnO) and copper-doped zinc oxide (Cu-doped ZnO) using aqueous leaf extract of Ziziphus mauritiana Lam. was successfully demonstrated. The structural, morphological and optical studies have been carried out using various techniques. XPS, XRD analysis and FT-IR spectroscopic studies confirmed the successful synthesis, crystalline nature and purity of synthesized ZnO and Cu-doped ZnO. UV–visible diffuse reflectance spectra showed reduction of band gap energies from 3.11 to 2.54 eV as Cu doping increases from 0% to 5%. SEM images revealed the synthesized ZnO and Cu-doped ZnO are irregular and spherical shaped, respectively. Antibacterial property of the synthesized materials were evaluated against Gram positive Staphylococcus aureus and Gram negative Escherichia coli using different concentrations. This investigation revealed that the synthesized materials were able to inhibit the activity of Staphylococcus aureus better than Escherichia coli under both dark and visible light conditions with the highest inhibition of 9.33 ± 0.58 mm under light irradiation. The synthesized materials were also found to effectively scavenge 2,2-diphenyl-1-picrylhydrazyl radicals in the dark and an enhancement of the scavenging activity was observed under visible light irradiation.