Green synthesis of zinc oxide nanoparticles by using Mentha spicata and Ocimum basilicum leaves: Physical properties, foliar treatment, plant uptake and antibacterial potential

Abstract

In this study, plant extracts were used as stabilizing agents to synthesize ZnO-NPs with a green chemistry approach. The plant extracts were obtained from the aromatic plants of mint and basil leaves. The physical properties of the produced nanoparticles were investigated using XRD, SEM and FTIR. The shape of ZnO-NPs was triangular, as revealed by SEM analysis. The effects of biologically synthesized ZnO-NPs on plants when they reach the soil were investigated on the growth of wheat. In addition, antibacterial potential of ZnO-NPs on gram-positive and gram-negative bacteria was investigated. Results showed that S. aureus was more sensitive to all three types of ZnO-NPs than E. coli. Synthesized ZnO-NPs were also given as foliar treatment in order to determine Zn+ 2 uptake by plants and potential toxic effects on the growth of wheat. M-ZnO-NPs and B-ZnO-NPs improved the germination percentage of wheat at 400 mg/L concentration (100%), while raw ZnO-NPs showed 90% germination at the same concentration. It was also revealed that plant growth varies depending on the species and concentrations of ZnO-NPs, therefore, if foliar treatments are applied to wheat, the threshold concentrations, sizes and species of ZnO-NPs should be carefully evaluated.