Synthesis of zinc oxide nanoparticles using the leaves extract of Rhamnus prinoides and its antibacterial activities

Zinc oxide nanoparticles (ZnO NPs) are used in many applications. ZnO NPs were synthesized from 20 mL of Rhamnus prinoides plant leaves extract, 0.1 M of Zn (NO3)2.6H2O precursor and 0.5 M of NaOH as a precipitator by the green synthesis method. The synthesized ZnO NPs were characterized by UV–Visible, Fourier Transform Infrared (FTIR) and X-ray diffraction (XRD) spectroscopic methods. The Rhamnus prinoides, traditionally used as a medicinal plant contains phytochemicals, that were screened qualitatively and by FTIR spectroscopic method. The antibacterial activity of ZnO NPs was evaluated by the disc diffusion method. Plates containing nutrient agar were swab with Gram positive and Gram negative bacteria and soaked with distilled water, Rhamnus prinoides plant extract, ZnO NPs and gentamicin separately and then incubated for 24 h. At the end of incubation, the zone of inhibition (ZOI) was measured. The formation of ZnO NPs was indicated by color change that turned from colorless solution to light yellow. The UV–Vis spectrum indicated an absorbance of 270 nm for the plant extract and 300 nm for ZnO NPs that proves the formation of nanoparticles and the FT-IR spectrum at 433 cm–1 indicated the formation of Zn–O bond. The diameter of ZOI using the synthesized ZnO NPs, plant extract and gentamicin were 22 mm, 12 mm and 25 mm, respectively for Gram negative (Escherichia coli) bacteria and the corresponding ZOI using the synthesized ZnO NPs, plant extract and gentamycin were 20 mm, 11 mm and 24 mm, respectively for Gram positive (staphylococcus aureus) bacteria. The synthesized ZnO NPs showed excellent antibacterial activity for both Gram positive and Gram negative bacteria. The antibacterial activity of the synthesized ZnO NPs was greater than the plant extract alone, but it was slightly less than gentamicin.