Green Synthesis of Nickel Nanoparticles Using <i>Lawsonia inermis</i> Extract and Evaluation of Their Effectiveness against <i>Staphylococcus aureus</i>

Background: Nanoparticle synthesis uses the green synthesis of nickel nanoparticles (Ni-NPs) because of its low cost, safety, environmental friendliness, simplicity, and ability to treat environmental pollution. Objective: The goal of this work is to make Ni-NPs from Lawsonia inermis (henna) extract so that they can kill bacteria by the diffusion method. Methods: We synthesized Ni-NPs using the hydrothermal method, determining their structure and optical properties through XRD patterns, FESEM images, and UV-visible spectrum analysis. However, the study of the effect of Ni-NPs synthesized from henna extract on antibacterial activity is ongoing. Results: the XRD pattern results proved that the Ni-NPs were synthesized without any other impurities. The FESEM results revealed that the Ni-NPs exhibited a nano-spherical-like shape, with nano-diameters ranging from 11.16 to 401 nm. The optical properties of Ni-NPs are determined by the UV-visible spectrum. The absorbance value of the Ni-NPs synthesized using the henna leaves extract exhibited from 250-290 nm in the UV–Vis spectrum. The inhibition of zone values between 29 and 34 mm on antibacterial activity using Ni-NPs. Conclusions: The results for the diffusion technique showed that because of its improved structure and optical properties, Ni-NPs are a very effective activity material for bacteria.