Green Synthesis of ZnO nanoparticles using Nigella sativa seed extract for antibacterial activities

This paper presents zinc oxide nanoparticles (NPs) synthesized using Nigella sativa seeds extract, which is an improbable plant with a rich history and religious value. The prepared nanoparticles were characterized by X-ray diffraction (XRD), UV visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and dielectric and antibacterial analysis. The XRD pattern confirms the hexagonal structure and crystallite size increase as the concentration of zinc sulfate increases. UV analysis shows that the absorbance edge lies between 364 and 376 nm, and the band gap increases with an increase in the concentration of zinc sulfate. The active functional group at 432 cm⁻¹ for the Zn-O bond was analyzed through FTIR. Spherical and irregular pore shapes were observed through the SEM analysis. According to the dielectric experiments, the conductivity of the nanoparticles dropped with frequency, while the dielectric constant and dielectric loss increased. The dielectric experiments showed that the ZnO nanoparticles have a much-improved dielectric response, particularly for the high-frequency band. Due to a significant number of oxygen vacancies in the prepared nanoparticles, both rotation direction polarization (RDP) and space charge polarization (SCP), the dielectric characteristics of ZnO nanoparticles, have improved in the frequency range from 20 Hz to 2 MHz. The high-valued inhibitory zone confirms the substance's potent antibacterial action.