Green Synthesis of ZnO Nanoparticles Using Mentha Extract: Physicochemical Characterization and Antibacterial Activity Against Staphylococcus aureus and Pseudomonas aeruginosa

Abstract

This work describes a novel, quick, straightforward, green synthesizing methodology of zinc oxide nanoparticles (ZnO NPs) via mint leaf extract (Mentha) as a natural reducing and stabilizing agent. Characterization of nanoparticles was performed by Fourier-Transformed Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). FTIR findings showed that the bands at 480–500 cm⁻¹ were assigned as Zn-O stretching vibrations, indicating the function of active compounds in reduction and stabilization where hydroxyl and phenolic groups are involved during the process. XRD results suggested crystallization of ZnO as a single phase, with clear evidence that the hexagonal wurtzite structure was obtained, showing no extra phases. The SEM images showed that the ZnO NPs had a predominantly quasi-spherical shape, with a slight tendency to aggregate. The agar diffusion method was used to determine the antibacterial activity of synthesized ZnO NPs against Staphylococcus aureus and Pseudomonas aeruginosa, respectively. This antibacterial effect may be attributed to multiple mechanisms proposed in previous studies, including the possible generation of reactive oxygen species (ROS), which can contribute to oxidative cellular damage and bacterial cell membrane disruption. In conclusion, these results indicate that there is a strong relationship between nanoparticle structures and their antibacterial capability. In this regard, the current work demonstrates a cost-effective and green synthesis pathway coupled with knowledge of microbial activity-influencing factors.