A Review on the Green Synthesis of ZnO Nanoparticles Using the Aqueous Extract of Origanum Majorana for Antimicrobial Applications

Abstract

Zinc oxide nanoparticles (ZnO-NPs) have been extensively researched for their potential applications in various fields such as pharmaceuticals, cosmetics, biotechnology, sensing, photocatalysis, and photovoltaics due to their unique nanoscale properties. However, the conventional methods for producing ZnO NPs require the use of hazardous chemicals and high energy consumption, which imposes certain limitations. In contrast, the green synthesis of ZnO-NPs using plant extracts, especially Origanum majorana, has gained much attention as a promising alternative approach. Plant extracts contain phytochemicals that are biologically safe and non-toxic, making them a preferred choice. In addition, the ZnO-NPs synthesized with O. majorana extracts exhibit higher stability and can be customized in terms of shape and size, unlike the ZnO-NPs obtained by bacterial or fungal methods. The aqueous leaf extract of O. majorana contains flavonoids, tannins, and phenolic derivatives, which serve as reducing and capping agents for the biosynthesis of ZnO-NPs. These extracts also contain functional groups such as -OH and -C=O, which further enhance the physicochemical properties of the resulting ZnO-NPs and influence their ability to target specific molecules. The plant-mediated synthesis of ZnO-NPs using O. majorana leaf extract is not only fast and straightforward but also offers a wide range of functionalized nanoparticles with specific morphologies and sizes. These ZnO-NPs prepared with O. majorana have been shown to have potential applications in various fields, including antimicrobial, antioxidant, and anticancer activities. This review focuses specifically on the antimicrobial applications of ZnO-NPs synthesized using O. majorana leaf extract.