Green Fabrication of Zinc Oxide Nanoparticles Using Plant Extracts: Characterization and Evaluation of Biological and Environmental Applications

AbstractPlant-mediated fabrication of zinc oxide nanoparticles (ZnO NPs) is being investigated as analternative to conventional physical and chemical synthesis because plant extracts can providebiomolecules that participate in nanoparticle formation, stabilization and surface capping. Thisreview examines the general principles governing phyto-assisted ZnO synthesis, the principalcharacterization tools used to establish nanoparticle structure and surface properties, and reportedbiological and environmental applications. Particular emphasis is placed on ZnO NPs prepared fromAnnona squamosa L. bark extract. The reported material displayed an optical absorption maximumnear 357 nm, a hexagonal wurtzite crystalline phase, an average X-ray diffraction crystallite size of56.23 nm and a flake-like morphology. Reported biological investigations included antioxidant,antimicrobial, anti-inflammatory, antidiabetic and anticancer assays, while photocatalytic testingagainst methylene blue showed 93.37% degradation after 150 min of sunlight exposure. Thesefindings indicate substantial application potential, but they should be interpreted in the context of thelimitations of preliminary in-vitro and dye-decolourization assays. Reproducible plant authenticationand extraction, quantitative phytochemical profiling, standardized nanoparticle characterization,mechanistic controls, long-term toxicological assessment and scalable process design remainimportant requirements for translation. An integrated approach combining green chemistry,nanomaterial science, analytical characterization and biological validation is therefore recommendedfor the development of reliable phytofabricated ZnO NPs.