Green Synthesis of Zinc Oxide Nanoparticles from Aqueous Extracts of Citrus sinensis Peel: Their Characterization and Relevance

Plants and their products serve as a treasure trove of enormous health benefits. The work presents a simple, yet efficient methodology for the green Zinc oxide nanoparticles (ZnO-NPs) synthesis from Citrus sinensis fruit peels. This method seeks to utilize abundantly available agro waste, such as fruit peels, to form value-added biomolecules like minerals and put them into use commercially. The extract from the peels of Citrus sinensis was treated with zinc acetate and sodium hydroxide for the synthesis of ZnO-NPs and was subsequently characterized. Nanocrystal production of ZnO-NPs was determined by XRD and the shape confirmation was determined by SEM analysis. The ZnO-NPs have been studied for their biological importance such as antibacterial and antioxidant properties. An MTT assay was performed to determine the cytotoxic effect on cell proliferation. The XRD analysis provided evidence for nanocrystal formation. The FTIR measurement confirmed the existence of functional groups that contribute to the stability of ZnO-NPs. In the SEM analysis, ZnO-NPs were imaged as well-shaped and spherical. The nanoparticles were also evaluated for their biological significance for antibacterial, antioxidant and cytotoxic activities. The ZnO-NPs demonstrated that antibacterial action is stronger against Gram-positive bacteria than against Gram-negative bacteria. ZnO-NPs were evaluated for cytotoxicity effect on HCT-116 cells and the IC50 value was determined to be 45 μg/ml. These findings can solely be attributed to the well-being of society, as the ZnO-NPs from citrus fruit peels can be used in pharmaceutical applications and can target the reduction of agro waste and as a source of eco-friendly value-added products.