Scheme 1.

Schematic representation of ZnOFe biosynthesis from Olea europaea leaf extract (OLE). Phenols and flavonoids are the major constituents of aqueous OLE extract. The abundant medium served as a reducing/chelating agent for the biosynthesis of ZnOFe nanoparticles. After the bioreduction of metal ions (Zn²⁺, Fe²⁺) and growth of the resulted nanoparticles, specific compounds from the phytoconstituent-rich extract with different terminal groups (X,Y,Z: CO, COC, COOH, OH, C–C groups) act as stabilizers or capping agents, covering nanoparticles surfaces in order to prevent further agglomeration (red ring around nanoparticles).