CuO/ZnO nanocomposites synthesized using Ensete ventricosum extract: antibacterial and antioxidant activity

Most infection-causing pathogens have developed resistance to conventional antibiotic treatments, while free radicals can also induce cellular damage by disrupting essential biomolecules and cellular structures. Binary metal oxide nanocomposites have attracted increasing attention due to their unique physicochemical properties, enhanced stability, and superior biological and catalytic performance compared to single metal oxides. In this study, CuO/ZnO nanocomposites were successfully synthesized via a green, eco-friendly approach using Ensete ventricosum leaf extract, yielding well-defined heterostructures with enhanced biological performance relative to the individual oxides. The UV-Vis spectrum showed an absorption peak at 421 nm with a band gap energy of 3.25 eV, which is slightly lower than that of pure ZnO, indicating a strong interaction between CuO and ZnO phases. The crystallite size was found to be 24.5 nm from XRD analysis, confirming the nanocrystalline nature of the material. FT-IR analysis confirmed the presence of Zn-O and Cu-O stretching vibrations at 545 and 560 cm⁻¹, respectively. SEM analysis revealed slightly agglomerated particles, while EDS confirmed the presence of Zn, Cu, and O elements. The synthesized CuO/ZnO nanocomposites exhibited significant antibacterial activity against Staphylococcus aureus (22.64 mm) and Escherichia coli (19.21 mm), along with strong antioxidant activity (IC₅₀ ≈ 107.18 µg/mL), compared with CuO NPs (~ 150 µg/mL) and ZnO NPs (~ 180 µg/mL) in DPPH radical scavenging assays. These results demonstrate that the CuO/ZnO heterojunction enhances biological activity. This work provides a scalable green synthesis strategy for CuO/ZnO NCs with promising antimicrobial and antioxidant applications, highlighting the potential of plant-mediated routes for environmentally friendly nanomaterial synthesis.