Biosynthesis of Zinc Oxide Nanoparticles from Musa paradisiaca Peel: Characterization and Antibiotic Synergy against...

This study reports a green synthesis of zinc oxide nanoparticles (ZnONPs) using Musa paradisiaca peel extract and evaluates their ability to enhance the activity of commercially available antibiotics against multidrug-resistant (MDR) Escherichia coli and Klebsiella pneumoniae. ZnONPs were prepared by mixing 30 mL of peel extract with 30 mL of 1 mM ZnSO₄·7H₂O, with the pH adjusted to 10, followed by centrifugation at 3000 rpm for 5 min, washing, and drying in the dark at 25 °C to obtain ZnONP powder. The synthesized ZnONPs were characterized using UV-Vis spectroscopy, scanning electron microscopy-energy dispersive analysis of X-rays (SEM-EDAX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). A characteristic UV-Vis absorption peak at 450 nm confirmed ZnONP formation, while XRD indicated a crystalline structure with an average crystallite size of 32 nm. SEM revealed irregular, monodisperse particles, and EDAX confirmed Zn as the dominant element along with signals attributable to organic and mineral components from the peel extract. FTIR suggested that phenolic, hydroxyl, and carboxyl functional groups in the extract likely contributed to nanoparticle reduction and capping. In antibacterial assays, ZnONPs alone produced inhibition zones of 17 ± 1.54 mm against E. coli and 26 ± 1.73 mm against K. pneumoniae. ZnONPs significantly enhanced antibiotic activity compared with non-coated discs (p = 0.01), increasing inhibition by 42.5-55.7% against E. coli and 42.9-52.7% against K. pneumoniae. These findings support the potential of banana peel-derived ZnONPs as low-cost synergistic enhancers of existing antibiotics against MDR pathogens.