Green synthesis and anti-inflammatory properties of zinc oxide nanoparticles from Fe’i and Cavendish banana extracts

Abstract

This study reports plant-assisted green synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous and methanolic extracts of Fe’i (Musa troglodytarum L.) and Cavendish (Musa acuminata) bananas, and evaluates their in vivo anti-inflammatory activity in zebrafish larvae. The extracts were qualitatively profiled and used for the synthesis of ZnO NPs, which were then characterized by UV-vis diffuse reflectance spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy, scanning electron microscopy, and particle-size and zeta-potential measurements. Band-gap energies and structural parameters (crystallite size, lattice constants, and microstrain) were derived from optical and XRD data. All syntheses yielded wurtzite-phase ZnO with absorption maxima at 364–372 nm, band gaps of ∼3.28–3.41 eV, crystallite sizes of ∼14–15 nm, hydrodynamic sizes of 134–689 nm, and negative surface charges of −29.6 to −42.4 mV; SEM revealed flower-like, spherical-like, and snowflake morphologies. Acute toxicity testing in zebrafish gave LC50 values (mg L⁻¹) of 5.65 (PTLA), 16.28 (PTLM), 9.47 (PCVA), and 8.17 (PCVM); LC25 was applied in efficacy assays. In a caudal-fin amputation model, treatment with all ZnO NPs significantly reduced neutrophil counts relative to the negative control (P ≤ 0.05), similarly reduced macrophage recruitment (comparable to dexamethasone), and diminished 48-h fin regrowth (P ≤ 0.05). In conclusion, banana-derived extracts afforded reproducible ZnO NPs with distinct physicochemical signatures and promising anti-inflammatory effects. Although the processing parameters were not fully optimized, these results justify further mechanistic studies and process intensification toward scalable biomedical applications.