Eco-friendly fabrication of Mg 0.5 Zn 0.5 Fe 2 O 4 nanoparticles via Annona squamosa -mediated solution combustion for corrosion and biomedical applications

Conventional ferrite synthesis methods often rely on toxic chemicals, hazardous reducing agents, and high-temperature processing, limiting their suitability for biomedical and anticorrosion applications. In this study, magnesium zinc ferrite nanoparticles (Mg₀.₅Zn₀.₅Fe₂O₄; MZF-NPs) were synthesised via an eco-friendly solution combustion route using Annona squamosa leaf extract as a renewable biofuel. X-ray diffraction confirmed the formation of a single-phase cubic spinel structure with an average crystallite size of ∼20 nm. FTIR analysis revealed characteristic Fe–O vibrations, while SEM and TEM showed nearly spherical nanoparticles; EDX verified elemental composition. Optical studies indicated a semiconducting band gap of 1.65 eV. The MZF-NPs exhibited notable biological activities, including dose-dependent anticancer activity against MCF-7 cells (69% inhibition at 100 µg/mL), strong antioxidant performance (DPPH and FRAP IC₅₀ values of 13.65 ± 1.14 and 17.20 ± 1.23 µg/mL, respectively), and effective tyrosinase inhibition (62.3%; IC₅₀ = 24.10 ± 1.38 µg/mL), suggesting cosmetic potential. Electrochemical studies demonstrated corrosion inhibition efficiency of up to 56.5% for mild steel in 1 M HCl, following a spontaneous multilayer physisorption mechanism consistent with the Freundlich isotherm. This synthesis eliminates toxic reagents, lowers energy input, and minimises hazardous waste, highlighting Annona squamosa as a sustainable biofuel for multifunctional ferrite nanomaterial production.