Green synthesis and characterization of nanocrystalline Ni-Co spinel ferrites using Vitex negundo leaf extract for biomedical applications

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The high colloidal integrity and biocompatibility are fundamental prerequisites for the successful integration of magnetic nano ferrites in advanced biomedical modalities. This study presents a novel and environmentally conscious approach for synthesizing Ni-Co mixed spinel ferrites with the specific stoichiometry of Ni 0.5 Co 0.5 Fe 2 O 4 using the phytochemical-rich Vitex negundo leaf extract as a natural green reductant and capping agent. The synthesized nanoparticles, after being sintered at 600 °C, were rigorously characterized to confirm their structural, morphological, and chemical properties. Structural analysis using X-ray diffraction confirmed the formation of a single-phase cubic spinel structure, exhibiting a small crystallite size of 13.32 nm. Further characterization via FTIR validated the formation of metal-oxygen vibrational modes. The surface chemistry was analysed using X-ray photoelectron spectroscopy (XPS), confirming the elemental composition and oxidation states. The material shows excellent colloidal stability, with a Zeta potential of −24.79 mV in suspension. Morphological analysis revealed that the nanoparticles are prone to mild agglomeration, which is attributed to their intrinsic magnetic interactions. Crucially, the material's potential for biomedical applications was assessed using the MTT cytotoxicity assay against normal L929 fibroblast cells. The results indicated high cell viability even at elevated concentrations, yielding an IC₅₀ of 289.89 μg/mL. These favorable properties—nanoscale size, excellent stability, and low toxicity—confirm that the green-synthesized Ni-Co ferrite is a promising candidate for applications such as targeted drug delivery and bio-separation.