Eco-friendly synthesis of magnetic ZnO/Fe3O4 nanocomposites: Structural, morphological, antimicrobial, and anticancer evaluation

Abstract

The synthesis of nanomaterials has traditionally relied on physical and chemical methods, which, while initially effective, are often expensive and environmentally detrimental. In contrast, biological approaches utilizing natural agents such as plant extracts, enzymes, and microorganisms offer more sustainable and eco-friendly alternatives. In this study, bio-synthesized ZnO/Fe₃O₄ nanocomposites (NCs) were prepared via a chemical precipitation method, using camel urine as a natural stabilizing and capping agent. The synthesized NCs were comprehensively characterized using SEM, EDX, TEM, XRD, UV–Vis spectroscopy, FTIR, and TGA. Transmission electron microscopy revealed an average particle size of 7.41 nm, while XRD analysis confirmed the polycrystalline nature of the ZnO/Fe₃O₄ NCs. UV–Vis analysis indicated an energy band gap of 2.21 eV. FTIR spectra identified functional groups associated with ZnO/Fe₃O₄, and TGA demonstrated thermal stability up to 940 °C. The nanocomposites exhibited significant anticancer and antibacterial activities in a concentration-dependent manner. MTT assays against HCT116 colorectal cancer cells showed a reduction in cell viability from approximately 80 % at low concentrations to about 43 % at 100 μg/mL, indicating strong dose-dependent cytotoxicity. Antibacterial tests revealed higher efficacy against Gram-negative bacteria (E. coli, Pseudomonas sp.) than Gram-positive strains (S. aureus), with no observable activity against MRSA. Notably, at a concentration of 15 mg, inhibition zones reached 0.9 mm for Pseudomonas sp. and 1.4 mm for E. coli, whereas significantly smaller zones were observed at lower concentrations. These findings highlight the potential of ZnO/Fe₃O₄ NCs for biomedical applications, particularly as antibacterial coatings or anticancer agents. To the best of our knowledge, this is the first report on the synthesis of ZnO/Fe₃O₄ NCs using camel urine and their evaluation against colorectal cancer cells, representing a novel and sustainable approach in nanomedicine.