In this work, ZnO/Fe₃O₄ nanocomposites were synthesized via a green route using aqueous extract of Murraya koenigii fruit pods and Cissus quadrangularis stem extract as a reducing and stabilizing agent. The phytochemicals, particularly alkaloids and flavonoids, facilitated nanoparticle nucleation and controlled growth. The nanocomposites were characterized using XRD, Raman spectroscopy, FTIR, VSM, and zeta potential, confirming the coexistence of wurtzite ZnO and spinel Fe₃O₄ phases with nanoscale crystallite sizes (~20 nm). Biological activities were systematically evaluated: significant antifungal activity against Candida albicans and antibacterial action against Pseudomonas aeruginosa were observed, attributed to ROS generation and membrane disruption. Antioxidant properties, assessed via the DPPH assay, demonstrated moderate radical scavenging activity (IC₅₀ values higher than ascorbic acid), suggesting indirect antioxidant relevance through ROS modulation. MTT assays against A549 and MCF-7 cell lines revealed dose-dependent cytotoxicity, mediated by ROS generation and mitochondrial dysfunction, confirming the anticancer potential of the nanocomposites. Photocatalytic degradation of Alizarin dye under visible light followed pseudo-first-order kinetics (Langmuir-Hinshelwood model), achieving >90% degradation within 80 min and showing good recyclability. The results indicate that ZnO/Fe₃O₄ nanocomposites are promising multifunctional materials for biomedical and environmental applications, particularly in water pollution remediation.

Keywords: ZnO/Fe₃O₄ nanocomposite, green synthesis, antimicrobial, anticancer, photocatalysis, water purification