Organic Biomass Mediated‐Cerium Oxide Nanoparticles for Multifunctional Activity: Anticancer MCF‐7 Breast Cancer Cells, Antibacterial, Antioxidant, and Dye Degradation

Abstract This study presents the green synthesis of cerium oxide nanoparticles (CeO₂ NPs) using Albizia julibrissin flower extract, offering an eco‐friendly and cost‐effective approach to nanoparticle fabrication. The synthesized CeO₂ NPs were characterized using UV–vis spectroscopy, which revealed a characteristic absorption peak at 310 nm, XRD confirming a cubic fluorite structure with an average crystallite size of 30 nm, and SEM/TEM showing a spherical morphology with particle sizes ranging from 10–25 nm. The nanoparticles exhibited potent antibacterial activity, with inhibition zones of 17.6 ± 0.8 mm against Escherichia coli and 15.2 ± 0.6 mm against Staphylococcus aureus , demonstrating their broad‐spectrum antimicrobial efficacy. The antioxidant potential, evaluated via DPPH assay, showed a radical scavenging activity of 78.4% at 100 µg/mL, comparable to standard antioxidants. The cytotoxicity study on MCF‐7 breast cancer cells revealed an IC₅₀ value of 48.6 µg/mL, indicating significant anticancer activity. Furthermore, the photocatalytic degradation of methylene blue dye under visible light illumination achieved a 92.3% degradation efficiency within 120 min, highlighting the environmental remediation potential of CeO₂ NPs. These findings establish plant‐mediated CeO₂ NPs as promising candidates for biomedical and environmental applications.