Bio-Inspired Ce–TiO2 Nanostructures as Triple-Functional Platforms for Environmental and Biomedical Applications

Cerium-doped titanium dioxide nanoparticles (Ce-TiO2 NPs) were developed using a sustainable sol-gel technique, utilizing Annona muricata leaf extract as a natural reducing and stabilizing agent. Comprehensive characterization techniques were employed to elucidate their structural, optical, antimicrobial, and anticancer functionalities. X-Ray diffraction (XRD) and transmission electron microscopy (TEM) analyses confirmed the successful incorporation of cerium ions into the TiO2 lattice, which favored the formation of a higher rutile phase content, refined crystallite sizes, and improved particle morphology. Elemental mapping through energy-dispersive X-ray spectroscopy (EDS) validated the effective dispersion of Ce dopants. UV-Visible spectroscopy revealed a conspicuous bandgap narrowing and enhanced visible light absorption attributable to cerium incorporation. The nanoparticles exhibited potent antimicrobial activity against various pathogenic bacteria and fungi. Photocatalytic experiments demonstrated that Ce-TiO2 NPs achieved 94% degradation of methylene blue dye within 80 min under sunlight irradiation. Moreover, cytotoxicity assays using MDA-MB-231 human breast cancer cells indicated a significant, dose-dependent decrease in cell viability. These findings highlight the enhanced therapeutic efficacy conferred by cerium doping, underscoring its potential for visible-light-driven photodynamic cancer therapies.