Investigation of the anticancer, antibacterial, and photocatalytic properties of CeO ₂ and Cu-CeO ₂ nanoparticles synthesized by a green method

Cerium oxide (CeO₂) and copper-doped cerium oxide (Cu-CeO₂) nanoparticles were synthesized using Psidium guajava leaf extract as a reducing and stabilizing agent. Characterization techniques included X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) analysis. XRD analysis confirmed the crystalline nature of the CeO₂ nanoparticles, revealing a cubic fluorite structure. The incorporation of Cu ions into the CeO₂ lattice was evidenced by shifts in the diffraction peaks. SEM images showed spherical nanoparticles with smooth surfaces. EDX analysis confirmed the presence of copper, validating the success of the doping process. UV-Vis spectroscopy displayed absorption peaks at 306 and 316 nm, indicative of the photocatalytic activity of the nanoparticles. The synthesized nanoparticles exhibited antimicrobial activity against three bacterial strains, with a notable inhibitory effect on Klebsiella pneumoniae. Additionally, their anticancer potential was evaluated on two cell lines: HCT116 (colorectal cancer) and L929 (fibrosarcoma). Notably, pure CeO₂ nanoparticles exhibited lower toxicity in both cases. These findings suggest promising biomedical applications for the synthesized nanoparticles.