Defect-engineered Gd-doped CeO₂ nanoparticles: structural insights and cytotoxic response in HEK-293 cells

Costa M.C.; Garcia F.G.; Flores E.; Acero G.; Ramirez M.A.; Simões A.Z. · Inorganic Chemistry Communications (2026) · DOI: 10.1016/j.inoche.2026.117174

Resumen

In this work, we report the synthesis, structural characterization, and cytotoxicity assessment of gadolinium-doped CeO₂ nanoparticles (CeO₂:Gd NPs) using a microwave-assisted hydrothermal (MAH) method. Structural and physicochemical properties were investigated by X-ray diffraction (XRD), Raman spectroscopy, UV–visible spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and electron paramagnetic resonance (EPR). All samples exhibited a cubic fluorite structure with crystallite sizes ranging from 1.2 to 1.7 nm. TEM analysis revealed quasi-spherical nanoparticles with sizes between 2.5 and 6.2 nm. Gd incorporation induced lattice expansion, increased defect density, and promoted oxygen vacancy formation, as confirmed by XPS and EPR analyses. Optical characterization demonstrated that the band gap energy decreased from 3.10 eV to 2.90 eV with increasing Gd content, reaching its minimum value at a doping level of 8%. Cytotoxicity was evaluated in HEK-293 cells, showing cell viability above 90% after 24 and 48 h exposure, indicating low toxicity under the tested conditions. The results suggest that Gd doping modifies the defect structure and physicochemical properties of CeO₂ nanoparticles, which may contribute to the observed differences in biological response. Specifically, the substitution of Ce4+ by Gd3+ promotes the formation of oxygen vacancies and alters the Ce3+/Ce4+ ratio, affecting the surface chemistry and redox behavior of the nanoparticles. These structural changes may influence their interaction with cells and, consequently, their biological activity.

Instituciones: Universidad Nacional Jorge Basadre Grohmann