*2.1. Nanoparticles Characterization*

The *n*CeO2 with an average particle size of 25 nm and 50 nm, respectively, were purchased from Sigma-Aldrich (St. Louis, MO, USA). *n*CeO2 has a density of 7.13 g mL−<sup>1</sup> at 25 ◦C and 99.95% purity (81.25% of Ce).

The cerium oxide nanoparticles were suspended in deionized water and sonicated in a water bath for 60 min with a sonication power of 180 watts. The suspensions were characterized for Z–average size and hydrodynamic diameter (Hd), whose distributions were measured by dynamic light scattering (DLS) on a Zetasizer Nano ZS (Malvern Ltd., Worcestershire, UK) and relative polydispersity index (PDI). ζ—potentials at pH 7.0 were quantified by laser Doppler velocimetry as the electrophoretic mobility, using a disposable electrophoretic cell (DTS1061, Malvern Ltd., Worcestershire, UK). The size and average shape were measured with transmission electron microscopy (TEM, FEI Tecnai F20, FEI Company, Eindhoven, The Netherlands).
