Size-dependent Effect of CeO2 Nanoparticles on ROS Generation in Red Blood Cells

To assess reactive oxygen species (ROS) production-stimulating properties of CeO
2
nanoparticles in red blood cells. Erythrocyte suspensions prepared from intact blood samples incubated with CeO
2
nanoparticles (0-10-20-40-100-200 mg/L) were stained with 2‘,7’-dichlorodihydrofluorescein diacetate (H2DCFDA) to determine intracellular ROS levels. The ROS concentrations inside the erythrocytes were judged by dichrlorofluorescein (DCF) fluorescence acquired using BD FACS Canto™ II flow cytometer (Becton Dickinson, USA). At concentrations of 100 mg/L and below, smaller (2 nm) and larger (10 nm) CeO
2
nanoparticles had no impact on ROS production. The highest used concentrations (200 mg/L) promoted ROS overproduction only in case of small-sized nanoparticles. Our observations show that nanoceria-induced ROS generation in erythrocytes depends on nanoparticle size. This study confirms that CeO
2
-associated toxicity is mediated by excess ROS generation and oxidative stress.