Oxidative Damage Evaluation in Erythrocytes

Following incubation of erythrocytes with SiNPs or normal saline (control), the mixture was centrifuged, and the resulting supernatants were subjected to oxidative damage/stress marker assays including LPO, CAT, SOD, and GSH. NADPH-dependent erythrocyte membrane LPO was measured as a thiobarbituric acid reactive substance using malondialdehyde as standard (Sigma-Aldrich Fine Chemicals, St. Louis, MO, USA. GSH concentration (Sigma Chemicals, St. Louis, MO, USA), and CAT activity (Activity kit, Cayman chemicals, Ann Abror, MI, USA) were analyzed spectrophotometrically according to methods described by the manufacturers. SOD activity was measured as the conversion of nitroblue tetrazolium (NBT) to NBT-diformazan according to the vendor’s protocol (R&D Systems). The extent of reduction in the appearance of NBT-formazan was used as a measure of SOD activity present in the plasma.