Effect of TiO2−x nanoparticle defect structure on hydroxyl radical scavenging activity under X-ray irradiation

Two types of titanium oxide nanoparticles (TiO 2-x NPs) with the same size (5.0 ± 0.6 nm), but different Ti 3+ (Ti 2+ )/Ti 4+ ratios in their crystal lattice were synthesized by the hydrolysis of titanium alkoxide varying the nitric acid content in the hydrolysis mixture. Electron donating properties and scavenging activity of both types of TiO 2-x NPs against hydroxyl radicals (·OH) formed during X-ray irradiation have been studied. It has been revealed that ·OH scavenging properties are directly related to the Ti 3+ (Ti 2+ )/Ti 4+ ratio and are higher for the sample with a higher Ti 3+ (Ti 2+ ) content. The efficiency of ·OH scavenging in synthesized TiO 2-x NPs is close to that observed for well-known antioxidant CeO 2-x NPs with the same size suggesting TiO 2-x NPs to be effective as an antioxidant in living cells as well. • Using sol-gel route TiO 2-x NPs with different Ti 3+ (Ti 2+ )/Ti 4+ ratio were obtained • Ti 3+ (Ti 2+ )/Ti 4+ ratio in TiO 2-x NPs depends on the content of peptizing agent • Content of Ti 3+ (Ti 2+ ) ions in TiO 2-x determines the efficiency of ·OH scavenging