Influence of age on the free-radical scavenging ability of CeO2 and Au/CeO 2 nanoparticles
2015
Anandkumar, M. | Ramamurthy, C. H. | Tirunāvukkaracu, Ci. | Surēṣbābu, Ke.
Cerium oxide (CeO₂) nanoparticles have been demonstrated as a potential free-radical scavenger. In the present work, gold (Au) nanoparticles were impregnated by deposition precipitation method on the surface of the combustion synthesized 13-nm CeO₂nanoparticles in order to enhance the free-radical scavenging properties of Au-supported CeO₂nanoparticles (Au/CeO₂). Raman spectroscopic calculation for CeO₂and Au/CeO₂showed an oxygen vacancy concentration of 1.22 × 10²¹and 0.80 × 10²¹ cm⁻³, respectively. The dose- and time-dependent free-radical quenching efficacy of CeO₂and Au/CeO₂nanoparticles was evaluated against hydroxyl, superoxide and nitric oxide using in vitro method. CeO₂and Au/CeO₂nanoparticles exhibited efficient scavenging of hydroxyl and superoxide radicals, but the activity was found to be low against nitric oxide radicals. Both the nanoparticles exhibited a concentration-dependent free-radical scavenging in the range of 0.01–0.0001 μM and showed a saturation behaviour above 0.1 μM. Nanoparticle solution aged for 1, 7, 14 and 28 days displayed a lower superoxide and hydroxyl radicals scavenging activity compared to freshly prepared nanoparticle solution while nitric oxide exhibited the opposite behaviour. In comparison, Au/CeO₂showed better radical scavenging activity at lower concentrations than that of CeO₂. The observed radical scavenging property can be attributed to the agglomeration as well as changes in surface oxygen vacancy concentration which are important in designing therapeutic agent for oxidative stress complications.
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