Size-dependent hydroxyl radicals generation induced by SiO2 ultra-fine particles:The role of surface iron

• 来源期刊: 中国科学B辑(英文版)
• 年，卷（期）: 2009,（7）
• 页码范围: 1033-1041
• 页数: 9页
• 语种: 英文
• DOI: 10.1007/s11426-009-0141-9

摘要

Oxidative stress and hydroxyl radicals (.OH) play important roles in adverse health effects caused by inhalable ambient air particles (PM10).The ultra-fine fraction of PM10 has been hypothesized as one of the critical contributors to .OH generation.Both in vivo and in vitro studies have shown that ultra-fine particles (UFPs) or nano-particles generate more .OH than larger particles with identical mass and composition.Both the surface area and surface-adsorbed redox-active metals have been suggested as factors to determine the oxidative capacity of UFPs.In this study,the .OH-generating capability of different sizes of SiO2 particles was investigated in order to determine which factor influences particle-induced .OH generation.The amount of .OH generated in both acellular and cellular systems was quantified using a capillary electrophoresis method following exposure to SiO2 particles with diameters of 14,100,and 500 nm.The amount of .OH was strongly dependent on particle size,and a significant enhancement was observed only with 14 nm particles.Further studies indicated a close association between .OH and iron ion concentration (R2=0.812,p＜0.01).Washed particles,with their surface iron being removed,did not generate .OH.The iron-containing leachate from these washings was able to enhance .OH production as untreated particles did.Therefore,the presence of adsorbed iron on the surface of the SiO2 particles is presented as a possible mechanism of UPFs-induced .OH generation.The SiO2 acted as an inert substrate,and the surface of ultra-fine SiO2 particles acted as a carrier for iron.