Non‐UV‐Induced Radical Reactions at the Surface of TiO2 Nanoparticles That May Trigger Toxic Responses

摘要: Kept in the dark: The non-photocatalytic generation of free radicals from fine and ultrafine TiO(2) particles has been studied by means a spin-trapping/ESR spectroscopy technique (see figure). amount kind generated depends on crystalline structure, but not particle dimensions.Titania is generally considered to be an inert safe material. Several studies, however, have reported that nanosized may elicit toxic effects. In some cases observed adverse effects related radicals. Although new studies mainly concern irradiated titania, role mechanisms absence UV irradiation are well known. purpose present study investigate free-radical-generation nano- micronsized anatase or rutile powders under normal laboratory illumination dark technique. This used identify nature released solution, solid-state characterise paramagnetic centres at surface participate reactions. following radical-generating considered: 1) oxygenated (HO(2) (.), O(2) (.-), HO(.)) reaction with oxygen, water H(2)O(2) 2) carbon-centred cleavage C--H bond model molecule. no were detected simply buffered (.-) HO(.), respectively, presence H(2)O(2). Both polymorphs also active bond. formation appears exposure sunlight, HO(.) occurs dark. When samples equal area tested, micron- was found react same way indicating reduction diameter does generate kinds reactive sites. data presented herein implications assessment health risk associated nanoparticles ecotoxicological impact their possible leakage into environment.