ROS evaluation for series of CNTs using ESR method and its CNT concentration effects.
Tsuruoka-S; Takeuchi-K; Koyama-K; Tristan-Lopez-F; Matsumoto-H; Saito-N; Usui-Y; Endo-M; Terrones-M; Porter-DW; Castranova-V
Toxicologist 2013 Mar; 132(1):91
Carbon nanotubes (CNTs) are becoming important materials in industries. It is a concern that CNTs may induce carcinogenic responses through pulmonary exposure. It has been recently reported that CNTs scavenge ROS, which is utilized for toxicological evaluations. Although the electron charge transfer seems the noticeable phenomena of toxicological chemical reactions, any comprehensive evaluation of ROS scavenging capabilities using a variety of CNTs has not been demonstrated well. The present work specifically investigates ROS scavenging capabilities using the series of CNTs and their derivatives: more than 15 kinds of CNTs. Those ROS scavenging properties were measured by ESR with DMPO. Highly crystallized, mechanically chopped, mechanically de-bulked, and metal doped CNTs were evaluated (Group A). Furthermore, several of commercially available CNTs (Group B) were compared with Group A. Interestingly the ROS scavenging rate was not significantly influenced by mechanical treatments, but depended on crystallization at high temperature. Very thin DWCNTs showed elimination of OH radical almost, implying existence of diameter threshold. The ratio of CNTs to DMPO influenced the scavenging rate of CNTs buy not titanium dioxide, as a higher concentration of CNTs showed the lower scavenging rate, this suggests that DMPO is partly adsorbed on the CNT surface and decreases the activity. The results suggest that the electron transfer on the CNT surface is the fundamental mechanism of ROS scavenging. Dangling bonds are not a key factor for scavenging, though. ROS is affected by CNT/DMPO ratio.
Toxicology; Nanotechnology; Lung-cancer; Cancer; Respiratory-system-disorders; Pulmonary-system-disorders; Analytical-instruments; Analytical-processes; Carcinogenicity; Temperature-effects; Oxidative-processes; Chemical-binding; Biochemical-analysis; Free-radicals
The Toxicologist. Society of Toxicology 52nd Annual Meeting and ToxExpo, March 10-14, 2013, San Antonio, Texas