Iron Bioavailability and Redox Activity in Diverse Carbon Nanotube Samples

详细信息    查看全文

• 作者：Lin Guo ; Daniel G. Morris ; Xinyuan Liu ; Charles Vaslet ; Robert H. Hurt ; Agnes B. Kane
• 刊名：Chemistry of Materials
• 出版年：2007
• 出版时间：July 10, 2007
• 年：2007
• 卷：19
• 期：14
• 页码：3472 - 3478
• 全文大小：618K
• 年卷期：v.19,no.14(July 10, 2007)
• ISSN：1520-5002

文摘

The ultimate success of many nanotechnologies will depend on our ability to understand and managenanomaterial health risks. Carbon nanotubes are now primarily fabricated by catalytic routes and typicallycontain significant quantities of transition metal catalyst residues. Iron-catalyzed free-radical generationhas been hypothesized to contribute to oxidative stress and toxicity upon exposure to ambient particulate,amphibole asbestos fibers, and single-wall carbon nanotubes. A key issue surrounding nanotube iron isbioavailability, which has not been systematically characterized, but is widely thought to be low on thebasis of electron microscope observations of metal encapsulation by carbon shells. Here, we validate andapply simple acellular assays to show that toxicologically significant amounts of iron can be mobilizedfrom a diverse set of commercial nanotube samples in the presence of ascorbate and the chelating agentferrozine. This mobilized iron is redox active and induces single-strand breaks in plasmid DNA in thepresence of ascorbate. Iron bioavailability varies greatly from sample to sample and cannot be predictedfrom total iron content. Iron bioavailability is not fully suppressed by vendor "purification" and is sensitiveto partial oxidation, mechanical stress, sample age, and intentional chelation. The results suggest practicalmaterials chemistry approaches for anticipating and managing bioavailable iron to minimize carbonnanotube toxicity.