Effects of functionalized and nonfunctionalized single-walled carbon nanotubes on root elongation of select crop species

• Published in: Environmental toxicology and chemistry 2008-09, Vol.27 (9), p.1922-1931
• Main Authors: Canas, Jaclyn E, Long, Monique, Nations, Shawna, Vadan, Rodica, Dai, Lenore, Luo, Mingxiang, Ambikapathi, Ramya, Lee, E. Henry, Olszyk, David
• Format: Article
• Language: English
• Subjects: Agricultural chemicals; Agricultural production; Allium cepa; Animals; Brassica; Brassica oleracea var. capitata; cabbage; Carbon; Carbon - toxicity; Carbon nanotubes; Carrots; Copyrights; Crops; Cucumbers; Cucumis sativus; Daucus; Daucus carota; Documents; Elongation; Environmental protection; Human exposure; Lactuca sativa; Lettuce; Lettuces; Lycopersicon esculentum; Manufactured nanomaterials; Microscopy; Microscopy, Electron, Scanning; Nanoparticles; Nanotechnology; Nanotubes; Nanotubes - toxicity; Nations; Onions; Phytotoxicity; Pilot Projects; Plant growth; Plant Roots - drug effects; Plant Roots - growth & development; Plant Roots - ultrastructure; Polycyclic aromatic hydrocarbons; Presses; Regression Analysis; Root elongation; root growth; Roots; scanning electron microscopy; Seedlings - drug effects; Seedlings - physiology; Seeds - chemistry; Single wall carbon nanotubes; Solanum lycopersicum var. lycopersicum; Studies; Suspensions; Tomatoes; Toxicity; Uptakes; Vegetables; Zinc oxides
• ISSN: 0730-7268; 1552-8618
• DOI: 10.1897/08-117.1

Single-walled carbon nanotubes have many potential beneficial uses, with additional applications constantly being investigated. Their unique properties, however, create a potential concern regarding toxicity, not only in humans and animals but also in plants. To help develop protocols to determine the effects of nanotubes on plants, we conducted a pilot study on the effects of functionalized and nonfunctionalized single-walled carbon nanotubes on root elongation of six crop species (cabbage, carrot, cucumber, lettuce, onion, and tomato) routinely used in phytotoxicity testing. Nanotubes were functionalized with poly-3-aminobenzenesulfonic acid. Root growth was measured at 0, 24, and 48 h following exposure. Scanning-electron microscopy was used to evaluate potential uptake of carbon nanotubes and to observe the interaction of nanotubes with the root surface. In general, nonfunctionalized carbon nanotubes affected root length more than functionalized nanotubes. Nonfunctionalized nanotubes inhibited root elongation in tomato and enhanced root elongation in onion and cucumber. Functionalized nanotubes inhibited root elongation in lettuce. Cabbage and carrots were not affected by either form of nanotubes. Effects observed following exposure to carbon nanotubes tended to be more pronounced at 24 h than at 48 h. Microscopy images showed the presence of nanotube sheets on the root surfaces, but no visible uptake of nanotubes was observed.