title: Effects of functionalized and nonfunctionalized single-walled carbon nanotubes on root elongation of select crop species.
abstract: 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.
authors.affiliation: The Institute of Environmental and Human Health, Department of Environmental Toxicology, Texas Tech University, Lubbock, Texas 79409, USA. jaclyn.canas@tiehh.ttu.edu
authors.forename: Jaclyn E
authors.initials: JE
authors.lastname: Cañas
authors.forename: Monique
authors.initials: M
authors.lastname: Long
authors.forename: Shawna
authors.initials: S
authors.lastname: Nations
authors.forename: Rodica
authors.initials: R
authors.lastname: Vadan
authors.forename: Lenore
authors.initials: L
authors.lastname: Dai
authors.forename: Mingxiang
authors.initials: M
authors.lastname: Luo
authors.forename: Ramya
authors.initials: R
authors.lastname: Ambikapathi
authors.forename: E Henry
authors.initials: EH
authors.lastname: Lee
authors.forename: David
authors.initials: D
authors.lastname: Olszyk
mesh_terms: D002244:Carbon / Q000633:toxicity*; D008855:Microscopy, Electron, Scanning; D043942:Nanotubes / Q000633:toxicity*; D010865:Pilot Projects; D018517:Plant Roots / Q000187:drug effects* / Q000254:growth & development* / Q000648:ultrastructure; D012044:Regression Analysis; D036226:Seedlings / Q000187:drug effects / Q000502:physiology; D012639:Seeds / Q000737:chemistry; D013535:Suspensions
chemical_list: D013535:Suspensions; D002244:Carbon