Biomedical Engineering Reference
In-Depth Information
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Carbon nanotubes
FIGURE 26.5
(See. color. insert.). Tomato. seedlings. grown. with. and. without. ~40. mg/L. MWNT. additive.. (Reprinted. from.
Khodakovskaya.et.al.. ACS Nano 3(10).3221.(2009)..With.permission.of.the.American.Chemical.Society.)
inside.seeds,.a.process.that.can.affect.seed.germination.and.enhance.the.growth.of.tomato.
seedlings,.as.shown.in.Figure 26.5. 34
The.effects.of.functionalized.and.nonfunctionalized.single-walled.carbon.nanotubes.on.
root.elongation.were.studied.in.several.select.crop.species.that.are.generally.used.in.phyto-
toxicity.testing.(cabbage,.carrot,.cucumber,.lettuce,.onion,.and.tomato). 35 .Nanotubes.were.
functionalized. with. poly-3-aminobenzenesulfonic. acid. and. compared. to. nonfunctional-
ized.controls..Root.growth.was.measured.at.0,.24,.and.48.h.following.exposure.by.scanning.
electron.microscopy..In.general,.nonfunctionalized.carbon.nanotubes.affected.root.length.
more. than. functionalized. nanotubes.. Nonfunctionalized. nanotubes. inhibited. root. elon-
gation. 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.. The. effects. observed. following. exposure. to. carbon. nanotubes.
tended.to.be.more.pronounced.at.24.than.at.48.h..Microscopy.images.showed.the.presence.
of.nanotube.sheets.on.the.root.surfaces,.but.no.visible.uptake.by.the.cells..Canas.reported.
the.effect.of.MWNTS.on.root.elongation. 35
26.4.4 Nanoparticles as Protective Systems
Hong.and.co-workers.examined.protective.effects.of.nanoparticles.on.the.photosynthetic.
apparatus. which. could. lead. to. a. useful. application. 36 . Nano-TiO 2 -treated. chloroplasts. of.
spinach. were. irradiated,. and. results. showed. that. spinach. treated. with. 0.25%. nano-TiO 2 .
appeared.to.be.protected.from.light-induced.redox.damage..The.nano-TiO 2 .treatment.sig-
niicantly.increased.the.activities.of.superoxide.dismutase,.catalase,.and.peroxidase..The.
authors.measured.decreased.accumulation.of.reactive.oxygen.radicals.and.lower.levels.of.
malondialdehyde,.a.marker.for.membrane.redox.damage.
26.4.5 Nanoparticles as Tools for Plant Biology
26.4.5.1   The Gene Gun
A. common. application. of. nano-. and. micron-sized. gold. or. tungsten. particles. is. widely.
used.in.plant.genetic.modiication:.the.gene.gun. 37,38 .This.process,.called.biolistics,.involves.
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