Agriculture Reference
In-Depth Information
9.3.7.2
Iron Oxide Nanoparticles
Many studies on iron oxide nanoparticles have been published as important mate-
rials for several biomedical applications, such as nuclear magnetic resonance
imaging, hyperthermia, and drug delivery systems (Hadadd and Seabra
2012
).
Magnetic nanoparticles can also find important applications on plants. Small size
carbon-coated magnetic iron oxide nanoparticles were shown to penetrate into plant
tissues, and the bioferrofluid was able to spread out through the vascular system to
plant after application of magnetic gradients. However, particles over 50 nm of
diameter were not detected inside plant tissues (e.g., barrier imposed by cell walls
and waxes) indicating that absorption of these nanoparticles depends on particle
size (Gonzalez-Melendi et al.
2008
). In some cases, this process occurred in plant
tissues (e.g.,
Cucurbita maxima
) grown in an aqueous medium containing the
nanoparticles (Zhu et al.
2008
). Then, plants have different responses to the same
nanoparticles (Monica and Cremonini
2009
).
Racuciu and Creanga (
2007
) using magnetic nanoparticles coated with
tetramethyl ammonium hydroxide on the growth of
Zea mays
plant, in early
ontogenetic stages, showed that these nanoparticles not only exert a chemical effect
but also a magnetic influence on the enzymatic structures involved in different
stages of photosynthesis. In this report, it was found that the growth was dose
dependent; low concentration stimulated growth, while high one inhibited growth.
Phytotoxicities of metal oxide nanoparticles, magnetite, aluminum oxide, silicone
dioxide, and zinc oxide, were evaluated on the development of
Arabidopsis
thaliana
. The most toxic was ZnO nanoparticles compared to magnetite, in seed
germinations, root elongations, and number of leaves (Chang et al.
2010
).
NO-releasing superparamagnetic iron oxide nanoparticles were able to sponta-
neously release controllable and therapeutic amounts of NO (Molina et al.
2013
).
This system might find important applications in plants and thus needs to be
explored in more detail.
9.3.7.3 Silver Nanoparticles
Silver nanoparticles exert antimicrobial activities (Dur´n et al.
2010
; Holtz
et al.
2010
). Several papers reported the toxic effects of silver nanoparticles in
plants. Toxic effects of silver nanoparticles on the algae
Chlamydomonas
reinhardtii
have been reported (Navarro et al.
2008
). Growth of
Cucurbita pepo
was also found to be inhibited by these nanoparticles (Stampoulis et al.
2009
). The
phytotoxicity of silver nanoparticles depends on the plant. A more toxic effect on
the plant (
Lemna minor
) was observed by increasing exposure time with
nanoparticles, and in general, silver nanoparticles were found to be more phytotoxic
in comparison with bulk silver (Eva et al.
2011
). However, silver nanoparticles
were reported to be less phytotoxic to
C. pepo
, compared to bulk silver (Musante
and White
2012
). Ultrahigh concentrations of silver nanoparticles (1 g/L), with
