Agriculture Reference
In-Depth Information
cations, it is essential that nanoparticles should pass cell plasma membranes either
by endocytosis (Onelly et al.
2008
) or by direct penetration to reach target cellular
compartments. Onelly et al. (
2008
) reported the internalization of gold nanopar-
ticles using tobacco protoplasts. In their report, they showed the penetration of gold
nanoparticles into the protoplasts by endocytosis linking to different pathways upon
their charge.Therefore, endocytosis appears as a reasonable way for internaliza-
tion of nanoparticles. A recent report deals with penetration of gold nanoparticles
through lipid membranes bypassing endocytosis (Lin et al.
2010
). Their mean force
calculations showed a significant gain of energy upon adhesion and penetration. In
the case of penetration, it was found that defective areas were induced across the
entire surface of the upper leaflet of the bilayer and a hydrophilic pore that trans-
ports water molecule was formed with its surrounding lipids highly disordered. It
was also found that the increase in charge density of gold nanoparticles increased
the level of penetration and membrane disruption. These findings suggest a way of
controlling the gold nanoparticles-cell interactions by manipulating surface charge
densities of gold nanoparticles to achieve designated goal in their biological appli-
cations, such as a delivery agent.
5.3.2 PalladiumNanoparticles
Since the geogenic background, a significantly lower concentration of palladium
(Pd) than the concentration of other non-essential toxic elements such as mercury,
lead or cadmium, Pd may not yet have affected biological systems. Earlier studies
(Battke et al.
2008
; Jo et al.
2009
) showed a higher mobility and uptake rates of
Pd in soil than platinum, e.g., in grass samples from roadsides. Battke et al. (
2008
)
studied the uptake of Pd in barley and behavior of Pd nanoparticles in nutrient
solutions used to grow plants, in order to develop a model of Pd exposure of plant
systems. Their results showed that smaller and larger Pd particles were compara-
tively assessed and the Pd uptake, via the roots, depends on its particle diameter. Pd
nanoparticles of smaller diameter cause significant effects on leaf length growth.
As the concentration of Pd increased in the nutrient solution, leaf length decreased
significantly with the increased variability of leaf lengths. Moreover, with increas-
ing Pd concentration in the nutrient solution, leaves become rigid and slightly con-
voluted.
5.3.3 Silver Nanoparticles
Owing to their several antimicrobial functions, silver nanoparticles have been wide-
ly used to control various phytopathogens (Park et al.
2006
; Min et al.
2009
; Kim
et al.
2009
; Stampoulis et al.
2009
; Arshi et al.
2011c
). Harris et al. (
2008
) studied
the uptake limits and the distribution of silver nanoparticles in
Brassica juncea
and
Medicago sativa
. They observed that
Medicago sativa
showed an increase in metal
uptake with a corresponding increase in the substrate of metal concentration and
exposure time as compared with
Brassica juncea
. Study of hydroponic solution
