Environmental Engineering Reference
In-Depth Information
applied at 24 h at er inoculation. h e in vitro evaluations of silver indi-
cated that both silver ions and nanoparticles inl uence colony formation of
spores and disease progress of plant-pathogenic fungi. In plants, ei cacy of
silver ions and nanoparticles is much greater with preventative application,
which may promote the direct contact of silver with spores and germ tubes,
and inhibit their viability [73].
Silver nanoparticles have an inhibitory ef ect against powdery mildew
on cucumbers and pumpkins. Powdery mildew is one of the most devas-
tating diseases in cucurbits. Crop yield can decline as the disease sever-
ity increases. A study evaluated the ef ect of silver nanoparticles against
powdery mildew under dif erent cultivation conditions in vitro and in
vivo . Silver nanoparticles (WA-CV-WA13B) at various concentrations
were applied before and at er disease outbreak in plants to determine
antifungal activities. In the i eld tests, the application of 100 ppm silver
nanoparticles showed the highest inhibition rate for both before and at er
the outbreak of disease on cucumbers and pumpkins. Also, the applica-
tion of 100 ppm silver nanoparticles showed maximum inhibition for
the growth of fungal hyphae and conidial germination in  in vivo   tests.
Scanning electron microscope results indicated that the silver nanopar-
ticles caused detrimental ef ects on both mycelial growth and conidial
germination.
12.8
Mechanism of Action of Nanoparticle
inside the Body
h e fact that nanoparticles exist in the same size domain as proteins
makes nanomaterials suitable for biotagging or labeling. However, size is
just one of many characteristics of nanoparticles that in itself are rarely
sui cient if one is to use nanoparticles as biological tags. In order to inter-
act with a biological target, a biological or molecular coating or layer act-
ing as a bioinorganic interface should be attached to the nanoparticle.
Examples of biological coatings may include antibodies, biopolymers like
collagen, or monolayers of small molecules that make the nanoparticles
biocompatible [47].
Nanoparticle usually forms the core of nanobiomaterial. It can be
used as a convenient surface for molecular assembly, and may be com-
posed of inorganic or polymeric materials. It can also be in the form of
nanovesicle surrounded by a membrane or a layer. h e shape is more
ot en spherical but cylindrical, plate-like and other shapes are possible.
h e size and size distribution might be important in some cases, for
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