Agriculture Reference
In-Depth Information
consumer products, pharmaceuticals, cosmetics, transportation, energy and agricul-
ture (Nowack et al.
2007
; Roco et al.
2003
). The properties of engineered nanoma-
terials are essentially important due to their aggregation behavior and mobility in
aquatic and terrestrial systems and also for their interaction with algae, plants and
fungi (Enrique et al.
2008
). Engineered nanomaterials can be categorized as:
• Carbon-based nanomaterials
• Metal-based nanomaterials
• Dendrimers
• Composites
2.3.1 Carbon-Based Nanomaterials
These types of nanomaterials mainly consist of carbon having the most common
form of hollow spheres, ellipsoids, or tubes. Spherical and ellipsoidal carbon nano-
materials are referred to as fullerenes, while cylindrical ones are called nanotubes
such as single-walled carbon nanotube (SWCNT) and multi-walled carbon nano-
tubes (MWCNT). These materials have various potential applications, such as
improved films and coatings, stronger and lighter materials, and applications in
electronics, agriculture and food (Remya et al.
2010
). Recently, it was found that
fullerenes may act as antioxidants, preventing lipid peroxidation induced by super
oxide and hydroxyl radicals (Wang et al.
1999
).
2.3.2 Metal-Based Nanomaterials
Metal-based nanomaterials have received considerable attention in science and
technology in the last decade. These include quantum dots, gold, silver, palladium
and metal oxides (TiO
2
and ZnO) nanomaterials. There is a huge scope for apply-
ing nanomaterials to plants for agricultural use (Liu et al.
2002
; Pavel et al.
1999
;
Pavel et al.
2005
; Joseph et al.
2006
). TiO
2
nanoparticles have been found to in-
duce spinach seed germination of aged seeds and its vigor (Zheng et al.
2005
). It
was also observed that the presence of TiO
2
nanoparticles increases the dry weight,
chlorophyll synthesis, and metabolism in photosynthetic organisms. Due to the an-
timicrobial properties of engineered nanomaterials, the strength and resistance of
plants to stress can be increased. Gene transfer by bombardment of DNA-absorbed
gold particles has been successfully used to generate transgenic plants in a species-
independent manner (Christou et al.
1988
).
2.3.3 Dendrimers
Dendrimers are nanosized polymers composed of branched units having the capa-
bility to be customized to perform a specific chemical function. The surface of a
