S. K. Guru
5.8 Applications of nanotechnology
Nanoparticles have the ability to work at the cellular level and rearrange the atoms in the DNA of an organism for the Crop
improvement
Atoms Bottom
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Nano- particles
Bulk
Physical method Chemical method
e.g. laser ablation and ball milling e.g. reduction
FIGURe 5.2 (See colour insert.) Classical approaches for nanoparticle synthesis.
expression of the desired character, thus shortening the time- consuming conventional methods. Nanotechnology has the potential to modify the molecular constitution of the crop plants, making it suitable for cultivation under adverse conditions. Both natural and induced mutations have an important role in crop improvement. Under this background, nanotechnology creates a new dimension without the use of chemical compounds and physical mutagens such as x-ray, γ-ray and so on. In Thailand, Chiang Mai University’s Nuclear Physics Laboratory has devel- oped a new white-grained rice variety from a traditional purple- coloured rice variety called Khao Kam. The colour of the leaves and stems of Khao Kam were changed from purple to green and the grain became whitish (ETC, 2004). The principle behind such a change was that a nano-sized hole was drilled through the wall and membrane of a rice cell, to insert a nitrogen atom.
The nitrogen atom is passed through the hole and a particle beam was used to stimulate rearrangement of the DNA. This newly derived organism is designated as an atomically modified organism (AMO), because of its evolution through change at the atomic level. Further research work for crop improvement is still going on worldwide.
Gene delivery Non-viral gene-delivery systems have gained considerable attention as compared to viral systems, even though the efficacy of DNA transfection is very low in the for- mer case. Non-viral vectors have several advantages, such as they are relatively easy to prepare, less immunogenic and onco- genic and there is no viral recombination. One such example
Effect of size on melting point of gold nanoparticles
Melting point (°C)
11001000 900800 700600 500400 300200 1000
0 1 2 3 4 5 6 Particle radius (nm)
7 8 9 10 11
By controlling nanoscale (1) composition, (2) size and (3) shape, we can create new materials with new properties → new technologies
Fluorescence of semiconductor nanocrystals
Decreasing crystal size
Melting p
oint - 1064°C
FIGURe 5.3 (See colour insert.) The effect of particle size on chemical and physi- cal properties of nanoparticles.
of non-viral vectors is a functionalised nanoparticle. The func- tionalised nanoparticles have the ability to incorporate genetic materials such as plasmid DNA (deoxyribonucleic acid), RNA (ribonulceic acid) and siRNA (small interfering ribonuleic acid), but with little toxicity. This demonstrates a new era in pharma- cotherapy for delivering genes into specific tissues and cells (Jin et al., 2009).
Nanotechnology in disease diagnostics Crop productivity is greatly affected by diseases. The detection of the disease at the exact stage is essential to effectively prevent it. Viral diseases are the toughest ones to control as compared to other diseases. To prevent most of the diseases, pesticides are routinely used; this is not only associated with residual toxicity and environmental hazards but also results in crop yield loss, if applied after the appearance of the disease. Nano-based viral diagnostics include a multiplexed diagnostic kit development which plunges for the detection of the exact strain of the virus and its stage of applica- tion. Along with the detection power of these nano-based diag- nostic kits, they can also increase the speed of detection. The detection and utilisation of biomarkers for accurate indication of the stages of disease with differential protein production in both healthy and diseased states, lead to the identification of several proteins during the infection cycle. These proteins can be used as markers for that particular disease stage.
Nanotechnology in pest control With the advancement of nanotechnology, nanoparticles are now being used to produce pesticides, insecticides and insect repellants (Owolade et al., 2008). Nanoencapsulation is a process that involves the slow and efficient release of chemicals such as insecticides into a particular host plant for insect pest control. Nanoencapsulation with nanoparticles in the form of pesticides allows proper absorption of the chemical by the plants unlike large particles (Scrinis and Lyons, 2007). Release mechanisms of nanoencap- sulation are diffusion, dissolution, biodegradation and osmotic pressure at specific pH. This process is also capable of deliver- ing DNA and other desired chemicals into plant tissues for pro- tection against insect pests. The ongoing research on silkworm, Bombyx mori L. race Nistari clearly shows that nanoparticles could stimulate more production of fibroin protein that can help to produce carbon nanotubes in future (Bhattacharyya et al., 2008; Bhattacharyya, 2009). Nanoencapsulation is currently the most promising technology for protection of host plants against insect pests, but the toxicological and ecotoxicological
risks linked to this emerging technology have not been exam- ined. Research on nanoparticles and insect control should be geared towards the introduction of faster and ecofriendly pesti- cides in the future (Bhattacharyya et al., 2007). Therefore, the leading chemical companies focus especially on nanopesticides formulation for targeting the host tissue through nanoencapsu- lation. Thus, nanotechnology will surely revolutionise agricul- ture in the near future.
Nanotechnology for mitigating climate change Nanotechnology is flourishing as one of the newest approaches to combat the climate change. Under sub-optimal conditions, the potential of gold nanoparticles in alleviating the oxidative damage to Brassica juncea has already been explored (Arora et al., 2012). Besides this, they have also concluded that the gold nanoparticles improve the redox status of the plants under adverse conditions, thereby facilitating healthy survival of this crop. The significant increase in seed yield was also observed in gold nanoparticle-treated plants. Thus, nanotechnology paves the way for food security even under the unfavourable environmental conditions.
Nanoparticles for environmental remediation Nanoparticles represent a new category of environmental rem- edy technologies that provide cost-effective solutions to some of the most challenging environmental problems. Research has shown that iron nanoparticles are very effective for the trans- formation and detoxification of a wide variety of common envi- ronmental contaminants, such as chlorinated organic solvents, organo-chlorine pesticides and so on. Iron nanoparticles have a large surface area, high surface reactivity and also provide enormous flexibility for in situ applications. Catalysed and sup- ported nanoparticles have been synthesised to further enhance the speed and efficiency of remediation. Recent research has suggested that in a remediation technique, the use of iron nanoparticles has the following advantages: (1) effective for transforming a large variety of environmental contaminants, (2) cost-effective and (3) non-toxic. Recent laboratory research has largely established iron nanoparticles as effective reduc- tants and catalysts for a variety of common environmental contaminants, including chlorinated organic compounds and metal ions. Using a palladium and iron nanoparticles dose at 6.25 gL−1, all chlorinated compounds were reduced below the detectable limits (Chinnamuthu et al., 2009). Zero-valent iron (ZVI) can be used as a chemical reductant for the removal of
chlorinated and nitroaromatic compounds under anaerobic environmental conditions (O’Hara et al., 2006). Another appli- cation of nanoparticles is the sequestration of metallic ion and heavy metal from aqueous solutions (e.g. Ag, Hg, Pb, Cu, Zn, Sb, Mn, Fe, As, Ni, Al, Pt, Pd and Ru). In the presence of mag- netic ions such as iron sulphide, heavy metals precipitate onto the bacterial cell wall, making the bacteria sufficiently mag- netised for removal from the suspension by magnetic separa- tion procedure. Research has shown that certain bacteria could produce iron sulphonamide. These particles could be used for the removal of harmful agents from the surrounding environ- ment. This new method employs molecular templates to coat nanoparticles of magnetite with mesoporous silica.