Geoscience Reference
In-Depth Information
Effect of size on melting point of
gold nanoparticles
Fluorescence of semiconductor nanocrystals
Decreasing crystal size
1100
1000
900
800
700
600
500
400
300
200
10
0
0123456
Particle radius (nm)
78910 11
By controlling nanoscale (1) composition, (2) size and (3) shape,
we can create new materials with new properties → new technologies
FIGURe 5.3
(
See colour insert.
) The effect of particle size on chemical and physi-
cal properties of nanoparticles.
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
