1. Nanotechnology and its
applications in crop
improvement

2. Nanotechnology and its applications in crop improvement
Abstract
Nanotechnology is the Design, Fabrication and Utilization of materials, devices
and systems through control of matter on the nanometer length scale and exploitation of
novel phenomena and properties (physical, chemical, biological) at that length scale. It is
now more properly labeled as "molecular nanotechnology" (MNT) or "nano-scale
engineering”. By taking advantage of quantum-level properties, nanotechnology allows
for unprecedented control of the material world, at the nanoscale, providing the means by
which systems and materials can be built with exact specifications and characteristics,
allowing materials to be lighter, stronger, smarter, cheaper, cleaner and more precise.
Nanotechnology has the potential to advance agricultural productivity through genetic
improvement of plants, delivery of genes and drug molecules to specific sites at cellular
levels, and nano-array based gene-technologies for gene expressions in plants and
animals under stress conditions. The potential is increasing with suitable techniques and
sensors being identified for precision agriculture, natural resource management, early
detection of pathogens and contaminants in food products, smart delivery systems for
agrochemicals like fertilizers and pesticides, smart systems integration for food
processing, packaging and other areas like monitoring agricultural and food system
security. Further developments in nanotechnology in this sector can be expected to
become the main economic driving forces in the long run and benefit consumers,
producers, farmers, ecosystems, and the general society at large.
In India, the importance of research and development in nanotechnology has been
recognized as of paramount importance. If Indian agriculture is to attain its broad national
goal of sustainable agricultural growth of over 4%, it is important that the
nanotechnology research is extended to the agricultural total production-consumption
system, that is, across the entire agricultural value chain.
Nanotechnology will give rise to a host of novel social, ethical, philosophical and
legal issues. It is important to have a regulatory mechanism in place to predict and work
to alleviate anticipated problems.
INTRODUCTION
Imagine a supercomputer a billion times more powerful than today’s and yet so
small it would be barely visible by a light microscope. Fleets of medical robots smaller
than a cell roaming our bodies eliminating bacteria, clearing out clogged arteries,
reversing the ravages of old ages and effectively making us immortal. Clean factories
manufacturing without having to worry about pollution choking up the environment.
Cheap and abundant solar energy replacing conventional fossil fuels like oil, coal and
gas. Building materials that are stronger, lighter and cheaper than the ones used in today’s
2

3. rockets, making lunar vacations no more expansive than says a trip to South Pole. A
world where material abundance for all the people becomes a reality.
Sounds too good to be true? Not for the new breed of scientists who believe that
st
the 21 century could see all these science fiction dreams come true thanks to
nanotechnology, a hybrid of chemistry and engineering that has opened up a whole new
world of possibilities which If taken to their logical conclusion would completely change
us and the world as we know it today. Indeed, so exciting are the prospects of this
revolutionary science that countries all over the world are investing in the research and
development of nanotechnology. Clearly nanotechnology is slowly but surely capturing
the attention of the scientific community, the media and no the public. But just what
exactly is nanotechnology and why everyone talking about it?
WHAT IS NANOTECHNOLOGY?
Nanos: Greek term for dwarf, Technology: visualize, characterize, produce and
manipulate matter of the size of 1 – 100 nm.
Nanotechnology is manufacturing at the molecular level- building things from
Nano-scale components. Nanotechnology proposes the construction of novel Nano-scale
devices possessing extraordinary properties. Through the developments of such
instruments and technique it is becoming possible to study and manipulate individual
atoms.
At present, conventional manufacturing techniques manipulate billions of atoms
at a time using large scale deformation methods like pounding and chipping. In the
future, Molecular nanotechnology” will allow very complete control over the placement
of individual atoms.
Nanotechnology is often referred to as “bottom up” manufacturing because it
aims to start with the smallest possible building materials, atoms using them to create a
desired product. Working with individual atoms allow “atom –by –atom “design of
structures. Nanotechnology can eliminate unwanted byproducts. Nanotechnology would
allow us to get essentially every atom in the right place, make almost any structure
consistent with the most of law of physics and chemistry that we can specify in atomic
detail and have manufacturing costs not greatly exceeding the cost of the required raw
materials and energy.
Related and interwoven fields include, but are not limited to: Nanomaterials,
Nanomedicine, Nanobiotechnology, Nanolithography, Nanoelectronics, Nanomagnetics,
Nanorobots, Biodevices [biomolecular machinery], AI, MEMS [MicroElectroMechanical
Systems], NEMS [Nano Electro Mechanical Systems], Biomimetic Materials, Micro
encapsulation, and many others.
DEFINITION
3

4. • “Nanotechnology is the Design, Fabrication and Utilization Of materials,
Structures, devices and systems through control of matter on the nanometer length
scale and exploitation of novel phenomena and properties (physical, chemical,
biological) at that length scale In At Least One Dimension”.
• “A manufacturing technology able to inexpensively fabricate most structures
consistent with natural laws and to do so with molecular precision”.
• “The precision, placement, measurement, manipulation and modeling of
nanometer scale matter”.
• “The interactions of cellular and molecular components and engineered materials
typically cluster of atoms, molecules and molecular fragments at the most
elemental level of biology”.
• “By taking advantage of quantum-level properties, MNT allows for
unprecedented control of the material world, at the nanoscale, providing the
means by which systems and materials can be built with exact specifications and
characteristics”.
Emergence of Nanotechnology
The first so-called scientific study of nanoparticles took place way back in 1831,
when Michael Faraday investigated the ruby red colloids of gold and made public that the
color was due to the small size of the metal particles. Gold and silver have found their
way into glasses for over 2000 years, usually as nanoparticles. They have most frequently
been employed as colorants, particularly for church windows. Until 1959, nobody had
thought of using atoms and molecules for fabricating devices. It was first envisioned by
Nobel Laureate Physicist Richard Feynman at a lecture entitled “There is plenty of room
at the bottom”. It was much later in 1974 that Norio Taniguchi, a researcher at the
University of Tokyo, Japan used the term “nanotechnology” while engineering the
materials precisely at the nanometer level. The primary driving force for miniaturization
at that time came from the electronics industry, which aimed to develop tools to create
smaller electronic devices on silicon chips of 40–70 nm dimensions. The use of this term,
“nanotechnology” has been growing to mean a whole range of tiny technologies, such as
material sciences, where designing of new materials for wide-ranging applications are
concerned; to electronics, where memories, computers, components and semiconductors
are concerned; to biotechnology, where diagnostics and new drug delivery systems are
concerned.
THE PIONEERS:
4

5. The word “Nanotechnology” coined in 1974 by Norio Taniguchi at the
University of Tokyo. During the 1950s Arthur von Hippel, an electrical engineer from
the Massachussetts Institute of Technology (MIT) coined the term “molecular
engineering” and predicted the feasibility of constructing nanomolecular devices.
However it was in December 29, 1959, the American physicist Richard Feynman gave a
seminal lecture to the American Physical Society entitled “There’s Plenty of Room at
the Bottom”. In this he discussed the benefits to society that would accrue if we were
able to manipulate matter and manufacture artifacts with precision on a scale of a few
atoms across, which corresponds to a dimension of about one nanometer. He correctly
foresaw, for example, the impact that miniaturization would have on the capabilities of
electronic computers; he also predicted the development of the methods that are now
used to make integrated circuits and the emergence of techniques for writing extremely
fine patterns with beams of electrons. He even mooted the possibilities of making
machines at the molecular scale, which would enable us to manipulate chemical and
biological molecules. Forty years on from this lecture, technologists working in the field
of nanotechnology are starting to realize some of the ideas originally propounded by
Feynman, and many others that were not foreseen at that time.
Greg Binnig and Heinrich Rohrer in 1985 invented the scanning tunneling
microscope. Eric Drexler, chairman of the Foresight Institute (1970s) in his book “Engine
5

6. of creation” has been written that future was one where everything would be built from
the bottom up by tiny machines “nanomachines” or “assemblers” that would be able to
build large scale objects that were perfect on the atomic scale.
Consequences of Miniaturization
Every substance regardless of composition exhibits new properties when the size
is reduced to less than 100 nm. The electronic structure of a nanocrystal critically
depends on its size. For small particles, the electronic energy levels are not continuous as
in bulk materials, but discrete. This arises primarily due to confinement of electrons
within particles of dimension smaller than the bulk electron delocalization length; this
process is termed as quantum confinement. Noble metal and semiconductor nanoparticles
are unique examples of this principle. Thus, the properties of traditional materials change
at nano level due to the quantum effect and the behavior of surfaces start to dominate the
behavior of bulk materials. The optical, electrical, mechanical, magnetic, and chemical
properties can be systematically manipulated by adjusting the size, composition, and
shape of the nanoscale materials. Nanomaterials have tremendous potential applications
in catalysis, photocatalysis,optoelectronics, single-electron transistors, light emitters,
nonlinear optical devices, hyperthermia treatment for malignant cells, magnetic memory
storage devices, magnetic resonance imaging enhancement, cell labeling, cell tracking, in
vivo imaging, and DNA detection. The wide range of applications shown by
nanomaterials is mainly due to (i) large surface area and (ii) small size. Electron
transport, manifested in phenomena like Coloumb blockade, as well as the catalytic and
thermodynamic properties of structures can be tailored when one can rationally design
materials on this length scale. Therefore, analytical tools and synthetic methods allow one
to control composition and design on this nanometer range and will undoubtedly yield
important advances in almost all fields of science.
NOBEL PRIZES FOR ELUCIDATING ATOMS AND SUBATOMIC
PARTICLES.
NOBEL
S. No. WINNERS ACHIEVEMENT
PRIZE
1. Gerd Binnig, Scanning Tunneling Microscope. 1986
Heinrich Rohrer.
2. Hans Dehmelt, Traps to isolate atoms and subatomic species. 1989
Wolfgang Paul.
3. George Charpak Subatomic Particle detectors 1992
6

7. 4. Clifford Schull, Neutron Diffraction technique for Structure 1994
Bertram Brockhouse. determination
5. Steven Chu, Claude Methods to cool and trap atoms with Laser light 1997
Cohen -Tannoudji,
William Phillips
HOW BIG IS NANOTECHNOLOGY?
"Nanometer" (abbreviated nm), derived from the Greek word for midget,
"NANO" is a metric prefix and indicates a billionth part (10-9). A micron is a millionth of
a meter, which is the scale that is relevant to building computers, computer memory, and
logic devices. A nanometer is one thousandth of a micron, and a thousandth of a millionth
of a meter (a billionth of a meter). A nanometer is about the width of six bonded carbon
atoms, and approximately 40,000 are needed to equal the width of an average human hair.
Sizes of nanoscale objects –Nature vs. fabrication
Object Diameter
Hydrogen atom 0.1nm
Buckminsterfullerene (C60 ) 1.0 nm
Six carbon atoms aligned 1.0 nm
DNA (width) 2.0 nm
Nanotube 3-30 nm
Proteins 5-50 nm
Quantum Dots (of CdSe) 8.0 nm
Dip pen nanolithography features 10-15 nm
Dendrimers 10 nm
Microtubules 25nm
Ribosome 25 nm
Virus 75-100 nm
Nanoparticles range from 1-100 nm
Semiconductor chip features 90 nm
WHY NANOTECHNOLOGY?
It would enable computer designers to break through the Moore’s law, Intel co-
founder Dr. Gordon Moore predicted that technology that went into integrated circuits
would roughly double in power every 12-18 months. That is why the latest Pentium V
chip clocking 3.2 gigahertz is about 25,000 times faster and packs 25,000 as the first
7

8. ever microchip, the Intel 4004 of 1971. Physicists say it will takes at least 10 years at the
most before we are able to dream up a bigger, better, microchip on that slab of silicon.
And that is where nanotechnology comes in: the ability to fashion electronic circuits–
entire computers –with atom length nanowires or nanotubes, made from carbon rather
than silicon may allow computer hardware to progress beyond physical barriers of
Moore’s law.
• Limitations of resources: Waste problem.
• Necessity: Increasing population, density increases and demand for new
technology.
NANOTECHNOLOGY IS MULTIDISCIPLINARY
WHAT IS UNIQUE ABOUT NANOTECHNOLOGY?
• Small size (High surface to volume ratio), therefore requires self assemblers.
• Significantly higher hardness, breaking strength and toughness at low
temperatures and super plasticity at high temperatures, the emergence of
additional electronic states, high chemical selectivity of surface sites and
significantly increased surface energy.
8

9. • New entry ways (high mobility in human body, plants and environment).
Applications of Nanotechnology in Agriculture
 Crop improvement
 Nanobiotechnology
 Analysis of gene expression and Regulation
 Soil management
 Plant disease diagnostics
 Efficient pesticides and fertilizers
 Water management
 Bioprocessing
 Post Harvest Technology
 Monitoring the identity and quality of agricultural produce
 Precision agriculture
Nanotechnology for Crop Improvement
DNA in Nano World
The DNA molecule has appealing features for use in nanotechnology: its
minuscule size, with a diameter of about 2 nanometers, its short structural repeat (helical
pitch) of about 3.4–3.6 nm, and its ‘stiffness’, with a persistence length (a measure of
stiffness) of round 50 nm. There are two basic types of nanotechnological construction:
‘top-down’ systems are where microscopic manipulations of small numbers of atoms or
molecules fashion elegant patterns, while in ‘bottom-up’ constructions, many molecules
self-assemble in parallel steps, as a function of their molecular recognition properties. As
a chemically based assembly system, DNA will be a key player in bottom-up
nanotechnology. The origins of this approach date to the early 1970s, when in vitro
genetic manipulation was first performed by tacking together molecules with ‘sticky
9

10. ends’. A sticky end is a short single-stranded overhang protruding from the end of a
double-stranded helical DNA molecule. Like flaps of Velcro, two molecules with
complementary sticky ends — that is, their sticky ends have complementary
arrangements of the nucleotide bases adenine, cytosine, guanine and thymine — will
cohere to form a molecular complex. Sticky-ended cohesion is arguably the best example
of programmable molecular recognition: there is significant diversity to possible sticky
ends (4N for N-base sticky ends), and the product formed at the site of this cohesion is the
classic DNA double helix. Likewise, the convenience of solid support-based DNA
synthesis3 makes it is easy to program diverse sequences of sticky ends. Thus, sticky
ends offer both predictable control of intermolecular associations and predictable
geometry at the point of cohesion. Perhaps one could get similar affinity properties from
antibodies and antigens, but, in contrast to DNA sticky ends, the relative three-
dimensional orientation of the antibody and the antigen would need to be determined for
every new pair. The nucleic acids seem to be unique in this regard, providing a tractable,
diverse and programmable system with remarkable control over intermolecular
interactions, coupled with known structures for their complexes.
Nanobiotechnology: Molecular biology complementing Nanotechnology
The credit for the term "nanobiotechnology" goes to Lynn W. Jelinski, a
biophysicist at Cornell University. Nanobiotechnology joins the breakthroughs in
nanotechnology to those in molecular biology. Molecular biologists help
nanotechnologists understand and access the nanostructures and nanomachines designed
by 4 billion years of natural engineering and evolution — cell machinery and biological
molecules. Exploiting the extraordinary properties of biological molecules and cell
processes, nanotechnologists can accomplish many goals that are difficult or impossible
to achieve by other means. For example, rather than build silicon scaffolding for
nanostructures, DNA's ladder structure provides nanotechnologists with a natural
framework for assembling nanostructures; and its highly specific bonding properties
bring atoms together in a predictable pattern to create a nanostructure. Nanotechnologists
also rely on the self-assembling properties of biological molecules to create
nanostructures, such as lipids that spontaneously form liquid crystals.
DNA has been used not only to build nanostructures but also as an essential
component of nanomachines. Most appropriately, DNA, the information storage
molecule, may serve as the basis of the next generation of computers. As microprocessors
and microcircuits shrink to nanoprocessors and nanocircuits, DNA molecules mounted
onto silicon chips may replace microchips with electron flow-channels etched in silicon.
Such biochips are DNA-based processors that use DNA's extraordinary information
10

11. storage capacity. Conceptually, they are very different from the DNA chips discussed
below. Biochips exploit the properties of DNA to solve computational problems; in
essence, they use DNA to do math. Scientists have shown that 1,000 DNA molecules can
solve in four months computational problems that require a century for a computer to
solve. Other biological molecules are assisting in our continual quest to store and transmit
more information in smaller places. For example, some researchers are using light-
absorbing molecules, such as those found in our retinas, to increase the storage capacity
of CDs a thousand-fold.
Nanobiotechnology is an emerging area of opportunity that seeks to fuse
nano/microfabrication and biosystems to the benefit of both. It relates to all applications
of genomics including mammalian, plant and microbial. It provides the basic tools and
subsequently the technology for gathering sequence information and designing
innovative devices to probe questions related to the biological importance of the genomic
information and the application of this knowledge in diverse fields, particularly medicine
and agriculture.
Potential Applications of Nanobiotechnology in Agriculture
• High throughput DNA sequencing and nanofabricated gel-free systems
• Microarrays and expression profiling
• Increasing the speed and power of disease diagnostics
• Creating bio-nanostructures for getting functional molecules into cells
• Miniaturizing biosensors
The impact of nanobiotechnology may be immediately felt in the following areas:
Nanofabricated Gel-free Systems and High Throughput DNA Sequencing
As a central process, DNA sequencing needs to be improved in terms of its
throughput and accuracy. Nanofabrication technology will be critical toward this goal
both in terms of improving existing methods as well as delivering novel approaches for
sequence detection. The scaling down in size of the current sequencing technology allows
the process to be more parallel and multiplex. Research in nanobiotechnology is
advancing toward the ability to sequence DNA in nanofabricated gel-free systems, which
would allow for significantly more rapid DNA sequencing. Coupled with powerful
approaches such as association genetic analysis, DNA sequencing data of the crop
germplasm, including the cultivated crop gene pool and the wild relatives can potentially
provide highly useful information about molecular markers associated with
agronomically and economically important traits. Thus, nanobiotechnology can enhance
the pace of progress in molecular marker-assisted breeding for crop improvement.
11

12. Microarrays and Expression Profiling
Microarray-based hybridization methods allow to simultaneously measure the
expression level for thousands of genes. Such measurements contain information about
many different aspects of gene regulation and function, and indeed this type of
experiments has become a central tool in biological research. The development of novel
formats for sequence determination and patterns of genomic expression which can have
significantly higher throughput than current technologies is vital. Thousands of DNA or
protein molecules are arrayed on glass slides to create DNA chips and protein chips,
respectively. Recent developments in microarray technology use customized beads in
place of glass slides. Overall, nanofabrication techniques can be used, for example, to
pattern surface chemistry for a variety of biosensor and biomedical applications.
Three areas which exemplify this are:
• Determination of new genomic sequences
• Scanning of genes for polymorphism that might have an impact on phenotype
• Comprehensive survey of the pattern of gene(s) expression in organisms when
exposed to biotic/abiotic stress.
The fundamental principle underlying the microarray technology has inspired researchers
to create many types of microarrays to answer scientific questions and discover new
products.
DNA Microarrays: DNA microarrays are being used to:
• detect mutations in disease-related genes
• monitor gene activity
• identify genes important to crop productivity
• improve screening for microbes used in bioremediation
Gene sequence and mapping data mean little until we determine what those genes do—
which is where protein arrays come in.
Protein Microarrays: While going from DNA arrays to protein arrays is a logical step, it
is by no means simple to accomplish. The structures and functions of proteins are much
more complicated than that of DNA, and proteins are less stable than DNA. Each cell
type contains thousands of different proteins, some of which are unique to that cell's job.
In addition, a cell's protein profile varies with its health, age, and current and past
environmental conditions.
12

13. Protein microarrays are being used to:
• discover protein biomarkers that indicate disease stages
• assess potential efficacy and toxicity of pesticides (natural and synthetics)
• measure differential protein production across cell types and developmental stages,
and in both healthy and diseased states
• study the relationship between protein structure and function evaluate binding
interactions between proteins and other molecules
Atomically Modified Seeds:
In March 2004, ETC Group reported on a nanotech research initiative in Thailand
that aims to atomically modify the characteristics of local rice varieties. In a three-year
project at Chiang Mai University’s nuclear physics laboratory, researchers “drilled” a
hole through the membrane of a rice cell in order to insert a nitrogen atom that would
stimulate the rearrangement of the rice’s DNA. So far, researchers have been able to alter
the colour of a local rice variety from purple to green. In a telephone interview, Dr.
Thirapat Vilaithong, director of Chiang Mai’s Fast Neutron Research Facility, told
Biodiversity Action Thailand (BIOTHAI) that their next target is Thailand’s famous
Jasmine rice. The goal of their research is to develop Jasmine varieties that can be grown
all year long, with shorter stems and improved grain colour. One of the attractions of this
nano-scale technique, according to Dr. Vilaithong, is that, it does not require the
controversial technique of genetic modification. “At least we can avoid it.”
Low-energy ion beam bombardment at energy levels in the range of 60–125 keV
and ion fluences (dose) of 1×1016–5×1017 ions/cm2 was chosen for mutation induction
in Thai jasmine rice (Oryza sativa L. cv. KDML 105) at Chiang Mai University. One of
the rice mutants designated BKOS6 was characterized. The rice mutant was obtained
from KDML 105 rice embryos bombarded with N++N2+ ions at an energy level of 60 keV
and ion fluence of 2×1016 ions/cm2. Phenotypic variations of BKOS6 were short in
stature, red/purple color in leaf sheath, collar, auricles, ligule, and dark brown stripes on
leaf blade, dark brown seed coat and pericarp. The mutant's reproductive stage was found
in off-season cultivation (March–July). HAT-RAPD (High Annealing Temperature-
Random Amplified Polymorphic DNA) was applied for analysis of genomic variation in
the mutant. Of 10 primers, two primers detected two additional DNA bands at 450 bp and
400 bp. DNA sequencing revealed that the 450 bp and the 400 bp fragments were 60%
and 61% identity to amino acid sequence of flavanoid 3′hydroxylase and cytochrome
P450 of O. sativa japonica, respectively.
13

14. Figure: The rice mutants designated BKOS6 was derived by bombardment
with N++N2+ ions from KDML 105 rice embryos.
Synthetic Tree
In trees, evaporation of water from leaf cells called spongy mesophyll pulls water
up through hollow cells in the trunk
14

15. (spongy mesophyll is the tissue in the lower half of this picture, a cross-section through a
leaf). The strong, cohesive properties of water, responsible for its powerful surface
tension, allow the water to exist at large negative pressures. But even the smallest bubble
would explosively expand into the water, disrupting its flow in a process known as
cavitation. The interface between the plant’s water system and the air, formed by the
spongy mesophyll, must allow water to pass, but not the gas molecules that would cause
cavitation.
Figure: The synthetic hydrogel mimics the trnaspiartion pattern of a typical plant
system.
Trees grow many times taller - more than 100 metres in the case of the tallest
redwoods. Yet they supply their leaves with a constant flow of water. They achieve this
feat by keeping the water high up in their trunks under pressures many atmospheres
below that of a vacuum.
Wheeler and Stroock report a duplication of this trick: they have created a tiny
‘synthetic tree’ through whose trunk water flows at pressures of around -10 atmospheres.
To create their tree, Wheeler and Stroock use a hydrogel, which mimics the mesophyll by
holding water in molecular-scale pores, smaller than those of other porous solids. As their
respective ‘root’ and ‘leaf’, the authors formed two networks of channels, 10 micrometres
in diameter, in a sheet of poly(hydroxyethyl methacrylate), and connected them by a
single channel, the ‘trunk’. With the ‘root’ exposed to a source of water and the ‘leaf’ to a
stream of damp air, water flows through the system powered solely by ‘leaf’ evaporation.
The pressures developed in the trunk are some 15 times more negative than in any
previously reported pumping system.
The device is shown in Figure of the paper. It is just 5 cm long, and the flow is a
little over 2 micrograms of water per second — but from such small acorns do mighty
oaks grow. The synthetic tree can provide a test device for theories of tree physiology
and, scaled-up, the technology could find uses in passive pumps or cooling devices —
evaporation makes the ‘leaf’ a heat sink. Also, the large negative pressures developed
might be used to drag water out of even quite dry soils, simultaneously filtering out
impurities by passage through the ‘root’ hydrogel. This process, which the authors dub
“reverse reverse osmosis”, could form the basis of solar-powered mining of pure water in
arid or contaminated environments.
Silica beaks Plant Cell
Imagine a tiny bundle of parallel tubes with each tube containing liquid and
having a cap that is removable at will. How useful might these objects be in
15

16. biotechnology? François Torney, Brian Trewyn and colleagues1 at Iowa State University
describe the use of mesoporous silica nanoparticles (MSNs) to deliver foreign genetic
material into plant cells in a process known as transformation. They further show that the
nanoparticles can carry and release effectors - small molecules that induce the expression
of genes - within the plant cells in a controlled fashion.
Figure. Delivering DNA and their
effector molecules into intact plant cells using mesoporous silica nanoparticles. a) A
typical plant cell, illustrating the thick cell wall (cw). b) After action of the gene gun,
MSNs (small circles), carrying the small effector molecule (β-estradiol) within the gold-
capped structure and externally coated with plasmid DNA, penetrate the cell wall and, in
some cases, enter the cytoplasm.
Torney and co-workers explored both the surface attachment and encapsulation
properties of MSNs, using plant cells as the test-bed. Plants have a thick cell wall that
impedes delivery of materials from the exterior (Fig. a). In preliminary experiments,
Torney and colleagues incubated protoplasts — plant cells whose cell walls are removed
-with fluorescently labelled MSNs. It was found that modifying the MSN surface with
triethylene glycol was necessary for MSNs to penetrate the cells. This surface
16

17. modification also allowed DNA plasmids (cloned DNA segments) to adsorb onto the
MSN surface.
Figure. Designer nanotubes based on mesoporous silica can now penetrate the
thick cell walls of plants and deliver DNA and their activators. This opens the way to
precisely manipulate gene expression in plants at the single-cell level.
After entering the protoplasts, the plasmid DNA was released from the MSNs and
the green fluorescent protein (GFP) marker encoded in the DNA was expressed in the
cells and detected by microscopy. Delivery is efficient because the minimum amount of
DNA required to detect marker expression was 1,000-fold lower than that required when
using conventional methods to deliver DNA into protoplasts. It seems that using MSNs as
a means to deliver DNA in this way should gain popularity for protoplast-based gene
expression studies.
Although delivering material into protoplasts is important, it is not a particularly
common approach in plant biotechnology because the cell walls must first be removed. A
popular tool used to deliver materials into plants with intact cell walls is the ‘gene gun’.
The carrier particles, usually coated with DNA, enter the cells through the walls by
bombardment using high-pressure gases or, less commonly, explosive rounds.
Despite the destructive nature of this method, recovery is efficient enough to
allow the DNA to be expressed in the plants. The advantage of using MSNs with the gene
gun is that both the DNA and small effector molecules can be delivered at the same time.
This work stimulates a number of questions. What might be the effect of including
combinations of effector molecules within the MSNs, and/or combinations of plasmid
DNA on their surfaces? Can MSNs be designed to uncap under more selective conditions
(for example, using laser light or in response to chemical changes in the plant cells)? Can
MSNs be designed so they can be recapped? Answering these questions is by no means
17

18. easy, but the promise shown by MSNs in general, and this work in particular, suggests
many more breakthroughs will emerge in this area.
Hormone and Antibiotics Delivery in plants
Protein and nucleic acid drugs usually have poor stability in physiological
conditions. It is therefore essential for these drugs to be protected en route to their target
disease sites in the body.
Controlled release involves the
combination of a biocompatible material or
device with a drug to be delivered in a way that
it can be delivered to and released at diseased
sites in a designed manner. Drug-delivery
systems may rescue potential drug candidates
by increasing solubility and stability by the
application of coating of polymerdrug
conjugates, polymeric micelles, polymeric
nanospheres and nanocapsules, and polyplexes.
Polymer-drug conjugates (520nm) represent the smallest nanoparticulate delivery
vehicles. The polymers used for such purposes are usually highly water-soluble and include
synthetic polymers (for example, poly(ethylene glycol) (PEG)) and natural polymers (such as
dextran).
E.g. a cyclodextrin-based polymer developed at Insert Therapeutics increases the slow
and sustained release of streptomycin, in plants against viruses.
Nanofuels
Levesque’s lab (University of Otawwa) is working on nanoconversion of
agricultural materials into valuable products. The design and development of new
nanocatalysts for the conversion of vegetable oils into biobased fuels and biodegradable
solvents is already under scientific examination, and could be greatly enhanced with the
help of nanotechnological abilities. This is based on the concept that the organic fuels at
nano scale would be able to give greater energy with lesser energy loss during
conversion.
Particle Farming
Nanoparticles may not be produced in a laboratory, but grown in fields of
genetically engineered crops – what might be called “particle farming.”
18

19. Research from the University of Texas-El Paso confirms that plants can also soak
up nanoparticles that could be industrially harvested. In one particle farming experiment,
alfalfa plants were grown on an artificially gold-rich soil; gold nanoparticles in the roots
and along the entire shoot of the plants that had physical properties like those produced
using conventional chemistry techniques, which are expensive and harmful to the
environment.
The metals are extracted simply by dissolving the organic material.
National Chemistry Laboratory in Pune, India have been carrying out similar
work with geranium leaves immersed in a gold-rich solution.
Seeding Iron
Russian Academy of Sciences reports that they have been able to improve the
germination of tomato seeds by spraying a solution of iron nanoparticles on to fields.
They report that application of nano-disperse iron at the rate of 10-30 µg/ml on Tomato
seeds var. Gribovskii leads to stimulator of growth and hastens the process of germination
of seeds simultaneously stimulating the development of the root system. This was
presented by A.M. Prochorov et al., “The influence of very minute doses of nano-
disperse iron on seed germination,” presentation given at the Ninth Foresight Conference
on Molecular Nanotechnology, 2001.
Using Nanosensors on Crops and Nanoparticles in Fertilisers
Tiny sensors offer the possibility of monitoring pathogens on crops and livestock
as well as measuring crop productivity. In addition, nanoparticles could increase the
efficiency of fertilisers. However, the Swiss insurance company SwissRe warned in a
report in 2004 that they could also increase the ability of potentially toxic substances,
such as fertilisers, to penetrate deep layers of the soil and travel over greater distances.
A nanotech research initiative in Thailand aims to atomically modify the
characteristics of local rice varieties - including the country's famous jasmine rice- and to
circumvent the controversy over Genetically Modified Organisms (GMOs). Nanobiotech
takes agriculture from the battleground of GMOs to the brave new world of Atomically
Modified Organisms (AMOs).
Nanocides: Pesticides via Encapsulation
Pesticides containing nano-scale active ingredients are already on the market, and
many of the world’s leading agrochemical firms are conducting R&D on the development
of new nano-scale formulations of pesticides (see below, Gene Giants: Encapsulation
R&D). For example: BASF of Germany, the world’s fourth ranking agrochemical
19

20. corporation (and the world’s largest chemical company), recognizes nanotech’s potential
usefulness in the formulation of pesticides. BASF is conducting basic research and has
applied for a patent on a pesticide formulation, “Nanoparticles Comprising a Crop
Protection Agent,” that involves an active ingredient whose ideal particle size is between
10 and 150 nm. The advantage of the nano-formulation is that the pesticide dissolves
more easily in water (to simplify application to crops); it is more stable and the killing-
capacity of the chemical (herbicide, insecticide or fungicide) is optimized. Bayer Crop
Science of Germany, the world’s second largest pesticide firm, has applied for a patent on
agrochemicals in the form of an emulsion in which the active ingredient is made up of
nanoscale droplets in the range of 10-400 nm. (An emulsion is a material in which one
liquid is dispersed in another liquid – both mayonnaise and milk are emulsions.)
The company refers to the invention as a “microemulsion concentrate” with
advantages such as reduced application rate, “a more rapid and reliable activity” and
“extended long-term activity.” Syngenta, headquartered in Switzerland, is the world’s
largest agrochemical corporation and third largest seed company. Syngenta already sells
pesticide products formulated as emulsions containing nano-scale droplets.
Like Bayer Crop Science, Syngenta refers to these products as microemulsion
concentrates. For example, Syngenta’s Primo MAXX Plant Growth Regulator (designed
to keep golf course turf grass from growing too fast) and its Banner MAXX fungicide
(for treating golf course turf grass) are oil-based pesticides mixed with water and then
heated to create an emulsion. Syngenta claims that both products’ extremely small
particle size of about 100 nm (or 0.1 micron) prevents spray tank filters from clogging,
and the chemicals mix so completely in water that they won’t settle out in the spray tank.
Banner MAXX fungicide will not separate from water for up to one year, whereas
fungicides that contain larger particle size ingredients typically require agitation every
two hours to prevent misapplications and clogging in the tank. Syngenta claims that the
particle size of this formulation is about 250 times smaller than typical pesticide particles.
According to Syngenta, it is absorbed into the plant’s system and cannot be washed off by
rain or irrigation
Soil Binder - Using Chemical Reactions at the Nanoscale to Bind Soil Together
In 2003, ETC Group reported on a nanotech-based soil binder called SoilSet
developed by Sequoia Pacific Research of Utah (USA). SoilSet is a quick-setting mulch
which relies on chemical reactions on the nanoscale to bind the soil together. It was
sprayed over 1,400 acres of Encebado mountain in New Mexico to prevent erosion
following forest fires, as well as on smaller areas of forest burns in Mendecino County,
California.
20

21. Soil Clean-Up Using Iron Nanoparticles
A number of approaches are being developed to apply nanotechnology and
particularly nanoparticles to cleaning up soils contaminated with heavy metals and PCBs.
Dr. Wei-Xang Zhang has pioneered a nano clean-up method of injecting nano-scale iron
into a contaminated site. The particles flow along with the groundwater and
decontaminate en route, which is much less expensive than digging out the soil to treat it.
Dr. Zhang’s tests with nano-scale iron show significantly lower contaminant levels within
a day or two. The tests also show that the nano-scale iron will remain active in the soil for
six to eight weeks, after which time it dissolves in the groundwater and becomes
indistinguishable from naturally occurring iron.
Consumer products:
• Nanoscale powders, in their free form, without consolidation or blending, used by
cosmetics manufacturers:
– Titanium Dioxide and Zinc Oxide powders for facial base creams and
sunscreen lotions.
– Iron Oxide powders as base material for rouge and lipstick.
• Improved wear and corrosion resistance. Nanocomposite materials, with increased
impact strength, for automobiles.
Disease diagnosis:
• Sample Retrieval: Develop retrieval nanosystems for sampling specific
components (from air, plant and animal organisms, water, and soil).
• Pathogen Detection: Develop methods of near real time pathogen detection and
location reporting using a systems approach, integrating nanotechnology micro-
electromechanical systems (MEMS), wireless communication, chip design, and
molecular biology for applications in agricultural security (economic,
agricultural terrorism, agricultural forensics) and food safety
Quality maintain
Identity Preservation (IP) is a system that creates increased value by providing
customers with information about the practices and activities used to produce a particular
crop or other agricultural product. Certifying inspectors can take advantage of IP as a
21

22. more efficient way of recording, verifying, and certifying agricultural practices. Today,
through IP it is possible to provide stakeholders and consumers with access to
information, records and supplier protocols regarding such information as farm of origin,
environmental practices used in production, food safety and quality and information
regarding animal welfare issues. Some food or processed agricultural products may be
stored for years, with intermittent samplings for storage pathogens or environmental
storage problems. Each day shipments of food and other agricultural products are moved
all over the world. Currently, there are financial limitations in the numbers of inspectors
that can be employed at critical control points for the safe production, shipment and
storage of food and other agricultural products. Quality assurance of agricultural
products’ safety and security could be significantly improved through IP at the nanoscale.
Nanoscale IP holds the possibility of the continuous tracking and recording of the history
which a particular agricultural product experiences. We envision nanoscale monitors
linked to recording and tracking devices to improve identity preservation of food and
agricultural products.
Smart Treatment Delivery Systems
Today, application of agricultural fertilizers, pesticides, antibiotics, probiotics and
nutrients is typically by spray or drench application to soil or plants, or through feed or
injection systems to animals. Delivery of pesticides or medicines is either provided as
“preventative” treatment, or is provided once the disease organism has multiplied and
symptoms are evident in the plant or animal. Nanoscale devices are envisioned that
would have the capability to detect and treat an infection, nutrient deficiency, or other
health problem, long before symptoms were evident at the macro-scale. This type of
treatment could be targeted to the area affected.
“Smart Delivery Systems” for agriculture can possess any combination of the
following characteristics: time-controlled, spatially targeted, self regulated, remotely
regulated, preprogrammed, or multifunctional characteristics to avoid biological barriers
to successful targeting. Smart delivery systems also can have the capacity to monitor the
effects of the delivery of pharmaceuticals, nutraceuticals, nutrients, food supplements,
bioactive compounds, probiotics, chemicals, insecticides, fungicides, vaccinations, or
water to people, animals, plants, insects, soils and the environment.
Nanotechnology and Indian Initiatives
22

23. At present, USA leads with a 4 year, 3.7 billion USD investment through its
Nanotechnology Development Programme (NDP).
The market for the nanotechnology was 7.6 billion USD in 2003 and is expected
to be 1 trillion USD in 2011
However, the full potential of nanotechnology in the agricultural and food
industry has still not been realised.
23

24. 24

25. Present area of activities in the field of Nanotechnology in India
The priority areas identified in Agriculture are:
• Detecting contamination in raw agriculture products
• Development of nano tubes devices to diagnoses diseases in agriculture crops.
• To detect carcinogenic pathogens and bio sensors for improved and contamination
free agriculture products.
• Use of nano particles with bio compatible Chitosan
National Challenge Program on Nanobiotechnology and Food and
Health Security
National Physical Laboratory, New Delhi has been entrusted as the nodal organization
• To meet the Millennium Development Goal of UN
25

26. • To prioritize the area of research and to measure the research outlay and scientific
and social outcome
• To coordinate the research between ICAR, CSIR, ICMR, DST and DBT
organizations.
DST has invested approx. $20million for the period 2004-2009.
OBSTACLES:
Unlike building with traditional materials that stay where you put them, atoms
and molecules are volatile and will rearrange themselves constantly to maintain stability.
So positional Control: must be achieved, and self-replication is necessary to reduce costs.
It will also allow atoms to be placed precisely without parts bumping into each other in
the wrong way. Eric Drexler has proposed a robotic arm to control the placement of
atoms. The Stewart platform, which is stiffer and simpler than Drexler’s robotic arm, has
also been proposed.
Nanotechnology : A Friend or Monster in The Making ?
Current status
Nanobiotechnology is still at its early stages of development the development is
multi-directional and fast-paced. Universities are forming nanotechnology centers and the
number of papers and patent applications in the area is rising quickly.
Realistically, some of these newly developed tools might not have viable
applications and could end-up on the ‘technology shelf’ in the future but offcorse there
are definite benefits.
Nanobiotechnology is interdisciplinary and brings together life scientists and
engineers. This, in turn, fuels further growth of ideas, which would not occur without
these interdisciplinary interactions.
Future trends
Developments will gradually become more ordered and develop sharp focus as
applications mature to produce useful and validated technologies.
The question that whether the coming age of Nanotechnology is the Next technological
revolution everyone talking about is still to be answered?
There is great optimism among scientists, politicians and policy makers who anticipate
significant job creation.
26

27. Opportunities for developing new materials and methods that will enhance our ability to
develop faster, more reliable and more sensitive analytical systems.
Overall the scenario presents us with the view that nanotechnology is here to stay!
Political, social or ethical concerns related to nanotechnology
development
• Is Nanotechnology more acceptable compared to genetically modified products?
• The potential risks in using nanoparticles in agriculture are no different than those
in any other industry.
• Proprietary issues associated with the nano-products.
• Since there is no standardization for the use and testing of nanotechnology,
products incorporating the nanomaterials are being produced without check.
Conclusions
Some of the important conclusions that can be drawn are
• Nanotechnology is the engineering of tiny machines i.e. the ability to build things
from the “bottom up”, manufacturing because it aims to start with the smallest
possible building materials, ATOMS using them to create a desired product.
• By taking advantage of quantum-level properties, MNT allows for unprecedented
control of the material world, at the nanoscale, providing the means by which
systems and materials can be built with exact specifications and characteristics.
• Nanotechnology has wider uses in biotechnology, genetics, plant breeding,
disease control, fertilizer technology, precision agriculture, and allied fields, etc.
SUMMARY:
NANOTECHNOLOGY IN A NUTSHELL
NEW TECHNOLOGY : ATOMIC ENGINEERING
: NEW MATERIALS
: NEW PROPERTIES
SIGNIFICANTS BENEFITS : CLEAN ENERGY
: IMPROVED EFFICIENCY
: BETTER WASTE TTREATMENT
POTENTIAL RISKS : HIGH MOBILITY ?
: NOVEL TOXICITY ?
: CORPORATE LIABILITY ?
27

28. So careful developments to achieve benefits and manage risks requires:
• CLEAR REGULATIONS
• RISK IDENTIFICATION RESEARCH
• RISK MANAGEMENT STANDARDS
• "Nanotechnology will give rise to a host of novel social, ethical, philosophical
and legal issues. It will be important to have a group in place to predict and work
to alleviate anticipated problems”.
• Both the government and the private sector have to join hands and form a “Nano
tech Enterprise". If we take up a mission mode with a clear cut vision, the country
will reap the benefits of Nanoscience and technology.
“Our future lies in Nanotechnology”
We believe that nanotechnology would give us an opportunity, if we take
appropriate and timely action to become one of the important technological nations in the
world. The world market in 2005 is for nano materials, nano tools, nano devices and nano
biotechnology, which put together, is expected to be over hundred billion dollars.
Nanotechnology is a new technology that is knocking at doors. (Source: president
address to scientist and technologists in April 2005 in Delhi.)
28

29. Reference:-
A. Malato, J. Blanco, A. Vidal and C. Richter, “Photocatalysis with
solar energy at a pilot-plant scale: an overview”, (2002),
Applied Catalysis B: Environmental, Vol. 37, 1–15.
A. Mills, L. Punte, and M. Stephan, “An overview of semiconductor
photocatalysis”, (1997), J. Photochem. Photobiol. A., Vol. 108,
1-35.
A. Sugunan, H. C. Warad, C. Thanachayanont, J. Dutta And H.
Hofmann, “Zinc oxide nanowires on non-epitaxial substrates
from colloidal processing for gas sensing applications”,
Nanostructured and Advanced Materials for Applications in
Sensor, Optoelectronic and Photovoltaic Technology, NATO-
Advance Study Institute, Sozopol, Bulgaria, 6-17th September
2004
A.M. Prochorov et al., “The influence of very minute doses of nano-disperse iron on seed
germination,” presentation given at the Ninth Foresight Conference on
Molecular Nanotechnology, 2001.
Annonymous, 2004. Down on the farm: The impact of nano-scale
technologies on food and agriculture. Action Group on Erosion
Technology Concentration, Ottawa, Canada. www.etcgroup.org
B. Phanchaisri, R. Chandet, L.D. Yu, T. Vilaithong, S. Jamjod, S.
Anuntalabhochai. Low-energy ion beam-induced mutation in Thai
jasmine rice (Oryza sativa L. cv. KDML 105) Surface & Coatings
Technology 201 (2007) 8024–8028.
C.F., Chau, Wu, Shiauan-Huei and Gow-Chin Yen. 2007. The
development of regulations for food nanotechnology. Trends in
Food Science and Technology. 18:269-280.
C.I. Moraru, 2003. Nanotechnology: A new frontier in food science.
Food Technology 57(12):24-29.
D. Li, H. Haneda, “Morphologies of zinc oxide particles and their
effects on photocatalysis’, (2003), Chemosphere, Vol. 51(2),
129-37
29

30. D. Maysinger, 2007. Nanoparticles and cells: Good companions and
doomed partnerships. Org. Biomol. Chem. 5:2335-2342.
D. S. Bhatkhande, V. G. Pangarkar and A. A. C. M. Beenackers,
“Photocatalytic degradation for environmental applications – A
Review”, (2001), J. Chem. Technol. Biotechnol, Vol. 77, 102-
116
E. C. Alocilja and S. M. Radke, ‘Market analysis of biosensors for
food safety’, Biosensors and bielectronics, (2003), Vol. 18,
841-846.
ETC Group News Release, “Atomically Modified Rice in Asia?” 25 March
2004. Available on the Internet:
www.etcgroup.org/article.asp?newsid=444
F. Kulzer and M. Orrit, “Single-Molecule Optics”, (2004), Annual
Review of Physical Chemistry, Vol. 55, 585-611
F.R.R. Teles, L.P. Fonseca, Talanta (2008) Trends in DNA biosensors,
Article in press doi:10.1016/j. Talanta.2008.07.024
F.X., Redl, Cho, K.S., Murray, C. B. and O’Brien, S. (2003). Three
dimensional binary super lattices of magnetic nanocrystal
&semiconductor quantum dots. Nature 424(6943), 968-971.
H. C. Warad, S. C. Ghosh, C. Thanachayanont and J. Dutta, ‘Highly
Luminescent Manganese Doped ZnS Quantum Dots for
Biological Labeling’, conference proceedings
‘Smart/Intelligent Materials and Nanotechnology’, Chiang Mai,
Thailand, 1-3 December 2004.
http://www.nano.gov/
J. Dutta and H. Hofmann, “Self-Organization of Colloidal
Nanoparticles”, (2004) Encyclopedia of Nanoscience and
Nanotechnology, Vol. 9, 6 17-640.
J. M. Herrmann, “Heterogeneous photocatalysis: fundamentals
and applications to the removal of various types of aqueous
pollutants, (1999), Catalysis Today Vol. 53, 115–129.
30

31. J. Peral, X. Domenech and D. F. Ollis, “Heterogeneous photocatalysis
for purification, decontamination and deodorization of air”,
(1997), J. Chem. Technol. Biotechnol, Vol. 70, 117-140.
K. Yuen, U. Muller, and J. Lahiri, "Rare earth-doped glass
microbarcodes",(2003), PNAS, Vol. 100, 389-393
Kroto, H. W., Heath, J. R., O’Brian, S. C., Curl, R. F. and Smalley, R. E.,
Nature, 1985, 318, 162–163.
L. C. Torres-Martínez, L. Nguyen, R. Kho, W. Bae, K. Bozhilov, V. Klimov
and R. K Mehra, “Biomolecularly capped uniformly sized
nanocrystalline materials: glutathione-capped ZnS
nanocrystals”, (1999), Nanotechnology Vol. 10, 340-354
L. Vayssieres, K. Keis, S. E. Lindquist and A. Hagfeldt, “Purpose-Built
Anisotropic Metal Oxide material: 3D Highly Oriented Microrod
Array of ZnO” (2001), J Phys. chem. 105, 3350-3352
M. A., Poggi, Bottomley, L. A. and Lillehi, P.T. (2002). Scanning probe
microscopy. Anal. chem. 74, 2851-2862.
M. Blake, “Bibliography of Work on Photocatalytic Removal of
Hazardous Compounds from Water and Air”, (1997), NREL/TP-
430-22197, National Renewable Energy Laboratory, Golden.
M. C., Roco, Williams, R. S., Alivasatos, P., Eds. Nanotechnology
Research Directions: IWGN Workshop Report, Kluwer
Academic Publishers: Norwell, MA, 1999.
M. H. Huang, Y Wu, H. Feick, N. Tran, E. Weber and P. Yang, "Catalytic
.
Growth of Zinc Oxide Nanowires by Vapor Transport" (2001),
Adv. Mater., Vol. 13, 113-1 16.
M. J. Dejneka, A. Streltsov, S. Pal, A. G. Frutos, C. L. Powell, K. Yost,
P. Nanomaterials by J. Dutta and H. Hofmann, Text book in
preparation.
M. K. Hossain, S. C. Ghosh, Y Boontongkong C. Thanachayanont and
.
J. Dutta, “Growth of zinc oxide nanowires and nanobelts for
gas sensing applications”, (2005), Journal of Metastable and
Nanocrystalline Materials, Vol. 23, 27-30
31

32. M. Reches, and E. Gazit. (2003). Casting metal nano-wires within
discrete self-assembled peptide noontides. Science. 300, 625-
627.
P. D. Patel, “(Bio) sensors for measurement of analytes implicated in
food safety: a review” (2002) Trends in analytical chemistry,
Vol. 21, 96-115
P. Liu, Y.W. Zhang and C. Lu, “Finite element simulations of the self-
organized growth of quantum dot superlattices”, (2003), Phys.
Rev. 68, 195314.
P.A. Troshin, R.N. Lyubovskaya, I.N. Ioffe, N.B. Shustova, E. Kemnitz, S.I.
Troyanov, Angew. Chem. Int. Ed. Engl. 44, 234 (2005).
P.M. Ajayan, Nanotechnology how does a nanofibre grow? (2004).
Nature. 427, 402-403.
R. F., Curl, Angew. Chem., Int. Ed. Engl., 1997, 36, 1566– 1576;
Kroto, R., Angew. Chem., Int. Ed. Engl., 1997, 36, 1578–1593;
R. Vacassy, S. M. Scholz, , J. Dutta, C. J. G. Plummer, R. Houriet and H.
Hofmann , “Synthesis of controlled spherical Zinc Sulfide
Particles by Precipitation from Homogeneous Solutions”, (1998),
Journal of American Ceramic Society Vol. 81, 2699-2705
S. R. Nicewarner-Pena, R. G. Freeman, B. D. Reiss, L. He, D. J. Pena, I.
D. Walton, R. Cromer, C. D. Keating and M. J. Natan,
“Submicrometer metallic barcodes” (2001), Science, Vol. 294
(5540), 137-41
T.D. Wheeler, & Stroock, A.D. 2008. The transpiration of water at
negative pressures in a synthetic tree. Nature. 455:208-212.
W., Ranjana. “Thailand embarks on the nano path to better rice and
silk,” Bangkok Post, Jan. 21, 2004. Available on the Internet:
http://www.smalltimes.com/document_display.cfm?document_id=
7266
X. L. Su, Y Li, “Quantum dot biolabeling coupled with
.
immunomagnetic separation for detection of Escherichia coli
O157:H7” (2004), Anal Chem. Vol. 76 (16), 4806-10.
32

33. Y A. Cao, X. T. Zhang, W. S. Yang, H. Du, Y B. Bai, T. J. Li, J. N. Yao,
. .
“Bicomponent TiO2/SnO2 particulate film for photocatalysis”,
(2002), Chem. Mater., Vol. 12, 3445.
Y Xia, Yang, P., Sun, Y Wu, Y Mayers, B., Gates, B., Yin, Y Kim, F., and
., ., ., .,
Yan, H. (2003).One dimensional nanostructures: synthesis,
characterization and application. Adv. Mater.15 (5), 353-389.
33