Download Nanomaterials

Done by : Lee Jin Loong 3P3 09
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a field that takes a materials science-based
approach to nanotechnology
material having at least one dimension 100 nanometres or
less, up to10,000 could fit across a human hair.
Nanomaterials can be nanoscale in one dimension (eg.
surface films),two dimensions (eg. strands or fibres), or three
dimensions (eg. particles). They can exist in single, fused,
aggregated or agglomerated forms with spherical, tubular,
and irregular shapes
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Engineered nanomaterials are materials designed at the
molecular (nanometre) level to take advantage of their small
size and novel properties which are generally not seen in their
conventional, bulk counterparts
Two main reasons why materials at the nano scale can have
different properties are increased relative surface area and
new quantum effects
Nanomaterials have a much greater surface area to volume
ratio than their conventional forms, which can lead to greater
chemical reactivity and affect their strength
At the nano scale, quantum effects can become much more
important in determining the materials properties and
characteristics, leading to novel optical, electrical and
magnetic behaviours.
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Nanomaterials (nanocrystalline materials) are materials
possessing grain sizes on the order of a billionth of a meter
manifest extremely fascinating and useful properties and
exploited for a variety of structural and non-structural
applications
Since nanomaterials possess unique, beneficial chemical,
physical, and mechanical properties, they can be used for a
wide variety of applications. These applications include, but
are not limited to, the following:
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Next-Generation Computer Chips
Kinetic Energy (KE) Penetrators with Enhanced Lethality
Better Insulation Materials
Phosphors for High-Definition TV
Tougher and Harder Cutting Tools
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Suspension (or colloid) of sub-micrometre-sized
particles of gold in a fluid — usually water
Usually either an intense red colour (for particles less
than 100 nm), or a dirty yellowish colour (for larger
particles)
Properties and applications of colloidal gold
nanoparticles depends upon shape. For example, rodlike
particles have both transverse and longitudinal
absorption peak, and anisotropy of the shape affects
their self-assembly.
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Electron Microscopy
◦ Colloidal gold and various derivatives have long been
among the most widely-used contrast agents for
biological electron microscopy
◦ Colloidal gold particles can be attached to many traditional
biological probes such as antibodies, lectins,
superantigens, glycans, nucleic acids and receptors
◦ Particles of different sizes are easily distinguishable in
electron micrographs, allowing simultaneous multiplelabelling experiments
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Health and medical applications
◦ successfully used as a therapy for rheumatoid arthritis in
rats
◦ In a related study, the implantation of gold beads near
arthritic hip joints in dogs has been found to relieve pain.
◦ An in vitro experiment has shown that the combination of
microwave radiation and colloidal gold can destroy the
beta-amyloid fibrils and plaque which are associated
with Alzheimer's disease
◦ The possibilities for numerous similar radiative applications
are also currently under exploration
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In cancer research, colloidal gold can be used to target
tumors and provide detection using SERS (Surface Enhanced
Raman Spectroscopy) in vivo
aman reporters were stabilized when the nanoparticles were
encapsulated with a thiol-modified polyethylene glycol coat.
This allows for compatibility and circulation in vivo
To specifically target tumor cells, the pegylated gold particles
are conjugated with an antibody (or an antibody fragment
such as scFv), against e.g. Epidermal growth factor receptor,
which is sometimes overexpressed in cells of certain cancer
types. Using SERS, these pegylated gold nanoparticles can
then detect the location of the tumor
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nanoparticles of silver
silver particles of between 1 nm and 100 nm in size
While frequently described as being 'silver' some are
composed of a large percentage of silver oxide due to their
large ratio of surface to bulk silver atoms
Many different synthetic routes to silver nanoparticles. They
can be divided into three broad categories: physical vapor
deposition, ion implantation, or wet chemistry
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Over the last decades silver nanoparticles have found
applications in catalysis, optics, electronics and other areas
due to their unique size-dependent optical, electrical and
magnetic properties
Currently most of the applications of silver nanoparticles are
in antibacterial/antifungal agents in biotechnology and
bioengineering, textile engineering, water treatment, and
silver-based consumer products
There is also an effort to incorporate silver nanoparticles into
a wide range of medical devices, including but not limited to
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bone cement
surgical instruments
surgical masks
wound dressings
treatment of HIV-1
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Samsung has created and marketed a
material called Silver Nano, that includes
silver nanoparticles on the surfaces of
household appliances
Silver nanoparticles have been used as the
cathode in a silver-oxide battery
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Fullerenes are a class of allotropes of carbon which
conceptually are graphene sheets rolled into tubes or
spheres. These include the carbon nanotubes (or silicon
nanotubes) which are of interest both because of their
mechanical strength and electrical properties
Fullerenes were under study for potential medicinal use:
binding specific antibiotics to the structure of
resistant bacteria and even target certain types of cancer cells
such as melanoma
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Carbon nanotubes are molecular-scale tubes of graphitic
carbon with outstanding properties. They are among the
stiffest and strongest fibres known, and have remarkable
electronic properties and many other unique
characteristics. Commercial applications have been rather
slow to develop, however, primarily because of the high
production costs of the best quality nanotubes.
These cylindrical carbon molecules have
novel properties that make them potentially useful in many
applications in nanotechnology, electronics, optics and
other fields of materials science, as well as potential uses
in architectural fields.
exhibit extraordinary strength and
unique electrical properties, and are efficient thermal
conductors.
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Nanotoxicology is the study of
the toxicity of nanomaterials. Because of quantum size
effects and large surface area, nanomaterials have unique
properties compared with their larger counterparts
Nanotoxicology is a branch of bionanoscience which deals
with the study and application of toxicity of nanomaterials
Nanotoxicological studies are intended to determine
whether and to what extent these properties may pose a
threat to the environment and to human beings. For
instance, Diesel nanoparticles have been found to damage
the cardiovascular system in a mouse model.
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Sub-specialty of particle toxicology. It addresses the
toxicology of nanoparticles (particles <100 nm diameter)
which appear to have toxicity effects that are unusual and not
seen with larger particles
Typical nanoparticles that have been studied are titanium
dioxide, alumina, zinc oxide, carbon black, and carbon
nanotubes, and "nano-C60"
Seem to have some different properties from larger particles
that are known to have pathogenic effects
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These differences seem to be a result of their size.
Nanoparticles have much larger surface area to unit mass
ratios which in some cases may lead to greater proinflammatory effects (in, for example, lung tissue). In addition
nanoparticles seem to be able to translocate from their site of
deposition to distant sites such as the blood and the brain.
resulted in a sea-change in how particle toxicology is viewedinstead of being confined to the lungs, nanoparticle
toxicologists study the brain, blood, liver, skin and gut.
Nanotoxicology has revolutionised particle toxicology and
rejuvenated it.
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http://en.wikipedia.org/wiki/Nanomaterials
http://www.nicnas.gov.au/publications/informatio
n_sheets/general_information_sheets/nis_nanomat
erials_pdf.pdf
http://en.wikipedia.org/wiki/Colloidal_gold
http://en.wikipedia.org/wiki/Silver_nanoparticles
www.personal.rdg.ac.uk/~scsharip/tubes.htm