Extreme Physics -Very Small Things

Extreme Physics
Done by: Foo Kai Siang: 3A311
Introduction-What are nanoparticles?
There is no accepted international definition of a
 However, one given in the UK is: "A particle having
one or more dimensions of the order of 100nm or
 There is a note associated with this definition: "Novel
properties that differentiate nanoparticles from
the bulk material typically develop at a critical length
scale of under 100nm".
Why are they different
The "novel properties" mentioned are entirely
dependent on the fact that at the nano-scale.
 The physics of nanoparticles mean that their
properties are different from the properties of the
bulk material.
 This makes the size of particles or the scale of its
features the most important attribute of
 Thus, it can be said that nanoparticles are different
because they are ‘small’
Why are they different
There is no strict dividing line between
nanoparticles and non-nanoparticles.
The properties of many conventional materials
change when formed from nanoparticles. This is
typically because nanoparticles have a greater
surface area per weight than larger particles;
this causes them to be more reactive to certain
other molecules.
Case Study: Gold Nanoparticles
We all know that Gold is very shiny when in its
natural state.
However, the formation of gold nanoparticles can
be observed by a change in colour since small
nanoparticles of gold are red.
Case Study: Gold Nanoparticles
A layer of absorbed citrate anions on the surface of
the nanoparticles keep the nanoparticles separated.
The presence of this colloidal suspension can be
detected by the reflection of a laser beam from the
Switching to a smaller anion allows the particles to
approach more closely and another color change is
Thus, gold nanoparticles can be many different
colours, red, blue, yellow, depending on its size.
Case Study: Gold Nanoparticles
As mentioned previously, nanoparticles are more
reactive to certain other molecules than bulk particles
Applying this theory in the case of Gold nanoparticles,
the bulk particles of gold that we see today are not
reactive to the citrate anions as they do not have such
a large surface area per weight ratio.
Thus, without the citrate anions giving off the red
colour under the microscope, bulk gold particles that
we know today are shiny and glittery
Technological Applications
Manufacture of stain-resistant fabrics
 Solar panels
 Lightweight bulletproof military vest
 Therapy against Heart Disease
 Imaging agents
Stain-Resistant Fabric
Making composite fabric with nano-sized particles
or fibers allows improvement of fabric properties
without a significant increase in weight, thickness,
or stiffness as might have been the case with
previously-used techniques.
For example incorporating nano-whiskers into
fabric used to make pants produces a lightweight
water and stain repellent material.
Nanoparticles can cause water to bead up, making
the fabric water and stain resistant
Stain Resistant Fabric
More examples are:
1. Silver nanoparticles in fabric that kills bacteria
making clothing odor- resistant.
2. Nanopores providing superior insulation for shoe
inserts in cold weather.
3. Nanoparticles that provide a "lotus plant" effect
for fabric used awnings and other material left out
in the weather, causing dirt to rinse off in the rain.
Solar Panels
Scientists are developing a relatively new
approach to solar cells: lacing them with
nanoscopic metal particles.
As the authors describe in a new article, this
approach has the potential to greatly
improve the ability of solar cells to harvest
light efficiently.
Solar Panels
Current solar cells cannot convert all the
incoming light into usable energy because
some of the light can escape back out of
the cell into the air.
 Additionally, sunlight comes in a variety of
colours and the cell might not be efficient
in converting all light forms
Solar Panels
The nanoparticle approach seeks to remedy these
The key to this new research is the creation of a tiny
electrical disturbance called a "surface plasmon."
First of all, the use of nanoparticles causes the
incoming sunlight to scatter more fully, keeping more
of the light inside the solar cell.
Second, varying the size and material of the particles
allows researchers to improve light capture at
otherwise poorly-performing colors.
Light, Bulletproof Military Vest
Liquid armor has been shown to stop bullets
more effectively than plain Kevlar, according to
British firm BAE Systems. The material could be
used to make thinner, lighter armor for military
personnel and police officers,
 Materials scientists combined a shear-thickening
liquid with traditional Kevlar to make a
bulletproof material that absorbs the force of a
bullet strike by becoming thicker and stickier.
Light, Bulletproof Military Vest
Its molecules lock together more tightly when it is
struck, the scientists explained -- they described it
as "bulletproof custard,"
Shear-thickening liquids are composed of hard
nanoparticles suspended in a liquid, which turns
rigid after being struck with a bullet or shrapnel.
BAE says their tests provide the first clear evidence
that it can actually protect people.
Light, Bulletproof Military Vest
In some tests, BAE scientists used a gas gun to fire
ball-bearing bullets at nearly 1,000 feet per second
at two test materials -- 31 layers of regular Kevlar
and 10 layers of Kevlar combined with the shearthickening liquid.
The shear-thickening liquid stopped the bullets
more quickly and prevented them from penetrating
as deeply, showing that the nanoparticles in the
‘liquid armour’ is indeed effective.
Therapy Against Heart Disease
Researchers at MIT and Harvard Medical School
have built targeted nanoparticles that can cling to
artery walls and slowly release medicine.
It is an advance that potentially provides an
alternative to drug-releasing stents in some patients
with cardiovascular disease.
The particles, dubbed “nanoburrs” because they are
coated with tiny protein fragments that allow them
to stick to target proteins, can be designed to
release their drug payload over several days.
Therapy Against Heart Disease
They are one of the first such targeted particles that
can precisely home in on damaged vascular tissue
The nanoburrs are targeted to a specific structure,
known as the basement membrane, which lines the
arterial walls and is only exposed when those walls
are damaged.
Therefore, the nanoburrs could be used to deliver
drugs to treat atherosclerosis and other inflammatory
cardiovascular diseases.
Imaging Agents
Hybrid nanoparticles which incorporate
multiple functionalities, such as fluorescence and
magnetism, can exhibit enhanced efficiency and
versatility by performing several tasks in parallel.
 In this study, magnetic-fluorescent
semiconductor polymer nanospheres (MFSPNs) have been synthesized by encapsulation
of hydrophobic conjugated polymers and iron
oxide nanoparticles in phospholipid micelles.
Imaging Agents
Four fluorescent conjugated polymers were
used, yielding aqueous dispersions of
nanoparticles which emit across the visible
 In MRI studies, they were seen to have a
shortening effect on the transverse relaxation
time, which demonstrates their potential as an
MR contrast agent.
Imaging Agents
Finally, successful uptake of the MF-SPNs
by SH-SY5Y neuroblastoma cells was
demonstrated, and they were seen to
behave as bright and stable fluorescent
 There was no evidence of toxicity or
adverse affect on cell growth.
Some Video links
 http://www.youtube.com/watch?v=uyhxRI
Nanoparticles are small substances which are
different than its bigger form.
Nanoparticles are really useful in the advancement
of modern technology and are really important to
They could be our basis for the next big human
technology breakthrough and it will be important
for us to do more research on it as can be seen
from the examples above, we are not really quite
done with Nanoparticles just yet.
I feel that it is really a great and enriching
experience learning about such a fascinating topic.
I started doing this topic as an ACE assignment but
felt a little sad when I actually finished it in the end.
This is really a field of technology in which people
and scientists can focus on in the future to create
better and more efficient technology to enhance
and improve the lives of the people of the world.
I have also gained much more insight on this topic.
Thank You
Any Questions??

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