What is Nano Chemistry?

In the last few years, due to extensive research undertaken by scientists all over the world,
there have been significant breakthroughs in nanoscience technology. The word ‘nano’
comes from the word ‘nanos’ in Greek. It represents a billionth fraction of a unit.

Nano chemistry is a branch of nanoscience and a relatively new branch of chemistry. It
deals with the chemical applications of nanomaterials in nanotechnology. More specifically,
nano chemistry is a branch of nanoscience which is concerned with the utilization of
synthetic chemistry to make nanoscale building blocks of different sizes, shapes,
composition, surface structures, charge and functionality.

Nano chemistry encompasses the special properties that are associated with assemblies of
molecules or atoms at the nanoscale (1-100 nm), so the size of nanoparticles is bigger than
atoms or molecules yet smaller than larger assemblies of molecules (bulk material) which
we deal with more frequently.

Nano Structures

At the extremely small-scale level of nano structures (1-100 nm), quantum effects can be
exploited to carry out chemical reactions in beneficial ways. This is because the small size of
nanoparticles gives these particles ‘unusual’ structural and optical properties with mean
they have applications in wide range of technological fields.

Nanoparticles are very small aggregations of atoms, however they are still usually bigger
than most molecules. That said, there is no strict dividing line between nanoparticles and
‘ordinary bulk’ particles of a material such as baking powder or grains of sand. The number
of particles is very important though because nanoparticles can display properties
significantly different from the bulk material and these properties can be exploited for many
different uses.

Why do nanoparticles exhibit such properties?

The fact that they are so small means that nanoparticles have a high surface to volume
ratio which has a dramatic effect on their properties compared to non-nanoscale, more
bulky forms of the same material. It gives them extra chemical reactivity compared to the bulk material. This means less of a material like a catalyst is needed in a chemical process,
so catalysts based on nanoparticles are more efficient than those based on bulk material.

Silicon Nanoparticles (Credits: SkySpring Nanomaterials)

Medical Applications

Sunscreen:

Sunscreen contains nano particles of titanium dioxide. On a bulk scale, titanium dioxide is a
white solid used in house paint where it reflects visible light and can therefore be seen. This
is why sunscreen looks white when you first open it and put it on your hand before you
smear it on your skin. However, once smeared, the sunscreen’s white colour disappears,
and it loses its colour if the right amount of it has been administered.

The reason for this is that titanium dioxide nano particles are so small that they do not
reflect visible light and thus they cannot be seen. They do however protect the skin against harmful UV light by reflecting or absorbing the light and preventing it from damaging the
skin. They do this by a process called photo-excitation which happens on a quantum level.
Titanium dioxide particles are more stable, requiring less reapplication, and are low irritant
and low allergen materials which makes them ideal for use in sunscreen.

Drug delivery:

Nanotechnology has recently been making breakthroughs in drug delivery. Drug delivery on
a nano scale may be advantageous since it can be less toxic, more specific and can
react better with the body. One recent area of drug delivery where nanoscience has been
making a breakthrough is in the fight against cancer. Scientists are using cells
isolated from human tumours to develop new ways to tackle cancer. For most drugs to be
active, they must go inside a cancer cell. Scientists are developing nanoparticles that can be
loaded with drugs. The nanoparticles can be modified so that they attach to the cancer cell
and get carried inside. To make sure that the drug-loaded nanoparticles only attack the
diseased cells, they are engineered so that they only bind to the cancer cells and not to the
healthy neighbouring cells. Once they bind, they are taken inside the cancer cell,
where they kill it. Nanoparticle based drug delivery provides a way of attacking cancer
without the toxic side effects of conventional chemotherapy. The image below shows
gold nanoparticles being used to treat cancer:

Credits: Onco’Zine

Regenerative Medicine:

There are several areas of regenerative medicine where nano-chemistry is being, and can be,
applied. Scientists are creating materials with nanotechnology to mimic the crystal mineral
structure of human bone and they’re creating materials which can be used as a restorative
resin for dental applications. They’re also trying to find ways to artificially grow complex
tissues with the goal of one day growing human organs for transplant, and they’re
implementing nano chemistry to help them. Researchers have created a nanoparticle that
mimics the body’s good cholesterol, known as HDL or high-density lipoprotein, which helps
to prevent the build-up of plaque in arteries.

Engineering Applications

Improved Materials:

Many benefits of nanotechnology exist, since people can manipulate materials at the
nanoscale to achieve desirable properties. Using nanotechnology, materials can be
enhanced to be lighter, stronger and more durable, and to exhibit many other desirable traits.
Many things that we all use in our everyday lives utilize nanoscale materials and processes.
One example of this is in personal body armour, with Kevlar. Kevlar is bullet-proof body
armour. It’s an extremely strong plastic made by polymerization (joining together long chain
molecules). It’s extremely strong and durable due to its internal structure as the
molecules are naturally arranged in parallel and regular lines. When manufactured, it’s
made into fibers that are tightly knitted together which further improves strength.

Tightly knitted nano fibers (Credits: NanoWerk)

Environmental Applications

Carbon Nanotubes:

Researchers are working on making wires containing carbon nanotubes that’ll have a lower
resistance than the wires currently used in the electric grid, which would reduce power loss
and save energy. Carbon nanotubes are being used to make windmill blades that are longer,
stronger, and lighter-weight than other blades to increase the amount of electricity that
windmills can generate. Researchers are investigating carbon nanotube “scrubbers” to
separate carbon dioxide from power plant exhaust to reduce the greenhouse effect too.

Carbon Nanotube (Credits: Stanford University)

Water Treatment:

Nanotechnology has the potential to make clean drinking water accessible to all by quick
and inexpensive treatment of water. Scientists have developed a nano structure with nanopores for energy-efficient water treatment as shown below.

Water filtration device (Credits: Nature)

This molybdenum disulphide (MoS2) nano structure filtered 2-5 times more water than current conventional filters which we use today.

Nanoparticles are being developed which could potentially be released into dirty water
which would then react chemically and render toxic pollutants harmless. This would be a lot
cheaper and quicker than current methods used to treat toxic industrial waste.

Filtration and Environmental Cleaning:

Researchers have developed a nano-fabric woven from tiny wires of potassium manganese
oxide that can absorb 20 times its weight in oil for oil spill clean-ups. Furthermore, they’v
also managed to create magnetic water-repellent nanoparticles that can be used to remove
oil from water.

Air filters also use nanotechnology to perform mechanical filtration, in which nanoscale pores
trap particles larger than the size of the pores. The filters also may contain charcoal layers
that remove odours.

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