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Nanoparticles and nanotechnology
The scale of nanoparticles
Nanotechnology involves the study and use of extremely small substances, these are often called nanoparticles.
This technology uses substances that are on the scale of a nanometre. A nanometre is extremely small and is equivalent to:
1 x 10 -9
That is one thousandth millionth of a metre (1/1000,000,000 of a metre)
Or
1 millionth of a millimetre
The nanometre is abbreviated to nm and nanoparticles are very small, less than 100 nm across.
Uses of nanoparticles in the past
Nanotechnology has been used in the past e.g. nanoparticles of gold and silver were used in the 10 century to colour ceramics and stain glass.
Nanoparticles used in nature
Examples of nanoparticles in nature include:
- Insects and lizards are able to stick to walls because of the nanostructures on their feet
- Spiders’ webs are made of super-strong nanofibres
- Butterflies’ wings contain shiny reflective nanocrystals
This science tries to copy nature to make new useful nanochemicals.
The development of nanotechnology
In 1981 a new type of microscope called the scanning tunnelling microscope was invented allowing scientists to see the nanoworld. It also allowed them to move atoms into place and make pictures or words.
Colours produced by nanoparticles
It has been found that nanoparticles interact differently with light. This depends on the size of the nanoparticle. Gold metal usually produces the colour gold but nanoparticles of gold in solution will appear red or blue. Small nanoparticels appear red whereas slightly larger ones appear blue.
Properties of nanoparticles
Nanoparticles have more atoms or molecules near their surface than larger particles. This means they are able to react more quickly because more atoms are in contact with the reactant compared to a larger particle.
Nanoparticles have a much bigger surface area to volume ratio compared to larger particles. This makes them extremely useful as catalysts which speed up the rate of a chemical reaction.
Use of nanoparticles in health
Sunscreen contains nanoparticles of zinc oxide and titanium oxide, which absorb and reflect harmful UV rays from the Sun.
These particles are so small that they are invisible on the skin. Before nanoparticles, the oxide particles were big enough to be seen, so the sunscreen looked white on skin.
Plasters and bandages can contain nanocrystals of silver, because it is toxic to bacteria. Silver can even be woven into athletes' socks to kill the bacteria that creates a smelly odour.
Use of nanoparticles in cleaning
Fabrics have been developed with nano-coatings, which repel liquid and resist stains.
Spillages on treated fabrics will not soak into the fabric, but form beads of liquid, which can simply be wiped away.
Windows that are self-cleaning have been developed by British scientists. How could self-cleaning windows work?
Exercise 1
1. Nanoparticles are usually measured on the scale of nanometres because they are so small. How big is a nanometre compared to a metre?
2. Have nanoparticles been used in the past, if so then provide an example.
3. What instrument invented in 1989 allowed scientists to locate and move individual atoms into a specific location to make shapes or letters?
4. State one important property of nanoparticles that makes them very useful because of their size compared to other larger particles.
5. State one method of making a nanoparticle.