Nanoparticles

Here’s a page about very tiny particles. Please note that this is only included on the triple science specification for certain exam boards.

Sizes of particles

Nanoscience is the study of particles which are extremely small (between 1 - 100 nanometres in size). These are called nanoparticles and are typically made up of a few hundred atoms. Here’s how the size of nanoparticles compared to other types of particles:

• Nanoparticles: 1 - 100 nm

• Fine particles: 100 – 2500 nm (1 x 10-7 m and 2.5 x 10-6 m

• Coarse particles: 1 x 10-5 m and 2.5 x 10-6 m (these particles are often referred to as dust)

Nanoparticles have very high surface area to volume ratios compared to the same material in bulk or powdered form. The smaller the nanoparticles, the larger its surface area. For a nanoparticle cube, as the side of the cube decreases by a factor of 10, the surface area to volume ratio increases by a factor of 10. This means that smaller quantities of nanoparticles are needed to be effective compared to materials made up of larger particles.

Uses of nanoparticles

Nanoparticles have several uses:

• Medicine – in MRI scanning and cancer therapies

• Electronics – used in memory chips and transistors in electrical circuits

• Cosmetics – nanoparticles are used in skin care lotions to encapsulate nutrients within a liquid

• Sun cream – nanoparticles have replaced zinc oxide (a white solid) to manufacture transparent sun creams

• Deodorant – silver nanoparticles have antibacterial properties. Killing bacteria on the armpit prevents body odour.

• Catalysts - self-cleaning window panes have nanoparticulate coatings. These catalyse the breakdown of dirt in the presence of sunlight.

Research is being carried out to find new applications for nanoparticulate materials. However, there are risks associated with the use of nanoparticles. For example, due to their size it is thought that they can be easily inhaled. Once they are inside the body they could act as catalysts, triggering unwanted chemical reactions. Nanoparticles are a fairly new area of science and scientists have not fully assessed their potential risks.