Nano-scale particles
A nano-scale particle is a particle of a substance that is 1 鈥 100 nm in diameter (1 nm = 1 nanometre = 1 脳 10鈥9 m, which is one billionth of a metre). Nano-scale particles have very different properties from the 鈥榥ormal鈥 form of the substances. For example, nano-scale particles of silver are very good at killing bacteria and viruses.
Nano-silver is used:
- in wound dressings to prevent infection
- to coat the inside of socks and the inside of fridges to kill the bacteria that cause bad smells
- in deodorants to kill bacteria that cause bad smells
- to disinfect water supplies on the International Space Station
Bulk silver does not have any of these properties. It is a shiny metal that doesn鈥檛 corrode, and so its main use is in jewellery.
Nano-scale particles of titanium dioxide can be used in sunscreen to block harmful ultraviolet light. This helps to prevent sunburn and skin cancer. These particles are so small that they cannot be seen and so make the sunscreen invisible. Titanium dioxide nanoparticles can also be used in self-cleaning windows, as they can break down the dirt on the surface of the windows.