Nanoparticles: uses and hazards

In a nutshell

Nanoparticles are particles which are very tiny with a diameter between $1 \,nm$ and $100 \,nm$ . This is the same as being between $1\times10^{-9} \,m$ and $1\times10^{-7} \,m$ .

Surface area to volume ratio

The surface area to volume ratio is a way of representing how large the surface area is in comparison to volume. As the particle gets larger, the volume increases at a faster rate than their surface area. So, larger particles have a smaller surface area to volume ratio. This means that the surface area to volume ratio for nanoparticles is large. This means less material is required to work effectively compared to a larger material. This makes them useful as catalysts. This is shown in the table below.

Example

Particle
Surface area	$1\times 1\times 6=6\ cm^2$	$2\times 2\times 6=24\ cm^2$	$3\times 3\times 6= 54\ cm^2$
Volume	$1\times 1\times 1=1\ cm^3$	$2\times 2\times 2=8\ cm^3$	$3\times 3\times 3=27\ cm^3$
Surface area to volume ratio	$\frac{6}{1}=6:1$	$\frac{24}{8}=3:1$	$\frac{54}{27}=2:1$

Uses of nanoparticles

Nanoparticles have a wide variety of uses. These are described below.

Use	Description
Nanomedicine	Nanoparticles are very small so they may be able to deliver drugs more effectively than normal sized particles.
Electrical conductor	Nanoparticles can be used in computer chips as they are very small.
Cosmetics	Nanoparticles have been used in moisturisers without making them oily.
Sun cream	Nanoparticles absorb UV light but are not seen on the skin.
Medical applications	Silver nanoparticles have antibacterial properties so they can be used in medical equipment like surgical masks.
Catalysts	Nanoparticles make good catalysts as you will need less of the material to have the same effect.

Hazards

The full impact of nanoparticles is unknown and further research needs to be done regarding the effects of nanoparticles on the human body. However, it is possible that they can take a long time to break down and they could easily be breathed in or absorbed through the skin. The consequences of this are unknown.