Nanoparticles

• • Nanoparticles are between 1 and 100 nanometres in size and usually contain only a few hundred atoms
  • Atoms and simple molecules are around 100 times larger than this
• • three categories according to their diameter:
  • Coarse particles (also called particulate-matter or dust)
  • Fine particles
  • Nanoparticles
• Nano particles are smaller than fine particles which have diameters between 100 and 2500nm ( nanometres)
• Coarse particles have diameters between 1 x 10 to the power of -5 metres and 2.5 x 10 to the power of -6 metres
• 1 nanometre = 1 x 10-9 m
• • As particles decrease in size, their surface area increases in relation to their volume
  • As the side of a cube decreases by a factor of 10, the surface area to volume ratio increases by a factor of 10
  • This is why nanoparticles may have properties different from the same materials in bulk
  • It may also mean that smaller quantities are needed to be effective than for materials with larger particle sizes
• • The main industrial application of nanoparticles is in catalysis due to their high surface area to volume ratios
• • nanoparticles are used in medicine and drug design as they are more easily absorbed than other particles and can deliver drugs to target areas more effectively
• • Nanoparticles of silver are sprayed onto the fibres of medical clothing. Silver Nanoparticles have nanoparticles have antibacterial properties, which help reduce the risk of infections. The high surface area of nanoparticles allows them to be very effective in killing bacteria or preventing their growth when applied in small quantities, making them suitable for use in healthcare settings .
• • nanoparticles are also used in electronic circuitry and as coatings for artificial limbs and joints
• • Silver nanoparticle coated clothing can act as a built in deodorant for clothing
• Advantages of nanoparticles

  • Nanoparticles have widespread uses and applications that can provide an immense advance in materials technology
• Disadvantages of nanoparticles

  • The use of nanoparticles in science is in its early stages so there are still a lot of unknown factors and potential risks - In particular there is a lack of understanding on how they may affect health
  • Even a small amount of toxicity in a particular nanoparticle would be multiplied due to the high surface area to volume ratio - This coupled with the fact that they are not easily disposed of by the body are a cause for caution in the medical application of nanoparticles
• • Titanium dioxide in nanoparticle form is used in sunscreens as it blocks UV light but leaves no white marks on the skin while also providing better coverage than other suncreams
  • The same chemical in bulk form is used as a white pigment in paints