Wednesday, April 24, 2013

Nanoparticles: Engineering at the Molecular Level

A nanometer (nm) is one billionth of a meter or one thousandth of a micron. The scale in the picture ranges from 0.1 nm (atoms), to 1-100 nm (molecules), to 1000 nm (bacteria and cells). 1000 nm equals 1 micron (1 um). A glucose molecule has a diameter of 1 nm, and a hemoglobin molecule has a diameter of 6 nm. Breathing, eating, and other physiological functions depend upon the interactions of biomolecules, that is, nanoparticles. All cellular biochemistry takes place on the nanometer scale.

The human body has been dealing with nanoparticles (NP) since the beginning. Many ultrafine particles such as fine sand, smoke, diesel fumes, furnace emissions, and welding fumes have diameters in nanometers; these are natural or man-made nanoparticles.

So, why the concern about the safety of engineered nanoparticles? These particles are synthesized intentionally, and generally have a size of between 1 and 100 nm. Compared to larger particles, NP have increased surface area and unique properties such as conductivity, strength, and chemical reactivity. Dust explosions are a potential hazard. According to the IRSST in Quebec, Canada, the engineered nanoparticles of most concern are the long, thin carbon nanotubes and NP that do not dissolve in solution. ". . . the majority of the means of exposure control for ultrafine particles should be effective against NP and much research is currently being carried out to confirm this." There is less concern with older technologies such as microelectronics where "risks are adequately controlled." Now is the time for prevention, "since prevention and monitoring can be carried out at the design and implementation stages of a number of processes."