Iron oxide nanoparticles
Iron is an element that, in its bulk form, is used in such everyday
settings as stair railings and the structural beams in cars or
buildings. Iron is also present in water and in our bloodstream, where
it helps to transport oxygen. Iron is one of the materials that we can
use to make magnets due to the way electrons orbit each atom. And, as we
all know, iron rusts when you combine iron and oxygen to form iron
oxide. It turns out that nanoparticles of both iron and iron oxide can
be quite useful.
If iron is left in the rain it will rust, and rust is composed of
iron oxide, a molecule that contains three atoms of iron and four atoms
of oxygen. Like iron, iron oxide has magnetic properties. Iron has four
unpaired electrons, whereas iron oxide has only two unpaired electrons.
Because the unpaired electrons make a material magnetic, iron oxide is
less magnetic than iron. Iron oxide is therefore called a paramagnetic
material. The paramagnetic properties of iron oxide nanoparticles are
not changed from the bulk material except that these tiny particles can
go where larger particles never could.
For example, in magnetic resonance imaging (MRI), you get a better
image if paramagnetic nanoparticles are attached to the object you’re
taking an image of. For that reason, researchers are functionalizing
iron oxide nanoparticles by coating them with molecules that are
attracted to cancer tumors to provide a better MRI image.
Making nanoparticles that have a core made of iron oxide nanocrystals
surrounded by nanoporous silica can improve not only the MRI images of
tumors but also give researchers control over the release of therapeutic
drugs. We discuss how nanotechnology is improving drug delivery in
A problem for tens of millions of people around the world is the
presence of arsenic, a naturally occurring substance in soil that can
dissolve in water, including well water. Robert Bunsen, the developer of
the Bunsen burner, which most of us encountered in our high school
science labs, determined in the 1830s that when you mix ferric oxide
with arsenic, you get a potion that both the fluids in your body and
water cannot break down. Based on Bunsen’s discovery, scientists started
using iron oxide in filters to remove arsenic from water.
Excerpted from Nanotechnology For Dummies (2nd
edition), from Wiley Publishing