Titanium Dioxide Nanoparticles
Titanium dioxide is a molecule composed of one atom of titanium and
two atoms of oxygen. Titanium dioxide absorbs ultraviolet light; this
property makes titanium dioxide useful in sunscreens.
Titanium dioxide nanoparticles are photocatalysts, which means that
they have the capability to use energy in light to catalyze reactions
with other molecules at reduced temperatures. Although other
photocatalytic materials are available, researchers have found that
titanium dioxide provides the best performance in sunlight.
Another property of titanium dioxide is that it reflects all colors
in the visible light spectrum, therefore the light reflected from
titanium dioxide is white. This characteristic makes it useful as a
white pigment in paints and may make for white residue on your skin when
you slather on sunscreen.
Forming titanium dioxide nanoparticles allow researchers to form
photocatalysts that are more effective because they have more surface
area available to react with other molecules. Also, in the nanoparticle
form, titanium dioxide can be used in creams and coatings that absorb UV
without causing a white coating.
Note that titanium dioxide (a molecule composed of one atom of
titanium and two atoms of oxygen) nanotubes are similar to carbon
nanotubes in that they are hollow cylinders. But titanium dioxide
nanotubes, instead of being composed of carbon atoms bonded together,
are made up of titanium dioxide molecules bonding together to form the
surface of a cylinder. The oxygen atoms bond to another titanium atom,
and you end up with a cylindrical lattice in which each oxygen atom is
bonded to two titanium atoms. This arrangement of oxygen atoms between
each titanium atom results in a much more complicated nanotube
Some companies use titanium oxide nanoparticles as part of a film
that uses the energy in light to start the chemical reaction that kills
bacteria on surfaces.
At Penn State, a team of researchers led by Craig Grimes has come up
with an ingenious method of turning captured CO2 into methane. They use
clusters of titanium dioxide nanotubes coated with a catalyst that helps
convert carbon dioxide and water into methane using sunlight as the
Researchers are also developing methods to use the photocatalytic
properties of titanium dioxide nanoparticles to destroy cancer tumors.
They are delivering titanium dioxide nanoparticles to cancer tumors
using targeted drug delivery methods, then shining light on the tumor.
The titanium dioxide nanoparticles use the energy from the light to add
an electron to oxygen molecules, which proceed to destroy cancer cells.
Excerpted from Nanotechnology For Dummies (2nd edition), from Wiley Publishing