Brown's Chemistry Revision Notes NANOCHEMISTRY
Nanoscience - Nanotechnology - Nanostructures
Uses of nanoparticles of titanium(IV) oxide, fat & silver
Alphabetical keyword index for
the nanoscience pages : Index of nanoscience pages
: boron nitride *
Buckminsterfullerenes-bucky balls *
carbon nanotubes * fat nanoparticles
* fluorographene *
graphene * health and
* liposomes *
nanoscale * nanoscience *
* nanotechnology *
problems in nanomaterial use *
silver nanoparticles *
safety issues * sunscreens-sunblockers *
Uses of nanoparticles of titanium(IV) oxide (titanium dioxide,
Nanoparticles are used in sun creams
because they are more effective than traditional sun cream formulations for
protecting the skin from the effects of uv light rays.
They are also more efficient in
covering the skin, less needed, but there is concern as to whether the
nanoparticles can be absorbed into the body and
How does titanium dioxide
protect us from uv light? What does titanium dioxide do in sun creams?
In the cosmetics industry the use of nanosized particles in creams etc is increasing,
because of the small particle size, they can be more easily absorbed
through the skin, as in moisturisers.
Titanium dioxide, TiO2, is a white
powder and a good reflector of visible light and most commonly encountered as a brilliant white pigment in paint.
However, it also used in the
cosmetic and skincare products industry as a pigment, thickener, moisturiser
and used in sunscreens as a uv absorber.
Ultraviolet light from the sun
impacting on the skin can cause cell damage, e.g. DNA damage, which can lead to
Nanoparticles used in sun creams offer
better skin protection than traditional uv sun blocker creams and less
is needed to cover the same surface area of skin.
In sun creams nanoparticles provide
better protection from the harmful effects of ultraviolet radiation (uv rays
from the sun) and give better coverage of the skin.
Titanium dioxide is a good uv
light absorber and is effective as many organic molecules used as uv
absorbers in many commercial sun creams.
Some of these organic 'sun blocker'
molecules can cause skin irritations on sensitive skin. Can the
nanoparticles be absorbed by the skin and cause this irritation or other
Nanoparticles of titanium
dioxide are incorporated into 'sun blockers', though the particles have to
be specially coated (*) to avoid skin irritation problems from using
such titanium dioxide based sunscreens.
As well as being a good uv
absorber (90% absorbed, 10% scattered), nanosized titanium dioxide particles have
2nd another advantage.
TiO2 particles are smaller than
the wavelength of light and are therefore too small to see, and when used
in sunscreen creams they are transparent to light rather than opaque, so the
skin looks a more natural colour (no white creamy marks), so nanochemistry
can satisfy aspects of human aesthetics (or vanity!).
The wavelength of visible light
ranges from 300 to 700 nm.
The nanoparticles of TiO2
typically used vary from 20 to 170 nm in size.
A good example of where particle
size matters, and the tiny size of titanium dioxide particles gives it this
Note in passing that
nanoparticles of zinc oxide are also used in sunscreens with the similar
properties and effects.
Note - titanium dioxide in the
form of anatase crystals can be converted into nanotubes 10-20 nm in
diameter - but I don't know their potential uses?
What are nanoparticles of
silver? What size are they? What can we do with nanoparticles of silver?
Silver has always been used as a
catalyst to speed up specific reactions in the chemical industry to improve
By using nanoparticles of silver (35-120 nm in size)
the effectiveness of the catalyst is greatly improved because the surface
area of nanosized silver is so much greater than the larger particles
Its a good example of the 'surface area' rates-kinetic
factor for reactions involving a solid catalyst or reactant and silver
nanoparticles are extremely effective in killing bacteria.
Larger particles of silver, with
a lower surface/volume ratio, have no effect on bacteria.
Nanoparticles of silver have very good
Nanoparticles of silver are
being used in anti-bacterial and anti-fungal agents in biotechnology,
bioengineering, the textile industry, water treatment and disinfecting
surfaces in the home or hospitals etc.
Bactericide and fungicide
formulations are being developed to include nanoparticles e.g. of silver,
because of their powerful ability to kill bacteria and other organisms.
Because of their antibacterial
and antifungal properties, potential uses of silver nanoparticles include
bone cement, surgical instruments, surgical masks and wound dressings.
In other words you can fabricate
materials e.g. from plastic fibres, with built in silver nanoparticles, to
keep them sterile (enhanced antibacterial life) even after application to
A wide variety of fabrics in medical,
domestic or outdoor use can be treated with nanoparticles (e.g. of silver)
to inhibit the growth of bacteria.
You can add antibacterial nanoparticles
of silver to polymer fibres used in surgical masks and wound dressings.
Nanoparticles of silver can be used in
deodorants, but can they do us harm if breathed in?
There is an advantage (at least
at the moment!) in using nanoparticles of silver in antibacterial agents,
because many bacteria are evolving into strains which are resistant to many
antibiotics rendering the ineffective in fighting infections, but so far
bacteria don't seem to be resistant to nano-silver formulations!
Nanoparticles of silver are also
used in optics and electronics - important applications but not much, if
any, chemistry involved?
fat are used in cosmetics
Some cosmetics contain 'liposomes',
which are fatty nanoparticles.
Nanoparticles of fatty-like
molecules have great potential in the pharmaceutical
industry to deliver tiny doses of medicines directly into cells.
Other examples of the use of nanoparticles and
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NANOSCIENCE - NANOCHEMISTRY INDEX
General introduction to nanoscience,
and commonly used terms explained
NANOCHEMISTRY - an introduction and potential
applications including catalysts
Uses of Nanoparticles of titanium(IV) oxide, fat and silver
From fullerenes & bucky balls to carbon nanotubes
graphene oxide and
Cubic and hexagonal boron nitride BN
Problems, issues and
implications associated with
see also INDEX
SMART MATERIALS PAGES
Keywords: uses applications
liposomes fat sunscreens-sunblockers titanium dioxide silver nanoparticles TiO2
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