A nanotech solution to wrinkled skin
Kristina Kirby
09 January 2007
Chemistry World--Those of us unhappy with our ageing skin may find
solace in nanotechnology. Researchers who have discovered that
nanoparticles prevent thin polymer films from buckling say their
concept could be applied to stop human skin wrinkling too.
Nanoparticles are already marketed in cosmetic skin products; usually
because they can penetrate much deeper into skin than conventional
creams, delivering vitamins that are supposed to plump and soften the
skin, reducing wrinkling. The approach of Ilsoon Lee, of Michigan State
University, US, is somewhat different: nanoparticles in sufficient
concentration, he suggests, may stop the skin ever wrinkling in the
first place.
That's because the same underlying principles of wrinkling lie behind
human skin and the polymer film systems which Lee has been
investigating. Human skin, Lee says, consists of a thinner outer layer
(the epidermis, around 50-100 µm thick) resting on top of a thicker
layer (the dermis, around 1-3 mm thick). Similarly, thin polymer films
used to create anticorrosion, water-repelling, or biocompatible
surfaces, and also in electronic devices like thin film transistor
(TFT) screens, are formed on top of a thicker substrate - a flexible
plastic, for example.
Although skin is a living material, vastly more complicated than a
polymer film, Lee believes that both heated film and aged skin wrinkle
permanently because they stiffen up more than the soft plastic or
dermis below them. The same effect is seen in dried fruits, when thin
dried skin stiffens over a soft interior.
Lee and his colleague Troy Hendricks wanted to prevent polymer films
from buckling as they were compressed or heated during the
manufacturing process. Wrinkled films, Lee told Chemistry World, can be
a problem for electronic applications; for instance, the wrinkles can
approach the size of the increasingly small features printed on the
film, disrupting an electronic device's function.
The researchers found that 50 nm silica particles deposited in layers
through a thin polyelectrolyte film stopped the film from wrinkling up
when heated or compressed. Lee suggests that the particles work by
redistributing stress forces out of the plane of the film. The
nanoparticles might affect the film's performance, Lee conceded;
though in the case he tried, the film stayed transparent to light as
required. His group are testing different sorts of nanoparticles, of
varying size and shape, to see if they have the same anti-wrinkling
properties.
In themselves, said Geoffrey Ozin of the University of Toronto,
California, US, these results are 'extremely interesting and
scientifically surprising'. But Lee thinks that the same principles
could be applied in a cosmetic product or implantable device to stop
skin wrinkling too.
'We don't mean that people will literally bombard their skin with
nanoparticles,' Lee told Chemistry World (though he pointed out that
injecting a toxin, Botox, into one's skin to remove wrinkles also
sounds strange). Instead, he speculates that wrinkle-free film could be
sandwiched between protecting layers, to be used in artificial skins
for surgery, or implanted onto a face. Another route involves a topical
cream containing materials which act in human skin as the nanoparticles
behave in thin films.
There are obvious health and safety issues with such applications - the
nanoparticles will have to be cleared for toxicity. Nor may Lee's
technique be generally applicable, if skin doesn't behave in the same
way as thin films do. But it's an intriguing possibility: one more
cosmetic spin-off to add to nanotech's lengthening list.
Richard Van Noorden
http://www.rsc.org/chemistryworld/News/2007/January/09010602.asp