London: Researchers have found that even the most expensive cosmetic creams cannot `penetrate` the skin to repair it from within as claimed by manufacturers.
Scientists at the University of Bath found that claims by pharmaceutical brands that nanoparticles in their products give their creams a `deep penetrating action` are `patently` untrue.
Even the tiniest of nanoparticles do not penetrate the skin`s surface, creams are simply deposited into creases in the skin and do not carry nutrients deep under the surface, the study found.
"Whereas earlier work has suggested that nanoparticles appear to penetrate the skin, our results indicate that they may in fact have simply been deposited into a deep crease within the skin sample," Professor Richard Guy, a professor of Pharmaceutical Sciences who led the research, said.
"The skin`s role is to act as a barrier to potentially dangerous chemicals and to reduce water loss from the body. Our study shows that it is doing a good job of this," Guy said.
"So, while an unsuspecting consumer may draw the conclusion that nanoparticles in their skin creams, are `carrying` an active ingredient deep into the skin, our research shows this is patently not the case," Guy was quoted as saying by the paper.
Researchers studied particles less than one hundredth of the thickness of a human hair which are used in sunscreens and some cosmetic and pharmaceutical creams.
They used a technique called laser scanning confocal microscopy to examine whether fluorescently-tagged polystyrene beads, ranging in size from 20 to 200 nanometres, were absorbed into the skin.
The study found that even when the skin sample had been partially compromised by stripping away layers, the nanoparticles still did not penetrate the skin?s outer layer, known as the stratum corneum.
"We did the study very carefully but not once we were able to determine that that were able to cross the outside layer of the skin which is out protective layer," Guy said.
"There is no magic associated with particles being able to wriggle across the skin, they are just too big to do that. We actually have lots of nanoparticles inside us that don`t get out," he added.
He said that the research did however help to prove that potentially harmful ingredients, such as those used in sunscreens, can not be absorbed into the body, alleviating fears.
The research was published in the Journal of Controlled Release.