Firms selling skin creams, cosmetic products and suntan lotions that claim they are able to transport their active ingredients deep into the skin using ‘nanoparticles’ don’t actually work, according to a new study by West scientists.
The research, by scientists at the University of Bath, challenges the claims that are the current popular trend in TV adverts for everything from cream that claims to ‘lift’ the face’s features to sun lotion that claims it can protect deeper layers of the skin.
The adverts and products claim they contain nanoparticles, which are tiny particles less than one-hundredth of the thickness of a human hair, which can penetrate the skin’s outer layers and take with them the ‘active ingredients’ the cream or lotion contains.
But the Bath scientists found this was not true – nanoparticles did not penetrate the skin’s surface, even if you strip away the top layers of skin using sticky tape before you put the cream on.
Diplomatically, the researchers said their findings had ‘implications’ for pharmaceutical researchers and cosmetic companies that design skin creams ‘with nanoparticles that are supposed to transport ingredients to the deeper layers of the skin’.
But the researchers did say that their findings should reassure people worried about the potentially harmful nanoparticles in things like suncream, which had been a source of safety concerns.
Prof Richard Guy, from Bath’s department of pharmacy and pharmacology, led the study, which laser scanned fluorescently tagged polystyrene beads, which ranged in size from 20 to 200 nanometres.
The beads were so small, you would need 500,000 of the smallest ones to fill a centimetre wide space.
And Prof Guy found that even the smallest did not get anywhere near penetrating the skin; even when the skin sample had its outer layers stripped with adhesive tape, these nanoparticles did not penetrate it.
“Previous studies have reached conflicting conclusions over whether nanoparticles can penetrate the skin or not,” he said.
“Using confocal microscopy has allowed us to unambiguously visualise and objectively assess what happens to nanoparticles on an uneven skin surface.
“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.
“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.
“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.”
The results of the work, published in the Journal of Controlled Release, suggest that it might be possible to design a new type of nanoparticle-based drug formulation that can be applied to the skin and give controlled release of a drug over a long period of time.
This would enable sustained delivery of the active drug, potentially reducing the frequency with which the patient would have to apply the formulation to the skin.