Research by scientists at the University of Bath, UK, is challenging claims that nanoparticles in medicated and cosmetic creams are able to transport and deliver active ingredients deep inside the skin.
The Bath study discovered that even the tiniest of nanoparticles did not penetrate the skin’s surface. These findings have 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. However the findings will also allay safety concerns that potentially harmful nanoparticles such as those used in sunscreens can be absorbed into the body. The scientists used a technique called laser scanning confocal microscopy to examine whether fluorescently-tagged polystyrene beads, ranging in size from 20 to 200 nanometers, were absorbed into the skin. They found that even when the skin sample had been partially compromised by stripping the outer layers with adhesive tape, the nanoparticles did not penetrate the skin’s outer layer, the stratum corneum. 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.
