Figure 13.

Schematic illustration of skin layers and major skin permeation routes for the delivery of nanoparticles. The first one is the pathway through opening areas of the skin such as sweat glands and hair follicles which leads to a better penetration of the drugs into the skin. Drug molecules diffuse through the phospholipid membranes and cytoplasm of the deceased keratinocytes. In this continuous way bioactive agents pass through the small spaces between the cells of the skin.