The skin serves as a barrier that protects the body from the external environment and prevents water loss. This barrier function also prevents most hydrophilic or hydrophobic and large molecular weight ingredients (>；500 kDa) from penetrating intact skin. Until recently, methods to increase stratum corneum permeability were generally not effective enough to make the stratum corneum so permeable that the barrier posed by the viable epidermis mattered. However, that has now changed with the development of the present embodiment's physical methods and highly optimized chemical formulations, such that we revisited the permeability of the full epidermis with the example embodiment's constructs and not focus only on the stratum corneum. This example embodiment therefore tests the hypothesis that the viable epidermis offers a significant permeability barrier to both small molecules and macromolecules that becomes the rate limiting step.
