ABSTRACT
The skin is an information-rich interface that forms the foundation for multiple practical applications including drug delivery, adhesion, bathing, massage, and biomedical monitoring (1). In the future, it is foreseeable that such applications will be enhanced or enabled by the creative juxtaposition of selected cubosomal gel/polymer systems with the skin and/or mucosal surfaces (Table 3.1). The choice and design of such gel/polymer systems requires detailed understanding of the biological surfaces they encounter, specifically the electrical, chemical, mechanical, and thermal properties of the outermost portion
of the epidermis; i.e., the stratum corneum. In humans, the stratum corneum is constituted by a thin (
∼
20 microns thick), conformal, highly organized biopolymeric film that undergoes continual replenishment. In material engineering terms, polymer films that interact with the environment in seemingly intelligent ways are typically called “smart materials” (2,3). This designation seems particularly appropriate for the stratum corneum insofar as the epidermis is derived from the same embryonic germ tissue as the brain (both are ectodermal derivatives). The formation of the stratum corneum is the “raison d’être” of the epidermis (4). The stratum corneum, in this view, is the surface of the brain and manifests a close and obvious link to perception throughout life (5,6).
