Phospholipids when hydrated form spherical vesicles having one or more lipid bilayers (unilamellar or multilamellar LIPOSOMES). This is a result of the unique property of phospholipids to self assemble in an aqueous medium. The hydrophilic heads form the outermost and innermost layers to protect the lipophilic tails. Modified phospholipids may also be used to form unimeric conical nanoparticles (MICELLES).
Skin is the largest organ and it is protected by a fragile hydrolipid film that functions as a protective barrier from the external world. The epidermis is the outer layer of the two layers that make up the skin, the inner layer being the dermis. The epidermis is further composed of 4 or 5 sub-layers. The cells in each of these layers are surrounded in the extracellular space by stacked layers of lipids. The fatty acid composition of Phospholipids mimics that of the lipids of the hydrolipid film as well as the epidermal lipids. Because of this structural similarity, Phospholipids are often called as “second skin”.
Healthy hair is maintained through regeneration of hair follicles by activation of multipotent epithelial stem cells residing in the outer hair root sheath. The hair cycle is comprised of a finite period of hair growth (anagen phase), a brief regression phase (catagen phase), and a resting period (telogen phase). It is regulated by sensory neurons, cytokines, growth factors (GFs), and hormones. The growth of new hair requires re-entry into the anagen phase. Phospholipids possess potent growth effects on murine hair epithelial cells, thereby inducing early telogen-to-anagen phase conversion, promoting cell growth, and elongating shafts in hair follicles. Phospholipids also combine with the proteins (keratin) of the hair and simultaneously fixate the fat-soluble hair care substances carried along leaving hair supple and conditioned.