Some humectants are highly hygroscopic and attract water from the air and tissues surrounding the skin. These only work well when there is sufficient humidity in the air to draw from. Phospholipids are natural humectants contained in cells and actually form an evaporative and protective barrier in the outer layer of the epidermis. Because these cells are keratinized and no longer living, the repairative mechanisms are inactive. Loss of phospholipids due to detergents, solvents, or environmental factors can weaken the epidermal barrier and cause the skin to look and feel rough.
Liposomes are a relatively new development in skincare formulations.
Liposomes can carry vitamins , drugs, or other active ingredients internally for delivery to the dermis. Because of their cell membrane -like structure they can readily pass through the epidermis and are thought to be accepted into cells of the dermis by membrane fusion.