The skin is a complex organ with many layers. Its structure is designed to minimize moisture loss from the body while preventing foreign materials from entering. To accomplish these functions, the skin must have a protective covering of lipids, or oil-soluble molecules. Exposure to everyday conditions can strip the skin of its protective lipid covering. Therefore moisturizers containing some oil-soluble components are often used to restore the skin to its natural condition. Most moisturizers use a mixture of oil and water soluble components called an emulsion. More recently, researchers have begun incorporating liposomes, or small spheres of lipids, into moisturizers. Not only are these bubble-like structures useful for restoring the skin's protective lipid layer, but they can also carry active ingredients inside of them, increasing the potency of some cosmetic products.
Nothing hinders a smile like dry skin. Skin must maintain a certain amount of water inside to remain stretchy and feel comfortable. However, splashing water directly onto your face makes it feel drier than before. So how do moisturizers add water to your skin and keep it there? They require a combination of water and oil to work properly. A few different techniques for delivering moisturizers to your skin exist. Moisturizers often incorporate emulsion systems, which are mixtures of oil and water. They may also add a more recently developed technology that uses vesicles, or microscopic "bubbles" made out of biological components. In this article we will first describe emulsions, and then go into detail about a kind of vesicle called a liposome, which is commonly used in moisturizers. We will also explain why utilizing a vesicular system is generally superior to using emulsions only. First, however, a brief review of the skin's components is helpful.
The Skin
The skin is made up of three main layers: the epidermis, the dermis, and the hypodermis (Poucher 311).
As the deepest layer of skin, the hypodermis contains a layer of fat. It also houses blood vessels and nerves that are generally larger than those found in the dermis layer (Gray 10).
Within the dermis lie the blood vessels, nerves, and hair shafts, as well as sweat and sebaceous glands. The sebaceous glands produce an oily substance called sebum and secrete it into the hair shaft. Sebum migrates up to the top of the skin through the hair shaft, where it covers the outer layer of the epidermis, providing a protective barrier for the skin from the outside world. It consists of fatty acids, cholesterol, waxes, triglycerides, and a variety of other substances (Poucher 313). A small coating of sebum will protect the skin effectively. An excess of sebum leads to overly oily skin and can cause acne.
Within the epidermis are multiple sublayers. On the very surface of the epidermis lies a layer of fat (Poucher 311). Just beneath the fat is a layer of cornified cells, called the stratum corneum (Poucher 311). Beneath the cornified cells lies the horny layer, which consists of three sublayers (Poucher 312). At the bottom of the epidermis lies the basal layer, where cells are created. These cells then migrate up through the layers of the skin all the way to the stratum corneum, where they fall off the body (Poucher 312). This upward cell movement helps defend the skin from harmful invaders by acting like an ocean current, moving foreign debris up and out of the skin.
The skin is a complex organ with many layers. Its structure is designed to minimize moisture loss from the body while preventing foreign materials from entering. To accomplish these functions, the skin must have a protective covering of lipids, or oil-soluble molecules. Exposure to everyday conditions can strip the skin of its protective lipid covering. Therefore moisturizers containing some oil-soluble components are often used to restore the skin to its natural condition. Most moisturizers use a mixture of oil and water soluble components called an emulsion. More recently, researchers have begun incorporating liposomes, or small spheres of lipids, into moisturizers. Not only are these bubble-like structures useful for restoring the skin's protective lipid layer, but they can also carry active ingredients inside of them, increasing the potency of some cosmetic products.
