liposomes is extremely small, double layer, hollow, spherical, phospholipid membrane vesicles able to encapsulate water-soluble as well as oil-soluble substances. Their compatibility and affinity with cellular membranes allow them to be easily accepted and metabolized by the skin, and provide the skin with “actives” that would not be so readily accepted otherwise. Liposome effectiveness is measured by their ability to deliver encapsulated actives ingredients to target sites. By varying the type of phospholipids used to make liposomes and/or by attaching certain molecules to the surface of liposomes, they can be engineered to have many useful properties, which include: releasing their active content upon reaching the target site; protecting ingredients from acidic and enzymatic degradation before reaching the target site; protecting compounds from premature oxidation; targeting certain tissues or cell types; acting as time releasers of valuable actives. In addition to their carrier abilities and penetration properties, liposomes provide the upper stratum corneum with a pleasant and smooth feeling. Liposomes are predominantly formed by phospholipids of natural, semisynthetic, and/or synthetic origin. Liposomes have brought to the cosmetic field widespread interest in the concepts of microencapsulation and targeted substance delivery.
