Liposomes are spherical vesicular structures that are physiologically present in the spinous layer of the epiderma. The physiological liposomes form in the Golgi bodies and are transported from the basal layer to the outer layers of the epidermis to contribute to the lipid component of the skin barrier.
What they are and what they are for
Liposomes are known as “membrane-mimetic” systems because they have structure similar to membrane lipids, which were already used in the pharmaceutical field as carriers for the transport of substances with pharmacological activity and as a synthetic model of bio-membranes before the cosmetics world turned its interest to this delivery system (the first liposome-based cosmetic was produced in 1987), with an ever-increasing trend.
Technically, liposomes are lipid phospholipids organized in single- or double-layered vesicles containing a central aqueous cavity; These small structures are formed by the presence of constituents with hydrophobic tail akin to lipids and a hydrophilic head akin to water and hydrophilic substances, in a manner completely similar to cellular membranes.
Use in cosmetics: advantages and disadvantages of liposomes-based products
What advantages do liposomes-based cosmetics offer? First of all, their high biocompatibility, due precisely to their membrane-lipid-like structure, which makes them practically hypoallergenic. Moreover, they offer a range of formulative advantages: from the elimination of organic solvents, based on their ability to incorporate hydrophilic and lipophilic substances, to the protection of functional ingredients from the physiological action of the enzymes that cosmetics ‘encounter’ during application on the skin, as well as the ability to intervene on the skin hydration by enhancing the skin’s natural barrier function. Any functional degradation due to the pH of the skin can also be “bypassed” with this application technology.
The small size of the liposomes and their membrane-like nature allows them to pass through the stratum corneum with the possibility of acting as moisturizers in their own proper form and also preserving unstable actives from enzymatic degradation. Depending on size, a distinction is made between mono-, unilamellar and plurilamellar liposomes, while phytosomes are referred to when soya phospholipids are used to carry plant active ingredients, such as glycyrrhetinic acid (derived from liquorice) which has problems of solubility in a classical formulation.
The disadvantages of liposomes are mainly technical: given the complex nature of the liposome structures, the production and sales costs of raw materials are high; furthermore
the possible presence of emulsifiers or surfactants in the formulation may lead to alteration in the liposome structure due to the possibility of interactions with amphiphilic structures.
From the point of view of application in the cosmetics industry, starting with face and body creams pioneered for the use of liposomes, it is now also possible to find them in aftershaves, toothpastes, lip softeners and many other cosmetics.
We should point out that sometimes consumers mistakenly think that the indication “liposome” is found in the list of ingredients: but these are carrier systems, so they will be indicated in the product description. The technical and detailed description of the liposomal system can also prove to be a marketing weapon, if correctly used, to explain the scientific nature of a cosmetic preparation to the end consumer.