Transport systems for cosmetic ingredients: liposomes and other particles

Human skin quite reliably protects our body from the penetration of any substances from the outside. Only substances consisting of very small or very aggressive molecules can overcome this almost ideal barrier – if the molecule has a size greater than 500 Da, it will not be able to penetrate the skin on its own. Scientists have long tried to find a way to help substances with large molecules get into the deeper layers of the skin, and have created special systems for delivering ingredients. How liposomes and other delivery agents work was studied by estet-portal.com.

How do liposomes work as a system to deliver ingredients to the skin

There are not so many small molecules that are interesting from the point of view of cosmetology: for example, most peptides, retinol, niacinamide, and some hydroxy acids have an independent penetrating ability. For most substances that are of value to the health of the skin, its stratum corneum becomes an insurmountable barrier.

About 50 years ago, scientists discovered that phospholipids are able to fold into very peculiar spheres: in the process of twisting, the phospholipid captures part of the surrounding solution, along with the inorganic particles contained in it, and keeps it inside. In this case, the resulting sphere exchanges ions with the environment – like a cell membrane: it lets water in, but does not let trapped substances out. Such spheres were called liposomes and began to be used to deliver drugs to the body.

The discovery of liposomes has revolutionized pharmacology and cosmetology – after all, antibiotics, and vitamins, and chemotherapy drugs, and rejuvenating extracts could be placed inside the phospholipid sphere.

It was possible to make liposomes multi-layered: distribute different ingredients between the layers and force them to be released gradually – as the liposomes penetrate deeper into the skin. Today, tens of thousands of liposomal products and other transport particles with a similar effect have already been created, including those used in cosmetology.

Types of transport particles and features of their penetration into the skin

The transport particles used in cosmetology to deliver the right ingredients to the skin can be either variations of liposomes or other structures that have been adapted for some special ingredients.

• Nanoparticles. Spherical formations, microspheres, capable of capturing 5 times more useful ingredients than liposomes, but they can only carry fat-soluble substances. They easily penetrate the skin, but are very unstable – they are usually used to carry vitamins through the stratum corneum.
• Micro sponges. Synthetic polymers with a porous structure that can capture a lot of fat-soluble substances and then release them slowly, maintaining a constant concentration of these substances in the skin. They are used to deliver certain irritants to the skin – e.g. retinol, salicylic acid.
• Cyclodextrins. Starch-based, water-soluble cone-shaped particles that are able to retain fat-soluble ingredients inside and have a superficial effect on the skin – remove excess sebum. They are used in cosmetics for oily skin care.
• Solid lipid nanoparticles. Very small particles composed of lipids in aqueous solution. In addition to the ability to transfer active substances into the skin, they can act as a physical sunscreen, and therefore are included in sunscreen products – protect, moisturize and nourish the skin at the same time.
• Nanocrystals. Used to deliver poorly soluble biologically active ingredients (such as rutin) to the skin.
• Nyosomes. An aqueous cavity coated with a surfactant. These particles are more stable than liposomes, penetrate the skin faster and maintain the effect of the transferred drugs longer.

Thus, today cosmetics can affect not only the surface of the skin, but also penetrate into its deeper layers or affect some structures of the superficial or deep layers.