It is in the dermis that important regenerating processes take place that contribute to the youthfulness of the skin. And it is there that the presence of many biologically active substances that can trigger the mechanisms of recovery and rejuvenation is required. How to deliver biologically active substances to the deep layers of the skin? Scientists have invented transdermal systems for delivering active substances to the deep layers of the skin – liposomes. But let’s find out how effective liposomes are in a cosmetic composition?
What are liposomes?
Liposomes are artificially created microscopic vesicles (vesicles) with liquid content, which consist of one or more phospholipid bilayers separated by an aqueous phase. The word liposomes comes from the Greek lipos meaning fat and soma meaning body. Fat droplets in water are very similar to liposomes.
The similarity, of course, is purely external, but in this way one can imagine what liposomes are. Liposomes come in different sizes, and their shape often depends on their environment: acidity, the presence of salts, etc. Liposomes have been known for a long time, but for the first time British scientists paid attention to them.
It was they who noticed the fact that liposomes in their structure resemble cell membranes. Even then, scientists knew about the important functions that cell membranes performed, and liposomes became an important link for their research. Liposomes began to be used as models of cell membranes to study the effects of certain active substances on them. It is this fact that attracted the attention of scientists, as it became known that liposomes are good transport agents.
Methods of using liposomes in cosmetology
Liposomes have unique properties, due to which they began to be used as a transdermal system:
- liposomes simultaneously deliver various biologically active substances;
- liposomes are easily integrated into lipid bilayers of membranes and literally merge with skin cells;
- the structure of liposomes is similar to the structure of cell membranes.
All these factors contribute to the delivery of substances inside the liposome to the destination and control their release.
At first, liposomes were used as models of biological membranes. Then their functions were expanded and began to be used as microcontainers that are capable of delivering therapeutic ingredients to various organs and tissues. Liposomes can contain hormones, amino acids, trace elements, enzymes, vitamins, and even antibiotics. Today, two methods of delivering active substances in liposomes are known:
- transepidermal method;
- transfollicular method.
The transepidermal path consists in passing through the outer layers of the skin, and the transfollicular path consists in passing through the ducts of the sweat glands and hair follicles. There are also very unusual ways of using liposomes: in the form of powders.
Bath foams and body cosmetics are made in this way. Upon contact of the powder with water, liposomes are instantly formed, which cover a large perimeter of the skin. Liposomes formed in this way are especially beneficial for dehydrated and sensitive skin. Also, many other uses of liposomes have been patented in the cosmetics industry.
What are liposomes
Depending on the size and number of lipid layers, the following liposomes are distinguished:
- small monolamellar, with a single lipid bilayer;
- large monolamellar, also with a single bilayer;
- multilayered (multylamellar), with several tens and even hundreds of lipid bilayers.
The shape of liposomes depends on the process of their production. Over time, they are able to change the number of layers, shape and size, that is, they can be unstable. Interesting metamorphoses occur with them: small vesicles (vesicles) are able to form large ones, and large ones can turn into small ones.
However, all the above metamorphoses do not affect the quality of liposomes in any way, their properties remain unchanged. Liposomes penetrating the skin change their properties: they deform, disintegrate into fragments, in other words, change their original appearance. Researchers were interested not only in the transport abilities of liposomes, but also in their ability to act as self-contained cosmetics.
How are liposomes obtained?
The invention of liposomes relates to applied biotechnology and even nanotechnology. Since liposomes have sizes corresponding to nano-sizes for passing through the protective layer of the epidermis.
Liposomes are obtained by mixing biologically active substances and additional substances (solvents, powder fillers and phospholipids) in a certain container or by sonicating aqueous phospholipid systems. This method greatly simplifies and reduces the cost of the production of liposome preparations and significantly improves the process of encapsulation of biologically active substances in liposomes.
Also, liposomes can be formed from characteristic phospholipids, natural or synthetic, as well as from a mixture of phospholipids.
The action of liposomes on the skin – are the hopes justified?
By themselves, liposomes are completely useless. Their ability to play the role of transport agents is quoted. That is, inside the liposomes there is an empty space that can be filled with unstable compounds. The structure of liposomes allows you to protect unstable compounds of active substances from the destructive effects of the environment. They seem to envelop the substance with a strong membrane.
High hopes were placed on liposomes. They were supposed to be effective transporters of rapidly degrading active substances. In addition, we learned above that liposomes are easily integrated into the cell structure and completely dissolve in it. Because the structure of the liposome shell and the structure of the cell membrane have a similar structure.
It is known that many active substances included in the cosmetic composition remain on the surface of the epidermis. For example, vitamins without enhancers (conductors) are destroyed immediately by oxygen and sunlight even before they are applied to the skin.
In order to bring vitamin A into the skin, its encapsulated form is used, which is added to the cream. Vitamin A is a very unstable compound and tends to break down already in the cream, and in a special capsule it retains its regenerating qualities. Or a cream containing coenzyme Q10 immediately becomes useless and meaningless, since the enzymes do not pass beyond the stratum corneum, but remain on its surface.
The aspirations of scientists are becoming quite understandable. For decades, the search has been carried out for a universal transporter capable of ideally transporting active substances deep into the skin. But, unfortunately, it has not yet been found. After all, some…