Sodium hyaluronate is the sodium salt form of hyaluronic acid, which is also called hyaluronic acid, abbreviated as HA, and is usually called hyaluronic acid.
According to the molecular weight, hyaluronic acid can be divided into four categories: high molecular weight hyaluronic acid, medium molecular weight hyaluronic acid, low molecular weight hyaluronic acid and oligomeric hyaluronic acid. It is recognized as the best moisturizing ingredient today and is widely used in cosmetics. How does sodium hyaluronate moisturize?
1. Understanding Sodium Hyaluronate
Commonly used in the cosmetics industry is sodium hyaluronate, which is the sodium salt of hyaluronic acid. There is no substantial difference in properties between hyaluronic acid and hyaluronic acid, and they are customarily referred to as hyaluronic acid.
From the perspective of chemical structure, hyaluronic acid is a high molecular weight polysaccharide compound formed by the polymerization of two monosaccharides, namely D-glucuronic acid (left half of the above picture) and N-acetylglucosamine (right half of the above picture). These two monosaccharides react to form a stable disaccharide, and then the disaccharide units are repeated to form hyaluronic acid.
2. How Does Sodium Hyaluronate Moisturize?
Since there are a large number of hydrophilic groups (especially hydroxyl-OH) on the surface of hyaluronic acid molecules, it can bind a large number of water molecules through hydrogen bonds, playing an excellent water absorption role, and the theoretical water retention value is 500ml/g. Hyaluronic acid is distributed in the dermis in large quantities, playing the role of a "water reservoir", preventing the skin from desquamation, tightness, dry lines and other phenomena due to reduced water content. Therefore, hyaluronic acid can prevent and improve wrinkles and delay aging.
Another significant feature of skin aging is relaxation, and hyaluronic acid also plays an important role in this regard. Its glycosidic bond is quite stable and firm, and it can form a viscous network tissue in an aqueous solution, giving the tissue good elasticity and pressure resistance. In the field of medical beauty, injection of hyaluronic acid can also fill and improve scars and depressions in the skin.
3. What Other Functions Does It Have Besides Moisturizing?
In addition to its well-known moisturizing, firming and filling functions, hyaluronic acid also plays a more important role as an extracellular matrix, regulating the interaction between cells. Hyaluronic acid is synthesized by cells such as fibroblasts, and then excreted outside the cells, which in turn affects the function of cells, such as promoting epithelial regeneration and wound healing, promoting phagocytic activity of granulocytes, regulating inflammatory responses, and resisting reactive oxygen free radicals.
In addition, hyaluronic acid can also be taken orally, based on the fact that digestion and absorption of hyaluronic acid can increase the synthesis of hyaluronic acid in the skin and other tissues. Theoretically, topical hyaluronic acid cosmetics only act on the surface of the skin where they are applied, while oral hyaluronic acid has a systemic effect and can overcome the disadvantage that hyaluronic acid is not easily absorbed by the skin.
It is generally believed that hyaluronic acid has a large molecular weight and cannot penetrate normal skin. So researchers racked their brains to improve it and developed small molecule hyaluronic acid or cross-linked hyaluronic acid. The so-called small molecule hyaluronic acid refers to a molecule in which the number of repeated disaccharide units does not exceed 1000 and the molecular weight is less than 1×106. Hyaluronic acid can also be degraded by enzymes and then specially processed to form oligomeric hyaluronic acid. Its molecular weight is smaller and can even be absorbed through the skin, exerting effects that conventional hyaluronic acid cannot achieve.
In addition, the cross-linking reaction of hyaluronic acid macromolecules can be achieved by chemical means, turning two-dimensional linear molecules into three-dimensional spatial network structures. The cross-linked hyaluronic acid polymer obtained in this way can last longer in the body while retaining its original advantages. It has important applications in the fields of cosmetic plastic surgery fillers, bone and joint injections, anti-adhesion products, hemostatic products, etc.
4. Conclusion
Hyaluronic acid is a natural ingredient widely found in human connective tissue. It is very safe as a cosmetic raw material for external use and a special food raw material for oral use. The concentration for external use is generally 0.05%-0.15%. However, there may be contraindications and adverse reactions in injection filling, and it is contraindicated for those who are allergic to hyaluronic acid.