Section 1 Concept and Function of Hyaluronic Acid
1. What is hyaluronic acid?
Hyaluronic acid is the source of life. The aging body will gradually lose water. The most important substance for human tissues to retain moisture is hyaluronic acid. 1. Hyaluronic acid is a kind of hyaluronic acid, also known as hyaluronic acid, or HA for short; it is widely present in the dermis of the skin. 2. Its appearance is a transparent, sticky gel-like substance, which is a high-molecular polysaccharide. 3. Hyaluronic acid is recognized as the best moisturizing product in current literature and is called the best “moisturizing factor”; 1g of hyaluronic acid can lock in water equivalent to 500 times its own weight, so hyaluronic acid is also called the “skin absorbent sponge”
2. The role of hyaluronic acid

1. Water-locking hyaluronic acid captures moisture in the air and forms a hydration-like protective film on the skin surface. This film can isolate external bacteria and dust and lock in moisture.
2. Water storage: Since hyaluronic acid can absorb 500 times more water than itself, it will expand itself after entering the dermis layer to absorb water, increasing the skin’s water capacity and storing more water. 3. Filling and shaping hyaluronic acid exists in the elastic network constructed by elastic fibers and collagen fibers in the dermis. Enough hyaluronic acid can solidify the elastic network and increase skin elasticity.
Section 2 Common Sources of Hyaluronic Acid Three Common Sources of Hyaluronic Acid
1. How are animal sources prepared? The main raw materials are cockscomb and bull’s eye vitreous body. Degrease and dehydrate the raw materials with acetone or ethanol, soak in steamed water, filter, then treat with sodium chloride aqueous solution and chloroform solution, then add trypsin and keep it warm to obtain a mixed solution, and finally use an ion exchanger to process and purify to obtain a refined product. of hyaluronic acid. The extraction rate of this method is low, only about 1%, and the separation process is complicated.
2. What is the preparation method of chemical synthesis? Using natural enzyme polymerization, first use polysaccharide polymers to synthesize “hyaluronic acid oxazalene derivatives”, then hydrolyze enzymes to create a complex of derivatives and enzymes, and finally in the reaction solution at 90 degrees Celsius By removing the enzymes, hyaluronic acid is synthesized. Artificial synthesis can greatly reduce the manufacturing cost of hyaluronic acid, but the structure is not pure.
3. What is the preparation method of microbial fermentation? Use glucose as the carbon source in the fermentation broth. Ferment in the culture medium for 48 hours. After the fermentation is completed, filter to remove mycelium and impurities, and then use simple operations such as alcohol precipitation to obtain a high-purity product. The fermentation method is used to produce hyaluronic acid. The advantage is that the molecular weight can be set according to the needs. size. The key to the fermentation method lies in the selection of bacterial strains. Currently, Streptococcus, Lactococcus, etc. are mostly used.
Section 3 Hyaluronic acid cross-linking
1. Why does hyaluronic acid need to be cross-linked? Non-cross-linked hyaluronic acid can only maintain its effect in the human body for a few days or even hours. Cross-linking agents are used to connect linear non-cross-linked hyaluronic acid together to make hyaluronic acid products with higher viscoelasticity. A single use of cross-linking technology Or products that have been treated multiple times can maintain their effects for 3-9 months due to differences in molecular size or quantity. The main uses are filling and shaping.
2. What are the uses of non-cross-linked hyaluronic acid?
1. Mainly used for joint injections (drug-sodium hyaluronate injection).
2. Ophthalmic surgery and medical equipment – auxiliary materials for eye surgery, including cataract surgery (intraocular lens transplantation), keratoplasty, glaucoma surgery, etc.
3. High-end cosmetics (mainly for hydration).
4. Eye drops (drugs to relieve dry eyes).
5. Beauty and health foods (oral health products).
3. Cross-linking and modification:
The “modified” means that sodium hyaluronate has been chemically cross-linked. “Cross-linked” can also be used, but “modified” means that the degree of cross-linking is lighter.
4. What is the function of cross-linking agent? It is a substance that can play a bridging role between linear molecules, thereby bonding and cross-linking multiple linear molecules to each other to form a network structure. Substances that promote or regulate the formation of covalent or ionic bonds between polymer molecular chains.
5. Cross-linking degree: The cross-linking degree is also called the cross-linking index, which indicates the degree of cross-linking of the polymer chain. The cross-linking degree can be measured by mechanical means or the equilibrium swelling ratio method.
6. Relationship between cross-linking agent and cross-linking degree
Uncross-linked hyaluronic acid is composed of long polysaccharide molecules. There is no “contact” between the molecular chains, and they are dispersed and “do not interfere with each other.” Hyaluronic acid in this state is mostly liquid. If such hyaluronic acid is injected When it enters the skin, it will not only fail to achieve the shaping effect because it has no three-dimensional shape, but it will also be easily degraded by hyaluronidase in the skin and will be quickly absorbed by the skin. Therefore, in the production process of hyaluronic acid cosmetic injections, cross-linking agents (currently commonly used are BDDE and DVS) are artificially added to connect the hyaluronic acid molecular chains into a network, so that the structure is relatively stable, not easy to “fall apart”, and lasts for a long time after injection. After cross-linking hyaluronic acid, it depends on the degree of cross-linking. The higher the degree of cross-linking, the stronger the anti-degradation ability of hyaluronic acid, and the effect of hyaluronic acid injection can last longer. The higher the degree of cross-linking, the better. Everything is different. There is a certain degree. The ideal hyaluronic acid should be highly cross-linked. After the hyaluronic acid is absorbed, the remaining cross-linking agent will be basically metabolized.
Section 4 Uses of large, medium and small molecule hyaluronic acid
Hyaluronic acid with different molecular weights targets different parts during treatment.
1. Small molecule hyaluronic acid is mainly used to correct fine lines. The injection level is shallow and the effect lasts short.
2. The molecular weight of medium-molecule hyaluronic acid is closest to the molecular weight of human cells, so it is more suitable for soft tissue filling, such as tear trough, temple, and forehead treatment, and the effect lasts longer.
3. Macromolecule hyaluronic acid metabolizes slowly, retains for a long time, and has a harder texture, so it is suitable for facial shaping treatments, such as rhinoplasty, chin augmentation, etc., and its effects last the longest.
Section 5 Hyaluronic acid and skin problems
1. Sensitivity is caused by the imperfect sebum membrane of the skin. Hyaluronic acid can help repair damaged sebum membranes and solve skin allergies.
2. Dryness, dullness, dullness, and spots are caused by the lack of moisture in the skin, slowed cell metabolism, inability to remove garbage in time, and insufficient nutrient supply. Hyaluronic acid can help the skin store and lock a large amount of moisture, metabolize waste in the skin, and solve various skin problems caused by poor skin metabolism.
3. Loose wrinkles The loss of hyaluronic acid will cause the collagen fibers and elastic fibers to collapse and relax. The skin appears wrinkled and sagging. Hyaluronic acid enters the dermis to strengthen the fibrous layer and resolve loose wrinkles and other phenomena.
Section 6 The relationship between hyaluronic acid and collagen
Collagen and elastin form a network structure. This network structure is equivalent to the steel bar of the skin, which plays a supporting role and is related to skin elasticity, true wrinkles, sagging and other problems. Hyaluronic acid is the filling material between color cells and collagen fibers. The gel-like object is equivalent to cement, which can moisturize, stabilize and resist collapse, so hyaluronic acid and collagen are more effective when used together.
Section 7: Supplementing hyaluronic acid
Reason 1: Hyaluronic acid exists in the dermis of the skin. The hyaluronic acid content of baby’s skin is as high as 100%, so the skin is smooth, delicate and elastic.
2. Hyaluronic acid begins to disappear at the age of 25. At the age of 30, only 65% ​​of young skin is left, and at the age of 60, only 25% of young skin is left.
3. Insufficient hyaluronic acid will reduce the skin’s ability to store and lock water, causing various skin problems. Section 8 Reasons for the speed of hyaluronic acid absorption
1. Different individuals have different physiques, and the metabolism rate of hyaluronic acid is also different. 1. People with thin body types absorb and metabolize hyaluronic acid faster than those with fat body types. 2. In addition, when people of different ages inject the same dose of hyaluronic acid into the same site, the metabolism time is also different. The reason is that older people have less hyaluronic acid content in their skin, and the absorption rate after injection is faster than that of young people. , the maintenance time will also be shorter. 3. The skin lacks moisture for a long time and hyaluronic acid is absorbed quickly.
2. The first injection of hyaluronic acid will be absorbed quickly. When skin cells lack moisture, hyaluronic acid is absorbed quickly. When the skin has sufficient moisture, hyaluronic acid is absorbed slowly. When hyaluronic acid is not completely absorbed, it is recommended to reapply hyaluronic acid, which can increase the maintenance time of hyaluronic acid. Several consecutive refills of hyaluronic acid will relatively extend the maintenance time.
3. If personal habits are not good, hyaluronic acid will also accelerate absorption. Bad habits have an impact on the absorption of hyaluronic acid. Frequent drinking, staying up late, etc. will also accelerate the absorption of hyaluronic acid. Drinking alcohol will accelerate blood circulation and cause hyaluronic acid to be lost faster. Staying up late will cause the skin to be dehydrated, and the skin will also absorb a large amount of hyaluronic acid. If the skin is dry and dehydrated, the absorption of hyaluronic acid will be accelerated.
4. Different hyaluronic acid products have different effects and maintenance time. Different brands of hyaluronic acid will affect the time of hyaluronic acid in the human body due to factors such as molecular weight, cross-linked sodium hyaluronate content, and ingredients.
5. Different injection sites affect the absorption speed of hyaluronic acid. The injection site and corresponding facial expression activity also affect the maintenance time of hyaluronic acid. Since the nose and chin have no active muscles, the expression activity is low and the maintenance time is relatively long. The nasolabial folds, apple muscles and lips are areas with high facial expression activity, and the maintenance time of hyaluronic acid is relatively short.
6. Personal psychological effects and misunderstanding of the absorption and metabolism of hyaluronic acid. After injecting hyaluronic acid, the skin will be slightly hard due to swelling, and you may feel satisfied with the shaping effect. As time goes by, the swelling subsides, and the hyaluronic acid injected into the skin merges with the skin, becoming soft and like its own body. Customers mistakenly believe that hyaluronic acid is absorbed quickly.

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