Serum refers to a light yellow transparent liquid separated from fibrin in plasma or a plasma in which fibrin has been removed after blood coagulation. Its main role is to provide basic nutrients, provide hormones and various growth factors, provide binding proteins, provide pro-contact and stretching factors to protect cells from mechanical damage, and provide some protection to cells in culture.
Serum category:
Fetal bovine serum, dialyzed fetal bovine serum, natural low IGG fetal bovine serum, stem cell cultured fetal bovine serum, special purpose fetal bovine serum, activated carbon/glucose treated fetal bovine serum, fetal bovine serum replacement, calf serum, newborn bovine serum , enhanced calf serum, iron supplemented calf serum, bovine serum, donor horse serum, rabbit serum, chicken serum, pig serum, horse serum, other animal serum, synthetic serum substitute
Main ingredients:
Serum is a complex mixture of plasma-depleted fibrinogen. Although most of its components are known, some of them are still unclear, and serum composition and content often follow the sex, age, and physiology of blood-feeding animals. Conditions and nutritional conditions vary. The serum contains various plasma proteins, peptides, fats, carbohydrates, growth factors, hormones, inorganic substances, etc., which are physiologically balanced for promoting cell growth or inhibiting growth activity. Although there has been great progress in the study of the composition and action of serum, there are still some problems. mainly:
First: there may be hundreds of serum components. At present, the exact composition, content and mechanism of action are still unclear, especially for some of the peptide growth factors, hormones and lipids. Bringing many difficulties to research work;
Second: the serum is produced in batches, the difference between the batches is very large, and the serum preservation period is up to one year. Therefore, it is extremely difficult to ensure the similarity of each batch of serum, so that the standardization and continuity of the experiment are limited;
Third: It cannot be ruled out that serum contains volatile substances, which is considered to be one of the causes of "deterioration in the bottle".
Identification method:
A light yellow transparent liquid that is coagulated by blood. If the blood is taken out from the blood vessel and placed in a test tube without an anticoagulant, the blood coagulation reaction is activated, and the blood rapidly solidifies to form a jelly. The clot is contracted, and the pale yellow transparent liquid deposited around it is serum, and can also be obtained by centrifugation after coagulation. During the blood coagulation process, fibrinogen is converted into fibrin blocks, so there is no fibrinogen in the serum, which is the biggest difference from plasma. In the blood coagulation reaction, platelets release many substances, and each clotting factor also changes. These components remain in the serum and continue to change, such as prothrombin to thrombin, and gradually decrease or disappear with serum storage time. These are also differences from plasma. However, a large number of substances that did not participate in the blood coagulation reaction were basically the same as plasma. In order to avoid the interference of anticoagulants, the analysis of many chemical components in the blood uses serum as a sample. [3]
plasma
Blood component
Plasma is a liquid component of blood in which blood cells hang. The human body contains 2750-3300 ml of plasma, which accounts for about 55% of the total blood volume. The vast majority of plasma is water (90% by volume), in which the dissolved substances are mainly plasma proteins, including glucose, inorganic salt ions, hormones, and carbon dioxide. The main function of plasma is to carry blood cells, and it is also the main medium for transporting secreted products.
The fresh blood is centrifuged to sediment the blood cells, and the upper layer of pale yellow serum is plasma. The difference between plasma and serum is that serum does not contain blood clotting factors such as fibrinogen. [4]
main role
â— Provide basic nutrients: amino acids, vitamins, inorganic substances, lipids, nucleic acid derivatives, etc., which are essential for cell growth.
â— Provide hormones and various growth factors: insulin, adrenocortical hormone (hydrocortisone, dexamethasone), steroid hormones (estradiol, testosterone, progesterone). Growth factors such as fibroblast growth factor, epidermal growth factor, platelet growth factor and the like.
• Providing a binding protein: The binding protein acts to carry important low molecular weight substances, such as albumin carrying vitamins, fats, and hormones, and transferrin carries iron. Binding proteins play an important role in cellular metabolism.
• Provides pro-contact and stretching factors to protect cells from mechanical damage.
â— Some protection for cells in culture: Some cells, such as endothelial cells and bone marrow-like cells, can release proteases, and the serum contains anti-protease components to neutralize. This effect was discovered by chance, and now there is a purpose to use serum to stop the digestion of trypsin. Because trypsin has been widely used for digestion and passage of adherent cells. Serum proteins form a serum viscosity that protects cells from mechanical damage, especially when suspended in suspension. Serum also contains trace elements and ions, which play an important role in metabolic detoxification, such as SeO3, selenium, etc. [2]
common problem
The best way to preserve serum?
Serum should be stored at -5C to -2OC. However, if stored at 4C, do not exceed one month. If you are unable to use one bottle at a time, it is recommended that the serum be aseptically filled into a suitable sterile container and returned to the freezer. [5]
How to thaw serum will not damage the quality of the product?
After the serum was taken out of the freezer, it was first placed in a 2-8C refrigerator to dissolve it, and then completely dissolved at room temperature. However, it must be noted that the dissolution process must be uniformly shaken regularly. [5]
How to avoid the formation of sediment?
1. When thawing serum, please follow the recommended step-by-step thawing method (-2O.C to 4. C to room temperature). If the temperature is too large when the serum is thawed (such as -20 ° C to 37 ° C), the experiment shows It is very easy to produce sediment.
2. When thawing serum, please shake it evenly at any time to make the temperature and composition uniform, and reduce the occurrence of sedimentation.
3. Do not put serum in 37. C is too long. If at 37. When C is placed for too long, the serum becomes cloudy, and many of the more unstable components in the serum are also damaged, which affects the quality of the serum.
4, the heat inactivation of serum is very likely to cause an increase in sediment, if not necessary, you do not need to do this step.
5. If you must do the heat inactivation of serum, please observe 56. C, 30 minutes principle, and shake evenly at any time. If the temperature is too high, the time is too long or the shaking is uneven, it will cause an increase in sediment. [5] After the serum is thawed, flocculent precipitates are found. How to deal with them? To remove these flocculent sediments, the serum can be dispensed into a sterile centrifuge tube, centrifuged slightly at 400g, and the supernatant can be added to the culture. The base is filtered together. However, it is not recommended to remove these flocculent deposits by filtration as it may clog the filter membrane. [5]
What is heat inactivation?
The thawed serum is usually treated at 56 C for 30 minutes, because this heating step can deactivate complement, and the reactions involved in complement are: cytolytic activity, contraction of smooth muscle, release of histamine from mast cells and platelets, Enhances phagocytosis, chemotaxis and activation of lymphocytes and macrophages. [5]
Is it necessary to do heat inactivation?
Experiments have shown that properly treated heat-inactivated serum is not required for most cells. The serum thus treated has only a slight promotion to the growth of the cells, or has no effect at all, and even the high temperature treatment usually affects the quality of the serum, resulting in a decrease in the cell growth rate. In the heat-treated serum, the formation of precipitates is significantly increased. These precipitates are observed under an inverted microscope, such as "small black spots", which often cause the researchers to mistake the serum for contamination, and put the serum at 37C. In the environment, this precipitate will be increased, which makes the researchers mistakenly believe that it is the splitting and amplification of microorganisms.
Therefore we recommend that you do not need to do the heat treatment if it is not necessary. In this way, not only save your precious time, but also ensure the quality of your serum! In addition, the purchase of inactivated finished products is also a shortcut, please pay attention to ask if the manufacturer is inactivated serum.
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