Serum preservation points and basic techniques

(1) Serum that needs to be stored for a long time must be stored in a low temperature refrigerator at -20 ° C - 70 ° C. The storage time in the refrigerator at 4 ° C must not exceed 1 month. The volume will increase by about 10% due to serum icing, therefore, the serum is Before freezing into a low-temperature refrigerator, a certain volume of space must be reserved, otherwise it is prone to pollution or glass bottle cracking.
(2) The serum provided by the general manufacturer is sterile and does not need to be filtered and sterilized. If serum is found to be suspended, the serum can be added to the culture solution and filtered together. Do not directly filter the serum.
(3) The thawing of bottled serum should be carried out by gradual thawing method: -20 ° C to -70 ° C. The serum in the low temperature refrigerator is dissolved in a refrigerator at 4 ° C for 1 day. Then it is transferred to room temperature, and then completely dissolved before being dispensed. During the dissolution process Keep shaking gently (be careful not to cause bubbles), make the temperature and composition uniform, reduce the occurrence of sedimentation. Do not directly thaw the serum from -20 ° C into 37 ° C, so that the temperature changes too much, it is easy to cause protein agglutination Precipitation occurred.
(4) Heat inactivation refers to the freezing of serum that has been completely thawed at 56 ° C for 30 minutes. It should be shaken regularly during heating. The purpose of this heat treatment is to inactivate the complement in the serum. Unless necessary, generally not This heat treatment is recommended because heat treatment will cause a significant increase in serum sediments, and will also affect the quality of serum. Complement is involved in the reaction: cytotoxicity, smooth muscle cell contraction, mastamine and platelet release of histamine, enhance phagocytosis, promote lymphatics Cells and macrophages undergo chemotactic and activation.

(5) Do not leave the serum at 37 °C for too long, otherwise the serum will become turbid, and the active ingredients in the serum will break and affect the serum quality.

(6) Precipitate floc in serum: mainly caused by denaturation of lipoprotein in serum and fibrin in serum after thawing. These flocs do not affect the quality of serum itself. It can be removed by centrifugation at 3000 rpm for 5 minutes. Can be used without treatment. Microscopic "small black spots": After heat-treated serum, the formation of precipitates will increase significantly. Some sediments are observed under the microscope like "small black spots", often mistaken for serum contamination. Under normal circumstances This small black spot does not affect cell growth, but if serum quality is suspected, stop using it immediately and replace another batch of serum.

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