It is recommended that serum should be stored at -10°C or below. If one bottle cannot be used at a time, aseptically dispense the serum into appropriate sterilized containers and return it to the freezer. When thawing, it is recommended to move the serum from the freezer to a refrigerator at 2-8°C to thaw, and then place it at room temperature for complete thawing. Note that frequent shaking is required during thawing to mix. It is strictly forbidden to incubate and thaw FBS at 37°C for a long time.

All ExCell Bio serums are shipped frozen on dry ice, so they should still be frozen when you receive them. If it is only partially thawed, FBS can still be used, but it is recommended to fully thaw FBS in the refrigerator first, then shake it gently, and then move it to -10°C or below for storage.

Please confirm whether the cell culture protocol requires heat inactivation of serum. Heat inactivation is generally not recommended, as heat inactivation will lose part of the nutrients in the serum, and protein aggregation and precipitation will easily occur; a few experiments that are sensitive to complement are required (such as some immunological experiments, adenovirus packaging, some PS cultures, etc. ), heat-inactivated serum may be used as appropriate. Heat inactivation method: The serum is completely thawed and shaken well, then placed in a 56°C water bath for 30 minutes, and shaken evenly from time to time during the period.

Serum contains a small amount of hemoglobin, which is related to the number of broken blood cells during blood collection. As long as the hemoglobin content is within the range specified by the Pharmacopoeia, the color depth has nothing to do with the quality of the serum and will not affect cell culture. The Chinese Pharmacopoeia stipulates that the hemoglobin content is ≤200mg/L.

Once you find that black spots are formed during the cell culture process, first of all, you should observe with the naked eye whether the medium is turbid, and then observe the growth status of the cultured cells under a microscope, and whether the black spots are swimming. If the cells are contaminated, the microorganisms will proliferate, and the medium will quickly turn yellow and become turbid. Pollution includes bacterial pollution, mycoplasma pollution, etc. If the cells are in good growth state under the microscope, and there is no change compared with before the appearance of black spots, then the appearance of black spots may be related to the following situations: ①The cells grow too old, broken cell debris; ②The pH value of the prepared medium is too high, which is not suitable for cell growth; ③Small black spots appear in the cultured primary cells, which may be impurities in the primary tissue, which can be eliminated by multiple passages; ④The serum level is not enough to maintain the good growth of cells.

Not necessarily, the quality of the serum is not necessarily related to the place of origin. In addition, there is no best serum, only the most suitable serum.

The flocs in FBS may be caused by many reasons. The most common precipitates are mainly fibrin and lipoprotein, which will not affect the quality of serum. If the precipitate needs to be removed, depending on the size of the precipitate, centrifuge at 500-1000×g 5-10min to remove, or not to deal with.

Once you have added serum and antibiotics to your fresh medium, you should use it within 2 weeks.