1. After completely thawing the fetal bovine serum, shake it gently, serum heat-inactivation is performed in a water bath at 56oC for 30 minutes. During the inactivation process, it is recommended to shake it regularly to balance the serum in the bottle with heat. It is also possible to use a small, sterile container to aliquot the serum before heat inactivation, but care must be taken to prevent contamination during the aliquot and heat inactivation process.

2. Heating inactivates the complement system, which activates complements that stimulate smooth muscle contraction, release histamine from cells and platelets, and activate lymphocytes and macrophages. According to their own research requirements, users can decide whether to heat inactivate the serum or not.

3. If not necessary, the heat treatment step may not be required. Experiments have shown that properly heat-inactivated serum is no needed for most cells. The treated serum only slightly promoted the growth of the cells, or had no effect at all. Usually, the high-temperature treatment affected the quality of the serum, which caused the cell growth rate decrease. Moreover, the formation of precipitates in the serum after heat treatment will increase significantly. Observation of these precipitates under an inverted microscope, like "small black spots", often makes researchers mistakenly believe that the serum is contaminated. Improper operation of heat inactivation process, such as excessive local temperature in the serum bottle, uneven shaking, too long inactivation time, temperature control instability and other factors, will cause the serum quality to decline. Heat treatment is not required unless necessary. Not only save time, but also ensure the quality of serum!