How should serum be stored?
Serum can be stored at normal temperatures or at -20°C or -80°C. For long-term storage, it is recommended to store serum at -80°C. Unopened serum should also be stored at -80°C. Serum that has been thawed at 2-8°C should be used as soon as possible.
How should serum be thawed?
Serum should be thawed slowly and gently at 2-8°C to prevent protein denaturation and loss of activity. It is not recommended to use a microwave or hot water bath for thawing.
What is the shelf life of serum?
Serum stored at -80°C can typically last for 5 years (if not repeatedly thawed and refrozen).
Can expired serum still be used?
Expired serum should not be used as it may have reduced activity or contain contaminants that could affect experimental results.
How many freeze-thaw cycles can serum withstand?
Repeated freeze-thaw cycles can cause protein degradation and loss of activity in serum. It is recommended to avoid more than 2-3 freeze-thaw cycles.
Is it necessary to inactivate serum?
In most cases, serum does not need to be inactivated. Inactivation can lead to the destruction of certain components in serum, such as amino acids, vitamins, and growth factors. Only in cases where serum has specific requirements for an experiment would inactivation be considered.
Why does serum stored in a refrigerator form a precipitate?
When stored at 2-8°C, various proteins or lipoproteins in the serum can form visible precipitates, such as fibrinogen. When fibrinogen is in a monomeric state, it is in a dissolved state, but during the freeze-thaw process, it can aggregate and form visible precipitates. However, this phenomenon generally does not affect the performance of serum.
How can the formation of serum precipitates be avoided?
Centrifuging the serum at 400g for 5 minutes and then filtering the supernatant can help avoid the formation of serum precipitates. Choosing an appropriate filter membrane pore size, such as a 0.22um PES filter membrane, is recommended to avoid filter blockages. To minimize the risk of serum precipitation, it is suggested to aliquot serum into single-use portions and store them at -15°C to -20°C, and avoid repeated freezing and thawing or leaving thawed serum at 2-8°C for extended periods of time.
Should serum be depleted of abundant proteins before analysis?
Depletion of abundant proteins can improve the detection of low-abundance proteins and metabolites. However, the choice of depletion method should be carefully considered as it may affect the detection of certain proteins and metabolites.
Can different serum collection tubes affect experimental results?
Yes, different serum collection tubes can affect experimental results. It is important to use consistent collection tubes to minimize variability between samples.
Can serum be contaminated by hemolysis during collection?
Yes, hemolysis during collection can contaminate serum with red blood cell components, which can interfere with experimental results.
How can hemolysis be detected in serum samples?
Hemolysis can be detected by visual inspection of the serum or by measuring the absorbance of hemoglobin at 414 nm. Samples with hemolysis should be discarded or processed separately.
Can serum from different species be used for metabolic and proteomic analyses?
Serum from different species can be used for metabolic and proteomic analyses, but it may require additional steps to remove cross-reacting proteins or to identify species-specific proteins.
Can serum be used as a surrogate for tissue samples in metabolic and proteomic analyses?
Yes, serum can be used as a surrogate for tissue samples in metabolic and proteomic analyses, but it may not reflect the full range of metabolic and proteomic changes in the tissue.
How can serum quality be evaluated?
Serum quality can be evaluated based on its clarity, color, and pH. Clear and pale yellow serum with a pH of 7.2-7.4 is considered good quality. The presence of turbidity, clots, or a strong yellow or red color may indicate contamination or hemolysis, and may affect experimental results.
Can serum be used for all types of experiments?
Serum can be used for a wide range of experiments, but its composition may vary depending on the source and preparation method. For certain types of experiments, such as those involving cytokines or growth factors, it may be necessary to use serum-free media or to supplement the media with specific factors.
What is the difference between serum and plasma?
Serum is the liquid portion of blood that remains after blood has been allowed to clot and the clot has been removed, while plasma is the liquid portion of blood that is collected when blood is anticoagulated and then centrifuged to remove blood cells. Plasma contains clotting factors that are removed during the clotting process for serum preparation.
How can serum be sterilized?
Serum can be sterilized using a 0.2 μm filter or by irradiation with gamma rays or ultraviolet light. It is important to use sterile techniques when handling serum to avoid contamination.
Can serum be used for cell culture?
Yes, serum is commonly used as a supplement to cell culture media to provide nutrients and growth factors for cell growth and proliferation. However, it is important to choose a serum that is appropriate for the specific cell type and experiment, and to test the serum for potential contaminants or interfering factors.
Can serum be used for Western blotting?
Yes, serum can be used as a source of primary or secondary antibodies for Western blotting. However, it is important to test the serum for cross-reactivity with other proteins of interest and to optimize the antibody concentration and incubation conditions.
What is the difference between fetal bovine serum (FBS) and adult bovine serum (ABS)?
FBS is derived from the blood of fetal bovine fetuses and is commonly used as a supplement in cell culture media due to its high content of growth factors and nutrients. ABS is derived from adult bovine blood and is used less frequently in cell culture. The composition of FBS and ABS can vary between lots and should be selected based on the specific needs of the experimental system.
