Fetal Bovine Serum (FBS) is a widely used supplement in cell culture. It provides essential nutrients, growth factors, hormones, and proteins necessary for cell proliferation, growth, and maintenance. FBS supports a broad spectrum of cell types, making it a common addition to basal growth media. Its unique composition, with low antibody levels and high growth factors, makes it particularly effective for cultivating cells.
Thawing Procedures
Proper thawing of FBS is important to maintain its quality for cell culture. Two primary methods are commonly employed: water bath thawing and refrigerator thawing.
For rapid thawing, a 37°C water bath is frequently used. Remove the FBS bottle from the freezer and allow it to acclimate to room temperature for about 10 minutes. Place the bottle in the water bath, ensuring the water level does not submerge the cap. Gently swirl or shake the bottle every 10 to 15 minutes until completely thawed. This periodic agitation helps distribute salts and proteins, minimizing cryoprecipitates.
Alternatively, thaw FBS in a refrigerator at 2-8°C. This process typically takes overnight. Although slower, refrigerator thawing minimizes thermodynamic stress. Regardless of the chosen method, ensure the FBS is fully thawed before use.
Protecting FBS Quality
Maintaining FBS biological activity requires careful attention. Avoiding repeated freeze-thaw cycles is important for preserving FBS quality. Each cycle can lead to the degradation of proteins and heat-sensitive components, reducing the serum’s ability to support cell growth. This degradation can manifest as increased turbidity or flocculent precipitates.
Overheating the serum compromises its integrity. Thawing at elevated temperatures can cause protein precipitation and inactivate growth factors and nutrients. Thaw the serum thoroughly but gently, preventing excessive heat exposure. Minimizing contamination risk during handling is also important; aseptic techniques should be followed. This includes working in a sterile environment and using sterile equipment.
Storing Thawed FBS
After thawing, proper storage ensures FBS quality and performance. For short-term use, store thawed FBS refrigerated at 2-8°C. Prompt use is recommended, though it can be stable for up to 2-4 weeks. Prolonged refrigeration may lead to protein aggregation, causing visible turbidity or precipitates.
For long-term storage, aliquot FBS into smaller, single-use portions and refreeze. This prevents multiple freeze-thaw cycles on the entire bottle, preserving serum quality. Store aliquots at -20°C or colder, ideally in sterile, sealable containers. Label each aliquot with the date and batch number for traceability, ensuring only the necessary amount is thawed.