Core Steps and Key Points for First-Time Use of New Serum

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July 08, 2026

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Step 1: Pre-Use Preparation & Validation Test

This step determines the success of cell culture. Never apply new serum directly to precious cell lines.

1. Receipt Inspection: Immediately check the inner and outer packaging for damage or leakage upon arrival. The serum should be fully frozen or in an ice-water mixture state. Contact the supplier if complete thawing is observed.

2. Proper Thawing & Aliquoting:
Procedure: Transfer frozen serum from -20°C to a 4°C refrigerator for overnight thawing, then place at room temperature for approximately 30 min to achieve complete dissolution. Gently swirl the bottle throughout the process to homogenize temperature and components evenly.

Prohibited Operation: Never rapidly thaw frozen serum in a 37°C water bath, as this will trigger massive protein precipitation.

Aliquoting: Once fully thawed, perform sterile aliquoting according to single-use volume immediately and store aliquots at -20°C. This effectively prevents activity component degradation caused by repeated freeze-thaw cycles.

3. Mandatory Parallel Pre-Experiment: Conduct side-by-side comparison tests between old and new serum using your target cell line.
Test Readouts: Observe cells for at least 2–3 passages, focusing on normal cell morphology, proliferation rate, viability, and specific functional indicators (e.g., transfection efficiency, target protein secretion).

Step 2: Formal Serum Replacement & Gradual Transition

Only proceed to replace serum for main culture cells after passing pre-experiment validation, adopting a gradient transition strategy.

1. Operation Example: When preparing complete culture medium, implement volume gradient transitions: Old Serum : New Serum = 7:3 → 5:5 → 3:7. Stabilize cell culture for 1–2 passages at each ratio, then fully switch to new serum at the final stage.

2. Transition Monitoring: Closely monitor cell status during this phase. Suspend serum replacement or revert to the previous mixing ratio once any abnormal cellular phenotypes appear.

Step 3: Post-Replacement Management

1. Record-Keeping: Document the serum brand, lot number, activation date, and all cellular performance data post-replacement for full traceability.

2. Storage Specification: Store aliquoted serum at -20°C or lower temperatures to avoid repeated freeze-thaw cycles. Thawed serum stored at 4°C should be used within 1 month at maximum.

Other Critical Notes:

Common issues encountered during serum replacement and application are summarized below:

1. Serum Precipitates: Minor flocculent or granular precipitates (observed as "tiny black dots" under microscope) formed after thawing are mostly fibrin or lipoprotein precipitates, a common physical phenomenon. Standard thawing procedures described above can minimize precipitate formation. Minor precipitates generally do not interfere with cell culture performance. If precipitate removal is required, centrifuge serum at 400–600 g for 5 min and collect the supernatant; direct filtration of undiluted serum is not recommended to prevent membrane clogging.

3. Heat Inactivation Guidelines: Most commercially available Fetal Bovine Serum (FBS) does not require heat inactivation. The inactivation process (56°C, 30 min) degrades partial growth factors and increases precipitate generation. Perform heat inactivation only if your experimental protocol specifies complement inactivation requirements.

4. Serum Color Appearance: Qualified FBS exhibits pale yellow or light reddish color. Color intensity correlates with hemoglobin content and does not affect product quality under normal circumstances. Discard serum with abnormal deep red color or visible turbidity.

Category	Catalog No.	Product Name	Lead Time	Specification
Fetal Bovine Serum	abs981	Premium Grade Fetal Bovine Serum	In Stock	500mL
	abs972	Superior Grade Fetal Bovine Serum	In Stock	500mL
	abs974	Standard Grade Fetal Bovine Serum	In Stock	500mL
	abs983	General Grade Fetal Bovine Serum	In Stock	500mL
Special Processed Fetal Bovine Serum	abs993	Exosome-Depleted Fetal Bovine Serum	In Stock	50mL
	abs973	Gamma-Irradiated Superior Grade FBS	In Stock	500mL
	abs975	Gamma-Irradiated Standard Grade FBS	In Stock	500mL
	abs982	Dialyzed Premium Grade FBS	In Stock	500mL
	abs945	Dialyzed Superior Grade FBS	In Stock	500mL
	abs984	Lipid-Depleted Fetal Bovine Serum	4 Weeks	500mL
	abs943	Charcoal-Stripped Fetal Bovine Serum	In Stock	500mL
	abs944	Heat-Inactivated Fetal Bovine Serum	In Stock	500mL
Special Application Customized FBS	abs941	Tetracycline-Free FBS for Tet-On/Tet-Off System	In Stock	500mL
	abs936	Cell Fusion Specialized FBS	In Stock	500mL
	abs938	Stem Cell Specialized FBS	1–2 Weeks	500mL
	abs940	293T Cell Specialized FBS	1–2 Weeks	500mL
	abs942	Insect Cell Specialized FBS	1–2 Weeks	500mL
	abs985	Low-IgG Specialized FBS	In Stock	500mL

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Absin Bioscience Inc.

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