Yingtai: Pre-cooling Temperature Requirements for Different Samples

Yingtai: Pre-cooling Temperature Requirements for Different Samples  

Biological Samples  

1. Nucleic Acid-Related  

   - DNA Extraction Temperature: 2–4°C (to inhibit DNase activity)  

     Special Requirement: Lysis buffer containing phenol/chloroform must be pre-cooled to 4°C to reduce volatility.  

   - RNA Isolation Temperature: 0–2°C (preferably operated on ice)  

     Key Point: If using TRIzol, avoid light exposure and pre-cool throughout the process.  

2. Proteins and Organelles  

   - Soluble Proteins Temperature: 4°C (to prevent thermal denaturation)  

     Buffer: PBS containing protease inhibitors must be refrigerated in advance.  

   - Mitochondria/Lysosomes Temperature: 4°C with gradient cooling (first equilibrate at 4°C for 30 minutes, then cool to the target temperature)  

     Protectant: Add 250 mM sucrose to maintain osmotic pressure.  

3. Microorganisms and Cells  

   - Bacterial Cultures Temperature: 4°C (for log-phase cells) or –20°C (for long-term storage)  

     Note: Gram-negative bacteria should avoid repeated freeze-thaw cycles.  

   - Mammalian Cells Temperature: 4–10°C (for live cell isolation) or flash-freezing in liquid nitrogen (for long-term storage).  

Special Scenario Temperature Control Guidelines  

- Clinical Samples  

  - Serum/Plasma: Pre-cool at 4°C (freezing is prohibited to prevent lipoprotein denaturation).  

  - Urine Cells: Store at 2–8°C for no more than 24 hours.  

- Extreme Temperature Requirements  

  - Ultra-Low Temperature (–80°C): Suitable for viral RNA preservation.  

  - Cryogenic (–196°C Liquid Nitrogen): For long-term stem cell storage, programmed cooling is required.  

Operational Risks and Validation  

- Temperature Validation Tools:  

  - Infrared thermometer (for detecting rotor surface temperature).  

  - Wireless temperature logger.  

- Common Mistakes:  

  ❌ Direct freezing of water-containing samples (causes ice crystal damage).  

  ✅ Correct: Samples containing cryoprotectants (e.g., 10% DMSO) can be pre-cooled at –80°C.