Freezing Bags: A Full-process Solution for Low-temperature Storage of Biological Samples

 

In the fields of biomedical research and cell therapy, freezing bags, as core storage tools, undertake the important mission of maintaining the viability of biological samples. Through the combination of materials science and functional design, these professional containers achieve full-course protection from the ultra-low temperature of -196°C to daily operations, providing a reliable safety barrier for biological materials such as cells and tissues.

 

I. Key Materials and Low-temperature Performance

The core material of freezing bags is mostly ethylene-vinyl acetate (EVA). Its unique molecular structure enables it to maintain flexibility at extremely low temperatures, avoiding the risk of breakage due to embrittlement. Some high-specification products also compound multiple layers of polymer materials on the basis of EVA to further optimize impact resistance and sealing performance. This structural design allows freezing bags to withstand long-term storage in liquid nitrogen environments and adapt to frequent freeze-thaw cycles.

To ensure the absolute safety of samples, freezing bags need to be sterilized by gamma irradiation to eliminate microbial contamination such as bacteria and fungi. Some advanced products are also equipped with double-sealed ports and leak-proof diaphragms to minimize the risk of cross-contamination during operation.

 

II. Multi-scenario Applications and Technical Adaptation

1. Cell Therapy Field

In advanced therapies such as CAR-T, freezing bags are used for the freezing and transportation of hematopoietic stem cells and immune cells. Their large-capacity design (common specifications range from 25 mL to 500 mL) can meet the batch processing requirements of clinical-grade cell preparations, and the inner wall treatment to prevent biological residues reduces cell loss.

2. Construction of Biological Sample Banks

For precious biological resources such as tumor tissues and DNA samples, freezing bags provide a stable storage environment for decades. Some models support electronic chips or QR code identification through optimized label area design, facilitating the docking with information management systems.

3. Regenerative Medicine Research

Researchers use freezing bags to preserve 3D bioprinted tissues. Their open-port design supports seamless docking with bioreactors, significantly improving the preparation efficiency of tissue engineering products.

 

III. Technical Parameter Guide for Product Selection

Users need to match product specifications according to specific scenarios:

- Temperature Tolerance Range: It should cover the lowest temperature of the usage scenario (e.g., -196°C for liquid nitrogen tank storage).

- Sealing Performance: It is recommended to choose a medical-grade sealing standard with a leakage probability of <0.01%.

- Volume Accuracy: For therapeutic-level applications, the error rate is required to be ≤2%, and it can be relaxed to 5% for research-level applications.

- Compliance Certification: It is necessary to have the ISO13485 medical device quality management system certification.

 

IV. Operation Specifications and Maintenance Points

1. When filling samples, 10% - 15% expansion space should be reserved to prevent rupture caused by volume expansion during freezing.

2. A pressure test should be conducted before long-term storage: Inject air and then immerse it in an ethanol solution to observe whether bubbles are generated.

3. Special metal protective boxes should be used during transportation to avoid mechanical extrusion and temperature fluctuations.

4. Programmed temperature control equipment is recommended for the thawing operation, and the heating rate per minute should be controlled at 1 - 3°C.