Biological samples are important resources for medical research, and their quality determines the accuracy and reliability of clinical results to a large extent. At present, biological samples and their extracted products are mainly stored in two categories: cryogenic and normal temperature. According to the needs of different scientific research, more sample storage methods have also come out. This article will summarize the commonly used sample storage methods and transportation conditions. Save as a favorite for later use.
Sample storage conditions

1. -196℃, -150℃ cryogenic freezing
   Ultra-low temperature cryopreservation is an ideal sample preservation method. Currently, liquid nitrogen (-196°C) is recognized as the most reliable sample preservation method. However, since the sample is completely immersed in liquid nitrogen, free tissue fragments may bring potential risks of cross-contamination. Therefore, the storage method of gas-phase liquid nitrogen (-150°C) was born, which is to place the sample above the liquid nitrogen and surrounded by gas-phase liquid nitrogen, which can well avoid the risk of cross-contamination. In addition, the low temperature effect of -150°C can also be achieved through electric refrigerator refrigeration, thus meeting the long-term storage needs of samples. Because -137°C is the glass transition temperature of water, below this temperature all biochemical reactions in the cell that can cause the degradation of the contents are inactive, thus meeting the requirements for long-term storage.
2. -80℃
   -80°C cryopreservation is an ideal sample preservation method for frozen nucleic acids: in biological sample banks that do not have liquid nitrogen storage conditions, you can also consider using -80°C deep-freezing refrigerators to preserve tissue samples. Studies have shown that at -80°C, DNA yield, integrity and RNA yield can be maintained for up to 7 years without significant changes, but RNA integrity begins to decline after 5 years of cryopreservation. Therefore, it is recommended to aliquot the tissue when storing it, add RNA-specific stabilizer, and freeze it at -80°C, which is more conducive to the preservation of RNA in the tissue.
   Regarding the preservation of proteins, cryogenic freezing is currently the main method, which can well protect its stability. Short term storage can also be kept in a low temperature freezer at -20°C.
3. Storage at room temperature: In view of the inconvenience of transportation and operation of cryogenic freezing, the method of storage at room temperature emerged as the times require. The principle of normal temperature preservation technology can be compared to the dehydration dormancy phenomenon of nematodes. Some special technologies or containers are used to place dehydrated and dried samples in a closed environment, or protective agents are added to biological samples to inactivate relevant enzymes, thereby reaching normal temperature. The purpose of protecting samples from the environment.

Shipping conditions for samples

01 Whole blood/plasma/serum/dried blood tablets

DNA: It can be transported to the laboratory at room temperature within 24 hours, and transported to the laboratory within 72 hours at 2-8°C. Transportation for 72 hours and longer needs to be at -20°C.
RNA: Separate plasma within 4 hours, transport to the laboratory within 5 days, and store at 2-8°C. Transport for 5 days or longer must be at -20°C.

Dried blood tablets can be shipped at room temperature.

02 Alveolar lavage fluid

It can be transported to the laboratory at room temperature within 24 hours, and must be transported under refrigerated conditions at 2-8°C within 72 hours. Transport for 72 hours and longer requires -70°C or more stringent conditions.

03 bone marrow

Bone marrow specimens should be transported at 2-8°C and if used for RNA analysis, RNA stabilizers should be added.

04 Cheek cells

Nucleic acids can exist stably for 1 week at room temperature and can be transported at room temperature. To detect RNA, they need to be placed in an RNA stabilizer.

05 Lymphocyte layer

Lymphocytes isolated from blood need to be refrigerated and transported at 2-8°C. If they cannot be extracted in time, they should be stored below -70°C.

06 cerebrospinal fluid

DNA virus detection: needs to be transported at 2-8 degrees Celsius and should be stored at -20 degrees Celsius or -70 degrees Celsius or lower.
RNA analysis: Immediately cool down on ice and transport to the laboratory on dry ice.

07 Fine needle aspirate

DNA virus detection: It needs to be transported at 2-8℃ and should be stored at -20℃ or -70℃ or lower.
RNA analysis: Place on ice immediately to cool down or place in RNA stabilizer for transport.

08 Organization

DNA Analysis: Fresh tissue should be placed immediately at -20°C and kept on ice for transport storage.

RNA analysis: Fresh tissues are quickly frozen in liquid nitrogen immediately after collection for transportation and storage.

Paraffin-embedded tissue can be transported and stored at room temperature.

09 sputum

It can be transported to the laboratory at room temperature within 30 minutes, otherwise it should be transported at 4-8°C.

010 Feces

It can be collected with the help of feces collection box and feces collection tube, and a sample the size of a soybean grain is enough. Carry out nucleic acid extraction or cryopreservation at -80°C within 4 hours.

011 Cervical and urethral swabs

Ship in the shipping medium recommended by the test reagent manufacturer.

012 Plant tissue samples

Collect fresh samples with normal body shape and put them into sample bags and mark them; if the samples contain soil, they generally need to be washed, then dried and nucleic acid extracted as soon as possible; transported and stored at room temperature or -20°C.

It should be noted here that samples should be stored under stable conditions and repeated freezing and thawing should be avoided.