The proper storage of antibodies directly determines their activity and effectiveness! If stored correctly, the activity of most antibodies can be maintained for months or even years. Please always remember to store antibodies properly according to the recommended conditions specified in the instructions.

I. General Antibody Storage Methods

1. Upon receiving the antibody, always centrifuge it at 12,000 rpm for 1-5 minutes before opening the tube for aliquoting and storage.  (If the antibody volume is less than 50 µL, extend the centrifugation time to 5 minutes to ensure all the antibody is spun down.)

2. For most antibodies, the recommended storage method is aliquoting and storing at -20°C or -80°C.

For the vast majority of antibodies, storage at -20°C is entirely sufficient.   (There is no evidence suggesting that storage at -80°C provides additional benefits.)

Aliquoting can minimize the damage caused by repeated freeze-thaw cycles to antibody activity and also reduce the risk of contamination from repeatedly drawing from the same tube. The aliquot volume should ideally be enough for a single experiment, with a minimum of 10 µL per aliquot. This is because smaller volumes are more susceptible to evaporation and loss due to tube wall adsorption. If a thawed aliquot is not fully used, store the remaining solution at 4°C and avoid refreezing! Antibody working solutions should be prepared and used on the same day, and should not be stored at 4°C for more than one day. Never store antibodies in a frost-free freezer. Whenever possible, store antibodies in the inner part of the refrigerator rather than on the door.

3. For most antibodies, short-term storage at 4°C for 1–2 weeks after receipt does not affect their activity.

If the antibody will be used soon (within 1–2 weeks), it is recommended to store it at 4°C to avoid damage caused by repeated freeze-thaw cycles. For long-term storage, it is best to keep the antibody at –20°C or –80°C. The most critical point is to follow the storage instructions provided in the datasheet to ensure proper antibody preservation!

However, for antibodies supplied in ascites fluid, they should be frozen immediately upon receipt! This is because such products contain high levels of proteases, and prolonged storage at 4°C will lead to antibody degradation!

4. Shipping Conditions for Most Antibodies:The standard shipping process typically takes 1–2 weeks and is carried out at 4°C. The primary purpose of 4°C shipping is to avoid damage to antibody activity caused by repeated freeze-thaw cycles (if shipped on dry ice, the antibody arrives frozen and must be thawed for aliquoting—adding an unnecessary freeze-thaw cycle).Therefore, avoid dry ice shipping during transportation!

II. Special Storage Conditions for Antibodies:

1. Enzyme-Linked Antibodies: Always store at 4°C and avoid freezing, as freezing may reduce or completely inactivate the enzyme.

2. Conjugated Antibodies: All conjugated antibodies must be stored in amber tubes or wrapped in foil to protect from light at 4°C. This is especially critical for fluorescently labeled antibodies, which are highly light-sensitive—light protection is essential during all experimental procedures!

3. IgG3 Isotype Controls: Always store at 4°C and never freeze. This antibody is prone to polymerization upon freeze-thaw cycles (avoid any freeze-thawing during storage or shipping). Repeated freezing and thawing can cause denaturation and aggregate formation, significantly reducing its binding capacity!

III. Additional Information on Antibody Storage:

1. Regarding Glycerol Addition for Storage:

Some researchers add 50% glycerol to antibodies to prevent repeated freeze-thaw cycles, as glycerol lowers the freezing point at -20°C.  This method may be suitable for many antibodies.  However, glycerol-containing solutions should not be stored at -80°C, as this exceeds glycerol's freezing point.  If using glycerol for antibody storage, strict aseptic techniques must be followed to avoid contamination!

2. Regarding Protein Stabilizers:

Proteins are less prone to degradation at high concentrations (1 mg/mL or higher), which is why stabilizers like BSA are often added to antibodies. Additionally, these protein additives help minimize antibody loss due to tube wall adsorption. However, if the antibody is intended for labeling purposes, protein stabilizers should not be used, as they may compete with the antibody for binding to the labeling reagent.

3. Regarding the Use of Sodium Azide:

To prevent microbial contamination, sodium azide is commonly added to antibodies (at a final concentration of 0.02% (w/v)).

Sodium azide should not be used under the following conditions:

(1) If the antibody is intended for staining or treating live cells, or for in vivo studies.

(2) While sodium azide is effective against microorganisms, it is also toxic to most other organic matter because it inhibits the mitochondrial cytochrome electron transport system.

(3) When conjugating antibodies containing amino groups: Sodium azide interferes with any conjugation involving amino groups, so it must be removed prior to conjugation. After conjugation, sodium azide can be added to the antibody for preservation, but the concentration should not exceed 0.01%. For antibodies requiring conjugation, thimerosal (merthiolate) can be used as an alternative preservative instead of sodium azide!

4. Methods for Removing Sodium Azide:

Sodium azide can be removed by gel filtration or dialysis! The molecular weight of IgG is 150 kDa (while IgM is ~600 kDa), whereas sodium azide has a molecular weight of only 65 Da. Using a 14 kDa cutoff filter membrane effectively separates sodium azide from the antibody.