Custom Antibodies: Storage & Handling

Genosphere custom antibodies, including antisera, purified polyclonal and monoclonal antibodies, and chicken IgY, are supplied lyophilised for stability during transport and storage. The guidelines below will help preserve antibody activity from receipt to experiment. Lot-specific details, including reconstitution volume and final concentration, are given in the production report supplied with your project.

At a glance

Shipment: ambient temperature
Lyophilised, short term: 2–8 °C
Lyophilised, long term: −20 °C, stable for at least one year
Reconstituted, short term: 2–8 °C, 1–2 weeks (sterile solutions)
Reconstituted, long term: −20 °C or below, in single-use aliquots, up to 12 months
Preservative: 0.02% sodium azide (unless otherwise stated)

Lyophilised antibodies: on arrival

Our lyophilised antibodies are shipped at ambient temperature. On arrival, check that the vials are intact and store them under the conditions indicated above. Reconstitute only when you are ready to use the antibody or prepare aliquots for storage.

Reconstitution

Reconstitute each vial with sterile deionised water, using the exact volume stated in your production report. The final concentration is also given in the report.

Antisera and pre-immune sera (rabbit, guinea pig, rat, mouse): reconstitution restores the original serum volume.
Purified antibodies (total IgG, affinity-purified and monoclonal antibodies): reconstitution restores the original buffer formulation at the stated concentration.
Chicken IgY (pre-immune and purified): reconstitute as specified in your production report.

Storage and stability

Before reconstitution: store at 2–8 °C. For long-term storage, keep at −20 °C, where the product remains stable for at least one year.

After reconstitution:

At −20 °C or below: up to 12 months for antisera and concentrated antibody solutions (≥ 1 mg/ml)
At 2–8 °C: 1–2 weeks for sterile solutions

How to store monoclonal and polyclonal antibodies

The same basic storage principles apply to monoclonal and polyclonal antibodies. Stability depends on the individual antibody, its concentration and its formulation.

Polyclonal antisera and purified polyclonal antibodies contain antibodies that recognise different epitopes. Loss of activity in some antibody populations may reduce the overall signal; the effect depends on which populations contribute to the assay.
Monoclonal antibodies recognise a single epitope. Loss of binding activity can reduce or eliminate the signal, but monoclonal antibodies are not necessarily less stable in storage than polyclonal antibodies.
Antiserum contains abundant serum proteins that can help stabilise antibodies during storage.
Purified antibodies can be more susceptible to surface adsorption and loss of activity when diluted, particularly without a carrier protein.

Avoiding freeze–thaw damage

Repeated freezing and thawing can cause aggregation and loss of activity. For frozen storage, divide the reconstituted solution into single-use aliquots and thaw only what you need.

Good storage practice

Use low-protein-binding tubes for aliquots, especially for purified antibodies at low concentration. Where practical, keep aliquots to 10 µl or more to limit evaporation and surface loss.
Protect conjugated antibodies from light, particularly fluorophore conjugates. Enzyme (HRP, AP) and protein-fluorophore (PE, APC) conjugates often require storage at 2–8 °C rather than freezing; follow the instructions supplied with each conjugate.

Antibody storage buffer and working dilutions

Reconstitution with the specified volume of sterile deionised water restores the supplied formulation, so no additional storage buffer is needed. Further considerations apply when you dilute an antibody for use.

Buffer and pH. PBS or TBS at pH 7.2–7.6 is suitable for many antibodies; choose a buffer compatible with your assay.
Carrier protein. Diluted antibodies can adsorb to tube surfaces, reducing the effective antibody concentration. If you need to store a diluted antibody, a carrier protein such as 0.1–1% BSA can help limit this loss, particularly for purified antibodies at low concentration. Omit BSA if it interferes with your assay or if you plan to conjugate the antibody.
Glycerol. Where compatible with the antibody and intended application, glycerol can be added to a final concentration of 50% (v/v) to keep the stock liquid at −20 °C. Starting from a glycerol-free stock, mix equal volumes of antibody solution and high-purity glycerol suitable for laboratory use. This halves the antibody concentration. Store these stocks at −20 °C; at −80 °C, they may freeze.
Working dilutions in assay buffer are best prepared on the day of use.

Weaker signal? Where to look first

A weaker signal can reflect changes in the antibody, the sample or the assay conditions. Check the following points:

Has the antibody undergone repeated freeze–thaw cycles? Compare with a fresh aliquot if available.
How long has the reconstituted antibody been at 2–8 °C? Follow the 1–2-week storage guidance above; if this period has been exceeded, compare with an aliquot stored frozen as recommended.
Was the antibody stored after dilution without a carrier protein? Surface adsorption may have reduced its effective concentration.
Is the solution cloudy, or is there a precipitate? Cloudiness or precipitation may indicate aggregation or contamination. Centrifugation can remove insoluble material, but does not necessarily restore antibody activity.
Is there azide in an HRP conjugate or substrate solution? It may inhibit the detection reaction.
Have the sample or assay conditions changed? Review lysate preparation, fixation, antigen retrieval and detection reagents, and include a suitable positive control where possible.

For the peptides used as antigens, see peptide storage & handling. For a new project, see custom antibody development.

Research use only

All products are supplied for research use only and are not intended for medical, diagnostic or veterinary use.

Any questions? Our technical team will be happy to help.