What is the difference between a monoclonal and a polyclonal primary antibody?

Monoclonal antibodies bind a single epitope on the target protein, giving consistent and reproducible signal across experiments. Polyclonal antibodies recognise multiple epitopes, producing stronger overall signal — useful for detecting low-abundance targets in IHC or IF. For quantitative applications such as ELISA and flow cytometry, monoclonals are generally preferred for their specificity.

How do I choose a primary antibody for western blot?

Confirm the antibody has a validated western blot application listed in its datasheet, and that the species reactivity matches your sample. Check the datasheet image for a clean band at the expected molecular weight. For quantitative western blot, recombinant or KO-validated antibodies provide the highest confidence in specificity.

What does KO-validated mean?

KO-validated antibodies have been tested in knockout cell line models where the target gene is completely inactivated. A confirmed absence of signal in the knockout sample demonstrates the antibody binds specifically to the intended target and not to off-target proteins. This is considered the most rigorous form of antibody validation.

Do you offer trial sizes before committing to a full vial?

Yes. Over 13,000 antibodies in our catalogue are available as 20 µl trial vials through the Antibody Validation Project (AVP). If you return your results, we will refund the cost of the trial size. Look for the AVP badge on individual product pages.

Which primary antibody format is best for immunohistochemistry?

For FFPE tissue sections, rabbit polyclonal antibodies typically perform well due to their multi-epitope recognition. Our IHC-Guaranteed antibodies have been specifically validated in IHC with confirmed staining data. Always refer to the individual datasheet for recommended dilutions and antigen retrieval conditions for your tissue type.

Primary Antibodies

Primary antibodies validated for western blot, IHC, immunofluorescence and ELISA

St John's Laboratory offers more than 60,000 primary antibodies covering the full range of research targets, applications and species. Our catalogue includes rabbit and mouse monoclonals, goat and rabbit polyclonals, recombinant antibodies, and KO-validated formats — available as trial sizes, standard vials, concentrates and bulk quantities.

Browse primary antibodies

60,000+

Primary antibodies in catalogue

17+

Validated species

1yr

Guarantee on all antibodies

By type By application By validation Choosing the right antibody

Antibody format

Monoclonal, polyclonal and recombinant formats

Select a format based on your application requirements. Monoclonals offer high specificity to a single epitope; polyclonals provide broader signal amplification across multiple epitopes; recombinant antibodies deliver consistent lot-to-lot reproducibility without animal use.

Monoclonal antibodies

Mouse and rabbit monoclonals targeting a single epitope. Suitable for quantitative applications including flow cytometry, ELISA and western blot where specificity and reproducibility are essential.

Polyclonal antibodies

Rabbit, goat and sheep polyclonals raised against multiple epitopes. Higher sensitivity in IHC and IF where signal amplification is a priority.

Recombinant antibodies

In vitro-produced monoclonals from synthetic genes. No animal or hybridoma dependency. Consistent sequence and specificity across batches — recommended for publication-quality data.

Conjugated primary antibodies

HRP-, FITC- and fluorophore-conjugated formats for direct detection without a secondary antibody. Reduces background in multiplex IF and flow cytometry workflows.

Application

Antibodies by validated application

Every antibody in our catalogue lists only confirmed validated applications. Always refer to the individual datasheet for recommended dilutions and lot-specific validation data before use.

Western blot (WB)

The largest validated application in our range. Antibodies are tested at confirmed dilutions across multiple cell line and tissue lysates, with representative blot images included in the datasheet.

Immunohistochemistry (IHC)

Validated for formalin-fixed paraffin-embedded (FFPE) and fresh-frozen tissue. Our IHC-Guaranteed range offers performance assurance backed by an explicit validation standard.

Immunofluorescence (IF)

Antibodies confirmed for use in fixed-cell and live-cell imaging workflows, with representative IF images available in datasheets. Compatible with most fluorescent secondary antibody platforms.

Flow cytometry (FC)

Validated for surface and intracellular staining in suspension cell populations. Both unconjugated formats for use with secondary antibodies and directly conjugated primaries are available.

Validation level

Selecting by validation standard

Antibody performance varies by lot, target and tissue type. Filter by validation level to match your experimental requirements for specificity and reproducibility.

KO-validated antibodies

Tested in knockout cell line models where the target gene is fully inactivated. Absence of signal in KO samples confirms target specificity. Recommended for high-impact studies and publications requiring rigorous antibody validation.

IHC-Guaranteed antibodies

Each antibody in this collection has been validated in IHC with confirmed tissue staining results. If it does not perform as specified, contact our technical team for resolution or replacement.

Trial size antibodies

20 µl trial vials for over 13,000 antibodies in our Antibody Validation Project (AVP). Test the antibody in your system before committing to a full size. Return your results for a refund on the trial cost.

PTM-specific antibodies

Phospho, acetyl and methyl antibodies that detect proteins at specific post-translational modification states. Essential for studying kinase pathways, epigenetic regulation and cell signalling events.

Monoclonal or polyclonal?

Monoclonal antibodies bind a single epitope, giving consistent, reproducible signal — the preferred choice for quantitative assays, ELISA, and flow cytometry where cross-reactivity must be minimised. Polyclonal antibodies recognise multiple epitopes on the same target, producing stronger signal amplification — often more effective for low-abundance targets in IHC and IF. If your target is denatured under SDS-PAGE conditions, polyclonals are generally more tolerant of epitope disruption.

Key factors when selecting a primary antibody

Confirm the validated application matches your experimental method
Check species reactivity against your sample source
Review datasheet images from your target application before ordering
For reproducibility-critical studies, choose recombinant or KO-validated formats
Match host species to your secondary antibody to avoid cross-reactivity
Consult individual datasheets for confirmed working dilutions — do not assume

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