Donkey Serum | EU Origin | sterile filtered

Why is donkey serum the preferred blocking reagent for multiplex IHC panels?

In multiplex IHC and immunofluorescence, multiple primary antibodies from different host species are detected with species-specific secondary antibodies. When the panel uses secondaries raised in multiple species — for example, anti-rabbit and anti-goat secondary antibodies — the blocking serum must not introduce cross-reactive proteins from either of those species. Rabbit serum would interfere with the anti-rabbit secondary; goat serum would interfere with the anti-goat secondary. Normal Donkey Serum (NDS) is phylogenetically neutral toward mouse, rat, rabbit, goat, sheep, horse, and human — a single NDS blocking step covers the entire secondary antibody panel without species conflicts. This is why NDS is the standard blocking reagent for multiplex IHC protocols across most major research and diagnostic laboratories.

When is Normal Donkey Serum NOT suitable as a blocking reagent?

NDS should not be used when the panel includes secondary antibodies raised in donkeys (anti-donkey secondaries), or when the primary antibody itself is donkey-derived. In either case, NDS proteins would compete with the donkey-derived antibody for binding and elevate non-specific background. For such panels, a different blocking serum — matched to the phylogenetic distance from all species present in the assay — must be selected. If the panel uses only rabbit and mouse primaries with anti-rabbit and anti-mouse secondaries, goat serum is sufficient; NDS is specifically required when goat secondaries are also included, or when maximum phylogenetic distance from all panel species is needed.

Can Normal Donkey Serum be used as a universal antibody diluent?

Yes — dilute NDS to 1–2% in PBS-T (phosphate buffered saline with 0.05–0.1% Tween-20) for use as a universal antibody diluent for primary and secondary antibodies across all species in your panel. Using a species-neutral diluent prevents additional non-specific background introduced by the diluent itself, and maintains consistent antibody activity throughout the incubation. This is particularly useful in multiplex IF protocols where all antibody incubations must be carried out under identical background conditions. The same NDS blocking stock can be diluted further for use as diluent, simplifying reagent preparation.

Is heat inactivation of Normal Donkey Serum available, and when is it needed?

Yes — heat inactivation (56 °C, 30 min) is available on request. It destroys complement proteins and is required when complement activation by the serum blocking reagent would interfere with the assay — for example, in complement-sensitive cell-based assays or when the serum is used as a matrix control in complement fixation protocols. For standard IHC, IF, Western blot, and ELISA blocking applications, non-heat-inactivated NDS is used. Please specify the required form when requesting a quote or sample.

What documentation is supplied with EU Origin Normal Donkey Serum?

Every order includes a Certificate of Analysis (CoA) and Certificate of Origin (CoO). Safety Data Sheet (SDS) and additional documentation — sterility test reports and origin declarations — are available on request. Products are handled at ISO 9001 and ISO 13485 certified partner facilities. Batch reservation for up to 36 months is available on request, ensuring lot-to-lot consistency for long-term multiplex panel development, diagnostic kit manufacturing, and antibody validation programmes.