Secondary Antibodies
Our secondary antibody range covers rabbit, mouse, goat, donkey and chicken hosts across whole IgG (H+L), light chain-specific, Fab fragment-specific and Fc fragment-specific formats, conjugated to HRP, AP, biotin, gold, Alexa Fluor™, DyLight™ and ABflo® dyes for western blot, ELISA, IHC, ICC/IF and flow cytometry.
Browse Secondary AntibodiesFeatured Secondary Antibodies
A standard whole-IgG (H+L) secondary detects both the heavy and light chains of a primary antibody, and only works if the primary carries a conventional Fc region. The two products below cover cases outside that: a secondary raised against a nanobody rather than an Fc region, and a secondary that reads the light chain only.
Rabbit Anti-Llama VHH Antibody {HRP} (STJS000855)
Camelid nanobodies (VHH domains) have no conventional IgG Fc region, so a standard anti-Fc secondary will not detect them. This secondary is raised directly against the VHH domain, validated by western blot at 1:500-1:1000. An unconjugated format is also available.
View product →
Goat Anti-Mouse IgG Light Chain Antibody {HRP} (STJS001198)
Binds only the light chain of mouse IgG, not the heavy chain. Useful when a co-immunoprecipitation or hybridoma western blot would otherwise pick up heavy-chain signal from the IP antibody itself. Validated at 1:5000 dilution against mouse IgG.
View product →Rabbit, Mouse, Goat, Donkey and Chicken Secondary Antibodies
The secondary antibody should be raised in a host species different from the primary antibody's own host, and against its isotype, so it can be matched to the primary and the reactivity required. Each host below is validated on its own product datasheet.
Browse by host reactivity
Species-specific listings for the most requested secondary antibody reactivities:
Rabbit host secondary antibodies
| Specificity (primary antibody target) | Target | Available formats | Research applications |
|---|---|---|---|
| Whole IgG (H+L) | Cat, Chicken, Cow, Dog, Donkey, Duck, Goat, Guinea Pig, Horse, Human, Monkey, Mouse, Pig, Rat, Sheep | Whole IgG detection, providing versatile detection for multiple assays | |
| VHH nanobodies | Llama | Specific for nanobody domains; key for camelid antibody studies | |
| Anti-IgG Fc-specific Fragment antibody | Human | Binds only to the Fc region of the primary antibody and is useful in avoiding certain types of non-specific binding |
Mouse host secondary antibodies
| Specificity (primary antibody target) | Target | Available formats | Research applications |
|---|---|---|---|
| Whole IgG (H+L) | Chicken, Duck, Human, Monkey, Pig, Rabbit | Whole IgG detection, providing versatile detection for multiple assays | |
| Light chain-specific antibody | Human, Rabbit | Reduces heavy chain noise in WB; suitable for subclass and fragment analysis | |
| Fab Fragment-specific antibody | Human | Reduces non-specific binding in hybridoma or closely related species assays | |
| Anti-IgG Fc-specific Fragment antibody | Human, Rabbit | Binds Fc region only; useful to eliminate Fc-mediated background signal |
Goat host secondary antibodies
| Specificity (primary antibody target) | Target | Available formats | Research applications |
|---|---|---|---|
| Whole Ig isotypes (H+L), incl. IgG, IgM, IgA, IgY (chicken) | Chicken, Guinea Pig, Human, Mouse, Pig, Rabbit, Rat | Whole IgG detection, providing versatile detection for multiple assays | |
| Light chain | Mouse | Reduces heavy chain noise in WB; subclass and fragment characterisation | |
| Fab Fragment | Human | Reduced non-specific binding to Fc receptors, enabling cleaner staining; useful for blocking endogenous immunoglobulins | |
| Anti-IgG Fc-specific Fragment antibody | Human, Rabbit | Binds only to the Fc region of the primary antibody and is useful in avoiding certain types of non-specific binding |
Chicken secondary antibodies
| Specificity (primary antibody target) | Target | Available formats | Research applications |
|---|---|---|---|
| Whole IgG (H+L) or IgY (chicken) | Chicken, Goat | Detects chicken IgG; used for chicken primary antibodies |
Donkey secondary antibodies
| Specificity (primary antibody target) | Target | Available formats | Research applications |
|---|---|---|---|
| Whole IgG (H+L), including highly cross-adsorbed | Goat, Mouse, Rabbit, Rat | Cross-adsorbed secondary antibodies are available, which reduce cross-reactivity and non-specific binding |
Available Conjugation Types
Unconjugated secondaries suit classic two-step indirect detection. Conjugated formats carry the label directly on the antibody, chosen according to the detection system in use.
HRP-Conjugated Secondary Antibodies
Well-suited for western blotting and colourimetric detection. Compatible with chemiluminescent and fluorescent substrates.
View HRP secondaries →AP-Conjugated Secondary Antibodies
Offers high sensitivity and stable signal development, producing a strong, long-lasting colorimetric or chemiluminescent signal with low background.
View AP secondaries →Biotin-Conjugated Secondary Antibodies
Also known as Vitamin H or B7, covalently attached to secondary antibodies, allowing tight binding to streptavidin or avidin.
View biotin secondaries →Gold-Conjugated Secondary Antibodies
Gold nanoparticle-conjugated antibodies suitable for electron microscopy and lateral flow assays, offering high-resolution imaging.
View gold secondaries →Alexa Fluor™-Conjugated Secondary Antibodies
High performance dyes ranging from blue to near-infrared, significantly brighter than traditional fluorophores, for longer imaging sessions and signal capture.
View Alexa Fluor secondaries →DyLight™-Conjugated Secondary Antibodies
High photostability and broad spectral range, suitable for long exposure imaging and high signal-to-noise ratios.
View DyLight secondaries →Secondary Antibodies for Western Blot
HRP-conjugated secondaries are used with chemiluminescent substrates for protein detection on blotted membranes, typically at 1:5,000 to 1:20,000. The products below are all validated by western blot on the datasheet.
Secondary Antibodies for ELISA
HRP- and biotin-conjugated secondaries are used as detection reagents in sandwich and indirect ELISA formats, giving enzyme-mediated signal amplification. The products below list ELISA among their validated applications.
Secondary Antibodies for IHC
HRP-conjugated secondaries paired with a chromogenic substrate are the standard detection route for immunohistochemistry on paraffin-embedded tissue. The products below list IHC-P among their validated applications.
Secondary Antibodies for Flow Cytometry and ICC/IF
Fluorophore-conjugated secondaries are used for cell-surface and intracellular staining in flow cytometry, and for direct visualisation of target localisation by immunofluorescence and immunocytochemistry. The Alexa Fluor™ products below are all validated for fluorescence microscopy and flow cytometry.
Matching a Conjugate to an Existing Fluorescence Channel
If a panel already uses a dye like FITC or Cy3, the tables below show the closest Alexa Fluor™ or DyLight™ equivalent and its excitation/emission wavelength, so a new secondary can be picked to sit in the same channel.
Alexa Fluor™ Secondary Antibody Conjugates
| Name of Dye | Excitation/Emission (nm) | Replaces | Colour |
|---|---|---|---|
| Alexa Fluor 350 | 343/441 | Coumarin (AMCA) | Blue |
| Alexa Fluor 405 | 401/422 | Pacific Blue | Blue |
| Alexa Fluor 488 | 499/520 | FITC, Cy2 | Green |
| Alexa Fluor 532 | 534/553 | Rhodamine Green | Yellow |
| Alexa Fluor 555 | 553/568 | Cy3, TRITC | Orange |
| Alexa Fluor 568 | 579/603 | Rhodamine Red | Red |
| Alexa Fluor 594 | 590/618 | Texas Red | Red |
| Alexa Fluor 633 | 631/650 | Cy5 | Far Red |
| Alexa Fluor 647 | 650/671 | Cy5 | Far Red |
| Alexa Fluor 660 | 663/691 | Cy5.5 | Near-IR |
| Alexa Fluor 680 | 681/704 | IRDye 680, Cy5.5 | Near-IR |
| Alexa Fluor 750 | 752/776 | Cy7 | Near-IR |
| Alexa Fluor 790 | 782/805 | IRDye 800CW | Near-IR |
DyLight™ Secondary Antibody Conjugates
| DyLight Dye | Excitation (nm) | Applications | Comparable Dyes |
|---|---|---|---|
| DyLight 350 | ~350 | IF, FC | Alexa Fluor 350, AMCA |
| DyLight 405 | ~405 | WB, IF, FC | Alexa Fluor 405, Pacific Blue |
| DyLight 488 | ~488 | WB, IF, FC | Alexa Fluor 488, FITC |
| DyLight 550 | ~550 | WB, IF | Alexa Fluor 546, Cy3 |
| DyLight 594 | ~594 | IF, FC | Alexa Fluor 594, Texas Red |
| DyLight 633 | ~633 | WB, IF | Alexa Fluor 633, Cy5 |
| DyLight 649 | ~649 | IF, FC | Alexa Fluor 647, Cy5.5 |
| DyLight 680 | ~680 | WB, IF, FC | Alexa Fluor 680, IRDye 680 |
| DyLight 800 | ~800 | WB, IF, FC | Alexa Fluor 790, IRDye 800CW |
ABflo® Secondary Antibody Conjugates
| ABflo® Dye | Excitation / Emission (nm) | Applications | Comparable Dyes |
|---|---|---|---|
| ABflo® 405 | 405 approx. | IF, ICC, FC | Alexa Fluor 405, DyLight 405 |
| ABflo® 488 | 488 approx. | IF, ICC, FC | Alexa Fluor 488, FITC, DyLight 488 |
| ABflo® 555 | 555 | IF, ICC, FC | Alexa Fluor 555 |
| ABflo® 594 | 594 | IF, ICC, FC | Alexa Fluor 594, Texas Red |
| ABflo® 647 | ≈647 | IF, ICC, FC | Alexa Fluor 647, Cy5, DyLight 649 |
| ABflo® 750 | 750 / 775 | IF, ICC, FC | Alexa Fluor 750, Cy7, APC-Cy7 |
Choosing, Diluting and Troubleshooting Your Secondary Antibody
Selecting the right secondary comes down to three variables: target species, isotype and conjugation, matched against the primary antibody and detection system in use.
Why use secondary antibodies?
Signal amplification: multiple secondary antibodies can bind a single primary antibody, increasing detection sensitivity, especially for low-abundance targets. Versatility: compatible with a wide range of detection systems and formats. Multiplexing: enables simultaneous detection of multiple targets using different fluorophores.
Choosing the right secondary antibody
Target species should match the primary antibody host species. Isotype should match the primary antibody isotype. Conjugation should be chosen according to application needs. All secondary antibodies in the range are affinity-purified, giving high specificity and low background.
Optimising dilution
Primary antibody: typical dilution 1:100 to 1:1,000. Secondary antibody: recommended dilution 1:500 to 1:2,000 for immunofluorescence. Excessive concentration can lead to high background or non-specific staining.
Troubleshooting tips
Use cross-adsorbed secondary antibodies, which have additional purification steps to remove off-target immunoglobulin, reducing cross-reactivity. Include negative controls (no primary antibody) to assess background. Adjust blocking and washing steps to minimise immunofluorescence background.
Backed by the SJL guarantee
Our antibodies support demanding applications that require high specificity, producing reproducible results suitable for academic research and publication. They also provide batch-to-batch consistency and an unlimited supply, making them suitable for long-term studies. If our products fall below the standard you expect, we will replace or refund them.
View our antibody guarantee →Looking for a Specific Target?
Browse the full secondary antibody range, including unconjugated, HRP-, AP-, biotin-, gold-, Alexa Fluor™-, DyLight™- and ABflo®-conjugated formats across rabbit, mouse, goat, donkey and chicken hosts.
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