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Labeled Antibodies

Labels for detecting antibodies

Antibodies are labeled with various substances for detection. When using a commercial kit to label antibodies, care must be taken not to lose the activity of the antibody.

Common types of labels

  • Fluorescent labelling
  • Enzyme labelling
  • Biotin
  • Magnetic beads, agarose beads, magnetic agarose beads
  • Colloidal gold

Fluorescent labelling

Fluorescent labeled antibodies are used for flow cytometry and immunofluorescence staining. Multpile antibodies with different fluorescent labels can be used for double or triple staining.

Common fluorphores

Types of Fluorophore  
Fluorescent dye
(Low molecular weight fluorescent dye)
FITC (fluorescein isothiocyanate), Alexa Fluor®, Cy dyes, etc.
Fluorescent protein PE (phycoerythrin), APC (allophycocyanin), etc

Application example of fluorescent-labeled antibody: Immunofluorescence staining

Immunofluorescence staining with an antibody to an organelle marker.

HeLa cells were stained with an antibody to the Golgi protein GM130.

Direct-labeled antibody: Anti-GM130 mAb-Alexa Fluor® 488 (Code No. M179-A48)

Application example of fluorescent-labeled antibody: Flow cytometry

T cells are separated by type using fluorescent-labeled antibodies to cell surface markers.

T cells are separated into helper T cells, cytotoxic T cells, etc., by flow cytometry using antibodies labeled with different fluorophores (CD4-FITC, CD8-PE).

PE-labeled anti-CD8 antibody (Clone: KT15, Code No. D271-5)
FITC-labeled anti-CD4 antibody (Clone: GK1.5, Code No. D341-4)

Enzyme labelling

Enzyme-labeled antibodies are used for ELISA, Western blotting, and immunostaining. Labeled antibodies are detected by reaction with a substrate that emits light or changes color.

Commonly used enzyme

Enzyme Name Chromogenic Substrate Chemiluminescence Substrate
HRP (Horserashis peroxidase) DAB and TMB Luminol-based (ECL)
AP BCIP/NBT and pPNPP Dioxetane-based (CDP-star®)

Application example of enzyme-labeled antibodies: Immunohistochemical staining

The result of immunohistochemical staining indicates that autophagy was induced in the liver tissue.

  • Primary antibody: Anti-LC3 polyclonal antibody (Code No. PM036)
  • Secondary antibody: Histostar™ (Rb) for Human tissue (Peroxisdase-labeled, Code No. 8466)
  • Substrate: DAB Substrate Solution (Histostar™) (Code No. 8469)

Application example of enzyme-labeled antibodies: Western blotting

  • Primary antibody: Mouse anti-GFP antibody (Clone: 1E4, Code No. M048-3)
  • Secondary antibody: Anti-mouse IgG antibody (HRP-labeled, Code No. 330 (Only in Asia))


Biotin-labeled antibodies are used in flow cytometry, immunofluorescence staining, and immunohistochemical staining. Biotin-labeled antibodies are detected by reaction with dye-, enzyme-, or fluorophore-labeled avidin.

Antibody: Biotin-labeled anti-GP2 (Glycoprotein 2) antibody (Code No. D278-6)

Agarose, magnetic beads, magnetic agarose beads

Antibody-conjugated resins, such as magnetic beads and agarose, are used for immunoprecipitation.

  • The principle and method of immunoprecipitation (IP)

Colloidal gold

Gold-labeled antibodies are used in immunoelectron microscopy. This method is highly sensitive, and the signal does not fade as in fluorescent-labeling and enzyme-labeling.

Immunofluorescence staining with an antibody to an organelle marker.

  • Primary antibody: Anti-LC3 monoclonal antibody (Clone: 4E12, Code No. M152-3)

Related Links


Antibody basics

Antibodies as a research tool

Qualitative and quantitative measurements of proteins using antibodies

Fractionation and purification of proteins