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ExoBrite™ CD81 Western Antibody

Validated antibody for optimal detection of exosome marker CD81 in extracellular vesicle (EV) extracts by fluorescent western blot.

Product Attributes

Antibody number




Antibody type




Host species



IgG1, kappa

Antibody reactivity (target)



CD81; Target of the antiproliferative antibody 1 (TAPA-1); Tetraspanin-28; Tspan-28

Species reactivity

Baboon, Cynomolgus monkey, Human, Non-human primates

Human gene symbol


Entrez gene ID




Molecular weight

26 kDa

Antibody target cellular localization

Exosomes/EVs, Plasma membrane

Cell/tissue expression

Exosomes, Hepatocytes, Lymphocytes, Monocytes/macrophages

Verified antibody applications

WB (verified)

Shipping condition

Room temperature

Positive control

MCF-7 cells, MCF-7 derived exosomes

Antibody application notes

Recommended amount for western blot: 10 uL per 10 mL blocking buffer

Antibody research areas


Antibody/conjugate formulation

PBS, 0.1% BSA, 0.05% azide

Shelf life

Guaranteed for at least 24 months from date of receipt when stored as recommended

Storage Conditions

Store at 2 to 8 °C, Protect fluorescent conjugates from light

Regulatory status

For research use only (RUO)

Catalog #
25 tests
100 tests
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Product Description

ExoBrite™ CD81 Western Antibody is validated by Biotium for optimal detection of exosome marker CD81 in extracellular vesicle (EV) extracts by fluorescent western blot. The antibody is offered as a conjugate to either ExoBrite™ 680/700 or ExoBrite™ 770/800 near-infrared fluorescent dyes, which offer greater signal-to-noise than visible light fluorescent dyes for western blotting.

  • Optimal detection of exosome marker CD81 by fluorescent western blot
  • Validated for use with EV extracts
  • Bright signal and low background
  • Available in 2 near-infrared colors

EVs, including exosomes, are lipid-bound vesicles that are released from cells. EVs display specific surface proteins and can carry nucleic acids and other cargo, allowing them to transfer biological information between cells in different parts of the body. Therefore exosomes are increasingly studied for their potential use in drug delivery and medical diagnostic applications. The most common proteins used as exosome markers are CD9, CD63, and CD81, members of the tetraspanin family. Tetraspanins are plasma membrane proteins with many proposed functions, including activation and sorting of other membrane proteins. They are also thought to play a role in the targeting of proteins to multivesicular bodies (MVBs) and exosomes. These tetraspanins are broadly expressed on many cell types and can therefore be detected on many types of exosomes, but their expression levels vary depending on the cell type of origin.

Exosome antibodies you can trust

Other commercially available antibodies for tetraspanin proteins CD9, CD63, and CD81 are generally not validated for isolated exosomes and may require tedious optimization for your exosome prep and staining protocol. ExoBrite™ Western Antibody Conjugates were validated to offer bright signal and low background of exosome markers in EV extracts. ExoBrite™ Calnexin Western Antibody detects a protein of the endoplasmic reticulum that is not found in exosomes. It is offered as a negative control to assess the purity of isolated exosome extracts.

Biotium also offers ExoBrite™ EV Membrane Staining Kits and a ExoBrite™ CD81 Flow Antibody for detection of isolated EVs and exosomes by flow cytometry. ExoBrite™ EV Membrane Staining Kits may also be combined with antibody staining, for multi-parameter analysis.

ExoBrite™ Western Antibody Conjugates

Antibody Ex/Em Size Catalog No.
ExoBrite™ 680/700
CD9 Western Antibody
681/698 nm 25 tests P003-680-250
100 tests P003-680-1000
ExoBrite™ 770/800
CD9 Western Antibody
770/797 nm 25 tests P003-770-250
100 tests P003-770-1000
ExoBrite™ 680/700
CD63 Western Antibody
681/698 nm 25 tests P004-680-250
100 tests P004-680-1000
ExoBrite™ 770/800
CD63 Western Antibody
770/797 nm 25 tests P004-770-250
100 tests P004-770-1000
ExoBrite™ 680/700
CD81 Western Antibody
681/698 nm 25 tests P006-680-250
100 tests P006-680-1000
ExoBrite™ 770/800
CD81 Western Antibody
770/797 nm 25 tests P006-770-250
100 tests P006-770-1000
ExoBrite™ 770/800
Calnexin Western Antibody
770/797 nm 25 tests P007-770-250
100 tests P007-770-1000

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