Biotium introduces new line of antibodies for exosome detection

Figure 1. EC-purified MCF-7-derived exosomes were stained with ExoBrite™ CD9 560/585 Flow Antibody (left). Specific staining was seen, compared with the same antibody in buffer (right). Exosomes were detected on a CytoFLEX LX flow cytometer in the PE channel. 

Biotium, a leading supplier and inventor of fluorescent cellular probes for life science research, announces the release of new ExoBrite™ Antibody Conjugates. These antibodies were curated specifically for optimal detection of exosome markers CD9, CD63, and CD81 in isolated exosomes or exosome extracts with little to no background. ExoBrite™ Antibody Conjugates are available in formulations for both flow cytometry and western blotting. 

Extracellular vesicles (EVs), including exosomes, are increasingly studied for their roles in cell communication, and as potential targets for diagnostic and drug delivery applications. The most common proteins used as exosome markers are CD9, CD63, and CD81, members of the tetraspanin family. While antibodies targeting these proteins are available by commercial suppliers, few are validated or perform well for detection of EVs or exosomes. ExoBrite™ Flow Antibody Conjugates and ExoBrite™ Western Antibody Conjugates were developed by Biotium scientists for optimal detection of CD9, CD63, and CD81 exosome markers for flow cytometry and western blotting.

ExoBrite™ Flow Antibodies are designed for detection of isolated or bead-bound EVs by flow cytometry. The antibodies are available in 4 conjugates: ExoBrite™ 410/450 (Pacific Blue™ channel), ExoBrite™ 490/515 (FITC channel), ExoBrite™ 560/585 (PE channel with yellow laser), and ExoBrite™ R-PE (PE channel). Isotype controls are also available for each conjugate.

ExoBrite™ Western Antibodies are designed for detection of exosome markers in EV extracts by near-IR fluorescent western blot. The antibodies are available with two near-infrared fluorescent dyes, ExoBrite™ 680/700 and ExoBrite™ 770/800, which offer greater signal-to-noise for western blotting than dyes with visible light emission. An ExoBrite™ Western Antibody for detection of calnexin, a membrane protein localized in the endoplasmic reticulum that is not found in exosomes, is also available as a negative control for assessing purity of exosome extracts. 

Figure 2. Western detection using ExoBrite™ Western Antibodies and MCF-7 cell and exosome lysates, showing tetraspanin protein enrichment and calnexin depletion in exosomes. Blots were stained with ExoBrite™ 770/800 Calnexin Antibody (exosome negative control) plus (A) ExoBrite™ 680/700 CD9 Antibody, (B) ExoBrite™ 680/700 CD63 Antibody, or (C) ExoBrite™ 680/700 CD81 Antibody. Lane M: Protein marker. Lane 1: 10 ug cell lysate. Lane 2: 1 ug cell lysate. Lane 3: 1 ug exosome lysate. The blots were imaged on a LI-COR Odyssey® infrared imaging system.

The release of ExoBrite™ Antibody Conjugates add to Biotium’s growing line of optimized solutions for exosome and EV research. Biotium also offers ExoBrite™ EV Membrane Staining Kits which are designed for bright and specific staining of isolated EVs with little to no background. ExoBrite™ EV Membrane Staining Kits are available with four color options for the Pacific Blue™, FITC, PE, and APC channels. Learn more about Biotium’s novel solutions for EV research.

About Biotium

Biotium is a leading life science reagent manufacturer and supplier devoted to providing high-quality and innovative fluorescent tools that fuel scientific discovery. Our collaborative team of experienced chemists and biologists, who are at the forefront of fluorescent dye design, apply chemistry-based principles toward producing solutions for unmet challenges in life science and medical research. Since its founding in 2001, Biotium has developed over 30 patented technologies that have been licensed out to leading life science technology companies worldwide. For more information, please visit www.biotium.com.