May 7, 2024

Biotium Launches Novel Membrane Dyes Designed for Superior Pan-EV Labeling Over PKH and Other Membrane Dyes

By: Kyrie Sismaet

New ExoBrite™ True EV Membrane Stains offer strong signal and near-complete staining of extracellular vesicles.

Fremont, CA, May 7, 2024: Biotium, a leading supplier and inventor of fluorescent cellular probes for life science research, announces the release of ExoBrite™ True EV Membrane Stains for detection of extracellular vesicles (EVs). ExoBrite™ True EV Membrane Stains are novel membrane dyes designed for clear differentiation of EVs from non-specific particles during flow detection. Fluorescence nanoparticle tracking analysis (fNTA) determined the stains to be a superior choice over PKH with higher (near-complete) pan-EV staining. ExoBrite™ True EV Membrane Stains are offered in two colors for detection in FITC or PE channels, and can be used with antibodies for multi-parameter analysis. The stains are also available in a standard size of 500 labelings, or trial size of 100 labelings. To learn more about ExoBrite™ True EV Membrane Stains, visit the product page.

Flow cytometry and fNTA analysis of SEC purified MCF-7-derived EVs stained with ExoBrite™ 515/540 True EV Membrane Stain and PKH67. Left: Analysis on a CytoFLEX LX flow cytometer shows ExoBrite™ True EV Membrane Stain was able to differentiate EVs from background particles, unlike PKH67. Stained EVs were detected in the FITC channel. Right: In ZetaView^® fNTA, ExoBrite™ 515/540 True EV Membrane Stain showed nearly complete coverage of EVs, much higher than PKH67. Total EV number was measured in scatter mode, and fluorescently-stained EV number was measured with 488 nm excitation and 500 nm filter. The percentage of particles stained with the dye is shown in the plot.

“We are very excited about the new ExoBrite™ True EV Membrane Stains” says Dr. Alexis Madrid, head of Biotium’s EV product development group. “We know that many researchers want good, clean pan-EV stains and EV membrane stains, and for years many people have struggled to get good results staining EVs with other membrane dyes. Now scientists at Biotium have invented a set of membrane dyes that are specifically designed for EVs. These dyes will allow researchers to confidently stain their EVs and achieve greater coverage and cleaner results than ever before.”

Features of ExoBrite™ True EV Membrane Stains:

Lipophilic membrane dyes designed for pan-EV labeling
Superior alternative to common membrane dyes like PKH, DiO, DiI, DiD
Near-complete coverage of EVs in a sample
Broad compatibility with EVs isolated from different sources
Compatible with antibody-co-staining

After realizing an unmet need for reliable probes for EV detection, particularly in flow cytometry, Biotium sought to launch a diverse line of unique reagents aimed at addressing these challenges, beginning with the 2021 release of ExoBrite™ CTB EV Staining Kits (formerly ExoBrite™ EV Membrane Staining Kits). 2022 saw the introduction of the ExoBrite™ Antibody Conjugates (CD9, CD63, and CD81) for flow cytometry and western blotting, followed by ExoBrite™ WGA (wheat germ agglutinin conjugates) and Annexin V EV Surface Stains. An ExoBrite™ EV Surface Stain Sampler Kit that includes samples of ExoBrite™ CTB, WGA, and Annexin V stains is also now available, as well as ExoBrite™ Streptavidin Magnetic Beads that can be combined with biotinylated antibodies for efficient EV capture and isolation.

Sensitive and specific reagents for labeling EVs for detection by flow cytometry and other applications continues to be a strong pursuit for Biotium, and ExoBrite™ True EV Membrane Stains further adds to their versatile repertoire of robust reagents for EV research.

CytoFLEX is a registered trademark of Beckman Coulter, Inc. ZetaView is a registered trademark of Particle Metrix.