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Oxazole Yellow (YO-PRO®-1), 1 mM in DMSO

Oxazole yellow, also known as YO-PRO®-1, is a green-fluorescent, cell-impermeant nucleic acid stain that can be used as a early marker of apoptosis.

Product Attributes

Cellular localization

Nucleus & cytoplasm

Assay type/options

No-wash staining, Real-time imaging

Cell permeability

Membrane impermeant




491/509 nm (with DNA)

Note: Due to operating restrictions related to our COVID-19 response, primary antibody conjugates of R-PE, APC, PerCP, HRP, or AP are temporarily unavailable. All other antibody options are still available. We apologize for the inconvenience. Please see our easy-to-use Mix-n-Stain™ Antibody Labeling Kits for labeling antibodies with R-PE, APC, tandem dyes, and enzymes.
Catalog #
1 mL
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Product Description

Oxazole yellow, also known as YO-PRO®-1, is a green-fluorescent, cell-impermeant, high-affinity carbocyanine monomeric nucleic acid stain.

  • Monomeric nucleic acid stain
  • Cell-impermeant
  • Early marker of apoptosis
  • λExEm (with DNA) = 491/509 nm
  • Supplied at 1 mM in DMSO

It is essentially non-fluorescent in the absence of nucleic acids but exhibits excitation/emission maxima 491/509 nm when bound to nucleic acids. Oxazole yellow is also used to identify apoptotic cells. Early apoptotic cells become permeant to oxazole yellow, but remain impermeant to propidium iodide (cat. no. 40016), a dead cell stain.


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