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Ethidium Monoazide, Bromide (EMA)

Ethidium monoazide bromide is a fluorescent nucleic acid binding dye. The dye, after photolysis, binds covalently to nucleic acids. It can be used for viability PCR.

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Product Description

Ethidium monoazide bromide (EMA) is a fluorescent nucleic acid stain with a photoaffinity label. The dye, after photolysis, binds covalently to nucleic acids.The dye has been used to footprint drug binding sites on DNA2, to modify plasmid DNA,3,4 and for labeling yeast cells for leukocyte phagocytosis assays5. A particularly useful application of the dye is to label dead cells in a mixed population of live and dead cells. Because EMA is relatively impermeant to live cells, it selectively binds DNA in dead cells. Photolysis renders the dead cell DNA covalently labeled with the dye. One can then wash and fix the cell preparation for analysis by microscopy, fluorescence plate reader or flow cytometry. The major advantage of this method is that researchers can avoid extensive manipulation of live pathogenic organisms.7

EMA has been used to differentiate between viable and dead bacteria by 5′-nuclease PCR.8

For viability PCR applications, Biotium also offers propidium monoazide iodide (PMA, catalog numbers 40013 and 40019) as well as our new and improved viability PCR dye, PMAxx™ (catalog number 40069). PMA and PMAxx™ are less membrane permeant than EMA and therefore more selective for dead cell labeling for qPCR quantitation of viable bacteria.9

For photoactivation of PMA, PMAxx™ or EMA dye, we recommend the use of Biotium’s PMA-Lite™ LED Photolysis Device (E90002), which is designed to conduct photolysis under controlled conditions.

    • Ex (pH 3) = 458 nm
    • λExEm (after photocrosslinking to nucleic acid) = 510/600 nm6

    • Orange solid soluble in DMF, or ethanol
    • Store desiccated at 4oC or -20oC and protect from light, especially in solution
    • C21H18BrN5
    • MW: 420
    • [58880-05-0]



1. J Mol Biol 92, 319 (1975).

2. Euro J Biochem 182, 437 (1989).

3. J Biol Chem 257, 13205 (1982).

4. J Biol Chem 259, 11090 (1984);.

5. Cytometry 11, 610 (1990).

6. For excitation and emission of the dye before and after binding to DNA/RNA and photolysis, please see Nucleic Acids Res.5, 4891 (1978).

7. Cytometry, 12, 133 (1991).

8. Biotechniques, 34, 804 (2003)

9. J. Microb. Meth., 67, 310 (2006).


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PMA and PMAxx™ for viability PCR

Viability PCR originally used EMA (ethidium monoazide) to inactivate dead cell DNA. Biotium developed PMA (propidium monoazide) in collaboration with investigators at Montana State University (Nocker et al. 2006). PMA is more selective for dead cells than EMA, and became widely used for selective detection of viable microbes and viruses. PMAxx™ is Biotium’s newest viability PCR dye, designed to be more effective than PMA at eliminating PCR amplification of dead cell DNA. Therefore it provides the best discrimination between live and dead bacteria.

Learn more about PMA and PMAxx™ for viability PCR.

Category: PMA and PMAxx™ for viability PCR

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Biotium offers the PMA-Lite™ LED Photolysis Device for light-induced cross-linking of PMAxx™ and PMA to dsDNA. The PMA-Lite™ is designed for samples in microcentrifuge tubes. We also offer the Glo-Plate™ Blue LED Illuminator for photoactivation of larger tubes, 96-well plates, or other plate formats.

Commercial halogen lamps (>600 W) for home use have been employed for photoactivating PMA in some publications, though results have not been consistent due to inevitable variation in the set-up configurations. If you decide to use a halogen lamp, we recommend that you lay tubes on a block of ice set 20 cm from the light source, on a rocking platform to ensure continuous mixing. Set the lamp so that the light source is pointing directly downward onto the samples (up to 45° downward slant is OK). Expose samples to light for 5-15 min.

Category: PMA and PMAxx™ for viability PCR

← FAQs

The LEDs in PMA-Lite have brightness of 600-800 millicandela (mcd). There are three LEDs next to each tube (one bottom, two side) and the wavelength is 465-475 nm.

Category: PMA and PMAxx™ for viability PCR

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Shipping & Handling Disclaimer: Shipping and handling methods are calculated based on item temperature storage recommendation. Large, multi-item orders may be assessed additional fees. Shipping to Puerto Rico may be assessed additional fees. A Biotium customer service representative will contact you if additional fees are required. For expedited shipping, please request in the Order Notes section of the checkout page. Please note that products with recommended storage at 4°C or -20°C may ship at ambient temperature. This will not affect product performance. When you receive the product, place it under the recommended storage conditions.