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Safer Ethidium Bromide Alternatives

Ultra-sensitive DNA Stains
Much more sensitive than EtBr and SYBR® Safe.
Safer than EtBr
Shown by Ames test and other tests to be non-mutagenic and non-cytotoxic.
Easy disposal
Passed environmental safety tests for disposal down the drain or in regular trash.
Application Flexibility
Use in either precast or post electrophoresis staining.
Compatible with cloning and sequencing.
Extremely stable
GelRed® & GelGreen® DNA stains are stable at room temperature for long-term storage.
Broad instrument compatibility
Use UV and EtBr settings for GelRed®.
Use UV or blue LED for GelGreen® with SYBR® settings.

Choose the Right Stain for Your Application

Product / MethodProcedureAdvantagesDisadvantagesRecommended for
DNA prestaining with GelRed® Prestain Plus 6X DNA Loading DyeGelRed® loading buffer is added directly to the DNA sample before loading• Fast & simple: one-step sample loading & DNA staining

• Less concentrated dye for safer handling

• Can re-run a gel to use empty lanes
• Not recommended for PAGE, DGGE, EMSA, or PFGE gels

• Dye may cause band migration issues when loading larger amounts of DNA (more than ~100 ng/band), or for some restriction digests
• Routine agarose gels

• Recommended loading 50-200 ng ladder or 2-5 uL PCR product ( ~100 ng/band or less)
Precast staining with GelRed® 10,000X in water or GelGreen® 10,000X in water

GelRed® or GelGreen® is mixed with molten agarose before gel castingFamiliar protocol, rapid results
Precast staining with GelRed® Agarose LE or GelGreen® Agarose LE
Agarose is supplied pre-coated with GelRed® or GelGreen®, just dissolve, heat, and pourSafer & more convenient, no need to handle concentrated dye
Post-electrophoresis staining with GelRed® 10,000X in water or GelGreen® 10,000X in water
– or –
GelRed® 3X in water
No fluorescent dye is added to the gel, it is stained in 3X GelRed® or 3X GelGreen® solution after electrophoresis• Most accurate sizing/sharpest bands

• Staining solution can be re-used

• Enhance sensitivity by adding NaCl
Extra staining step (up to 30 minutes) after electrophoresis (some customers report good results after only 5 minutes if dye is not reused)• Highly accurate band sizing

• Gels with more than ~100 ng DNA per band

• Analyzing restriction digests
Post-electrophoresis staining of PAGE gels using PAGE GelRed® 10,000X or 1X in waterNo fluorescent dye is added to the gel, it is stained in 1X PAGE GelRed® solution after electrophoresis• Formulated for efficient penetration and staining of polyacrylamide gels

• Like the classic GelRed®, it is safe and environmentally friendly
Extra staining step of approx. 30 minutes after electrophoresisStaining of nucleic acids in PAGE gels

How Safe is Your Gel Stain?

A number of ethidium bromide (EtBr) alternatives are marketed as being safe. In fact, many so-called “safe” gel stains contain dyes that are well known to bind DNA in living cells, with cytotoxic effects. GelRed® and GelGreen® are highly sensitive gel stains designed to be non-toxic and non-mutagenic by virtue of being cell membrane-impermeant, so they cannot enter living cells. Download our white paper to learn more.

Safer alternatives to EtBr, SYBR® Safe, and others

EtBr has been the predominant dye used for nucleic acid staining for decades because of its low price and generally sufficient sensitivity. However, EtBr is a highly mutagenic material. The safety hazard and costs associated with decontamination and waste disposal can ultimately make the nucleic acid dye expensive to use. For this reason, various ethidium bromide alternative DNA gel stains have become commercially available in recent years. Although these alternative nucleic acid staining dyes are marketed as having low mutagenicity, they often have to sacrifice other aspects of the dyes. For example, SYBR® Safe has very limited sensitivity while SYBR® Green and SYBR® Gold are much less stable than EtBr. In addition, many so-called “safe” DNA dyes like Midori Green, GreenSafe, SafeView™, and RedSafe™ not only have low sensitivity, but also readily penetrate living cells to bind DNA, and some are cytotoxic. See our Gel Stains Comparison for details.

GelRed® & GelGreen® do not readily penetrate cells. HeLa cells were incubated for 30 minutes at 37°C with 1X SYBR® Safe, GelRed®, or GelGreen®. SYBR® Safe rapidly bound to DNA in live cells resulting in bright green nuclear staining. GelRed® and GelGreen® were unable to bind DNA in live cells, shown by the absence of fluorescence.

Non-toxic, non-mutagenic, and non-hazardous for disposal

To make GelRed® and GelGreen® safe, scientists at Biotium used a novel yet very simple concept: reduce genotoxicity by preventing the dyes from entering living cells. We believe that a DNA-binding dye can be made non-mutagenic or substantially so by denying its chance to be in contact with genomic DNA in living cells. Thus, we engineered the chemical structures of GelRed® and GelGreen® such that the dyes are incapable of crossing cell membranes. The Ames test confirmed that GelRed® and GelGreen® are non-mutagenic at concentrations well above their working concentrations used for gel staining. Furthermore, environmental safety tests showed that GelRed® and GelGreen® are nonhazardous and non-toxic to aquatic life. As a result, GelRed® and GelGreen® can be disposed of down the drain or thrown away in the regular trash. For more information, please download the GelRed® and GelGreen® Safety Report.

Comparison of mutagenicity among GelGreen®, GelRed®, SYBR® Green I and EtBr in +1 frameshift Salmonella indicator strain TA98 with the presence of S9 fraction. * indicates EB was not tested at this concentration. # indicates SYBR Green I was toxic at this concentration.

Superior sensitivity and flexible applications

GelRed® and GelGreen® are highly sensitive either as precast gel stains or post gel stains. GelRed® is much more sensitive than EtBr, and unlike SYBR® Gold, GelRed® can also be used as a highly sensitive precast gel stain. GelRed® is also available as a convenient prestain loading buffer. GelGreen® is spectrally similar to SYBR® Safe but is far more sensitive, and can be used with blue light gel imaging systems like the DarkReader®. PAGE GelRed® is designed for staining DNA in acrylamide gels. Another major advantage of GelRed® and GelGreen® DNA stain is their remarkable stability. You can store and handle the two nucleic acid staining dyes the same way you do with EtBr. For convenience, GelRed® and GelGreen® are also available in pre-coated agarose formats. For detailed protocols for use of the DNA stains, please download the GelRed® Product Information Sheet or GelGreen® Product Information Sheet.


  • More sensitive than EtBr, SYBR® Safe, and others
  • Use in precast or post-stain
  • Compatible with downstream cloning and sequencing
  • GelRed® available in 6X loading buffer format
  • PAGE GelRed® for acrylamide gels
  • GelRed®: use UV transilluminator and EtBr filter
  • GelGreen®: Use UV or blue LED and SYBR® filter, or our new Gel-Bright™ Laser Diode Gel Illuminator

GelRed® Is Superior to EtBr

Comparison of ethidium bromide (EtBr) and GelRed® in precast gel staining using 1% agarose gel in TBE buffer. Two-fold serial dilutions of 1 kb Plus DNA Ladder (Invitrogen) were loaded in the amounts of 200 ng, 100 ng, 50 ng and 25 ng from left to right. Gels were imaged using 300 nm transilluminator and photographed with an EtBr filter.

GelGreen® Is Unmatched by SYBR® Safe

Comparison of GelGreen® and SYBR Safe in post-electrophoresis staining of 1% agarose/TBE gels. Two-fold serial dilutions (200 ng, 100 ng, 50 ng and 25 ng) of 1 kb Plus DNA Ladder (Invitrogen). Gels were imaged using 254-nm UV transilluminator and photographed with a SYBR filter.

Excitation and emission spectra of GelRed® and GelGreen® with DNA.

Click here to download an App Note on using GelRed® and GelGreen® on the UVP GelDoc-It® imaging system.

Click here to download an App Note on using GelGreen® on the UVP GelDoc-It® imaging system with the Visi-Blue™ Converter Plate.

Product NameCatalog NumberSize
GelRed® 10,000X in water41003-T0.1 mL (Trial Size)
410030.5 mL
41003-110 mL
GelGreen® 10,000X in water410050.5 mL
41005-110 mL
GelRed® 3X in water410014 L
6X GelRed® Prestain Loading Buffer, Orange Tracking Dye410101 mL
GelRed® Prestain Plus 6X DNA Loading Dye410111 mL
GelRed® Agarose LE41029-5G5 g
41029-50G50 g
GelGreen® Agarose LE41030-5G5 g
41030-50G50 g

GelGreen® Nucleic Acid Gel Stain

From: $29 Sizes: Trial size (0.1 mL), 0.5 mL, 10 mLCatalog #:
, 41005, 41005-1, - 41005-TView allHide

GelRed® Nucleic Acid Gel Stain

From: $33 Sizes: Trial size (0.1 mL), 0.5 mL, 10 mL, 4 LCatalog #:
, 41002, 41003, 41002-1, 41003-1, - 41003-TView allHide

GelRed® Agarose LE

From: $61 Sizes: 5 g, 50 gCatalog #:
, - 41029-50GView allHide

GelGreen® Agarose LE

From: $59 Sizes: 5 g, 50 gCatalog #:
, - 41030-50GView allHide

GelRed® Prestain Plus 6X DNA Loading Dye

From: $106 Sizes: 1 mLCatalog #: 41011


GelRed® and GelGreen® Troubleshooting

Many customers use GelRed® or GelGreen® precast gels for convenience. However, because GelRed® and GelGreen® are high affinity dyes designed to be larger dyes to improve their safety, they can affect the migration of DNA in precast gels. Some samples, such as restriction digested DNA may migrate abnormally in GelRed® or GelGreen® precast gels. Tip #1: Load less DNA Smearing and smiling in GelRed® or GelGreen® precast gels most often caused by overloading of DNA. If you see band migration shifts or smearing and smiling, try reducing the amount of DNA loaded. The recommended loading amount for ladders and samples of known concentration is 50-200 ng/lane. For samples of unknown concentration, try loading one half or one third of the usual amount of DNA. This usually solves band migration problems. Tip #2: Try the post-staining protocol To avoid any interference the dye may have on DNA migration, we recommend using the post-staining protocol. If your application requires loading more than the recommended amount of DNA, use the post-staining protocol. While we recommend post-staining gels for 30 minutes, you may be able see bands in as little as five minutes, depending on how much DNA is present. Post-staining solutions can be reused. See the GelRed® Product Information Sheet or GelGreen® Product Information Sheet for detailed protocols. Other tips to improve agarose gel resolution:
  • If you see DNA migration issues or smearing after post-staining with GelRed® or GelGreen®, then the problem is not caused by the nucleic acid dye. Avoid overfilling gel wells to prevent smearing of DNA down the surface of the gel.
  • Pour a lower percentage agarose gel. Higher molecular weight DNA separates better with a lower percentage gel.
  • Change the running buffer. TBE buffer has a higher buffering capacity than TAE buffer.

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There are a few possibilities:
  1. The dye may have precipitated out of solution.
    • Heat the GelRed® or GelGreen® solution to 45-50°C for two minutes and vortex to dissolve.
    • Store dye at room temperature to avoid precipitation.
  2. If you are seeing high background staining of the gel, the agarose that you are using may be of low quality. Contaminants in the agarose may bind to the dye, resulting in increased background.

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GelRed® and GelGreen® Nucleic Acid Gel Stains

Most of our products are stable at room temperature for many days, so in all likelihood the product will still work just fine. To be on the safe side, we recommend performing a small scale positive control experiment to confirm that the product still works for your application before processing a large number of samples or precious samples. One exception that we are aware of is GelGreen™, which is more sensitive to light exposure than most of our other fluorescent dyes. If GelGreen™ is exposed to ambient light for a prolonged period of time (days to weeks), its color will change from dark orange to brick red. If this occurs, the GelGreen will no longer work for gel staining.  

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The main difference between GelRed® and GelGreen® is their fluorescence excitation and emission wavelengths. GelRed® has red fluorescence, similar to ethidium bromide. GelGreen® has green fluorescence, similar to SYBR® Green or SYBR® Safe. Both dyes are compatible with standard UV transilluminators. GelGreen® is also compatible with blue light transilluminators, which allow users to avoid exposing themselves and their DNA samples to ultraviolet radiation. GelRed® and GelGreen® have higher sensitivity for double stranded nucleic acids compared to single stranded nucleic acids, but GelRed® is more sensitive for staining single stranded nucleic acids than GelGreen®. GelRed® is about twice as sensitive for double stranded nucleic acids compared to single-stranded nucleic acids, and about five times more sensitive than GelGreen® for staining single stranded nucleic acids. For more information about these products, please visit our DNA stains technology page.

View the GelRed® Product Line

View the GelGreen® Product Line

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The water formulation is a newer and improved product compared to the stock in DMSO. We recommend using dyes in water to avoid the potential hazards of handling DMSO, which can be absorbed through the skin. We continue to offer dyes in DMSO because some users do not wish to alter their established laboratory protocols. Based on internal testing, both formulations perform similarly.

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