I´ve already used both of them. EtBr is simple and don´t require to much adjust, but is very toxic and carcinogenic, even in low concentrations. In the other hand, it may require a little more time to get the right amount of SYBR Safe to match your needs.

Nowadays, I use GEL RED (20X concentrated) in my PCR samples. Briefly, 1 uL of Gel Red 20X to 19 uL of PCR product.

EtBr will enable the visualization of smaller quantities of DNA from my experience, and can distinguish between 2 bands of very similar sizes without "merging" into one (genotyping mice etc). EtBr is very toxic but begins to break down at approximately 260 degrees centigrade according to data sheets I have read. i.e. Negligible vapour pressure at the Bpt of buffered water. If a non-toxic reagent substitute can be used then it should but EtBr does have its advantages.

EtBr is very toxic, but we can distinguish and differentiate 2 very small bands. If we want to use GEL RED and SYBR Safe , we should adjust right amount. I obtained suitable result by GEL RED, but it 's expensive.

Most of reagents with the label of "safe " had their behaviour based on their inability to defuse across cell membranes. This has been the basis of PI, PMA or EMA applications. Gel Red simply is a Ethidium homodimer form. Really all this reagents are very safe if are compared with EtBR, but as mots of them are derivatives forms from intercalating agents, despite their purity still remains al least a 2% of EtBR or other high mutagen forms. About Sybr safe, I don't know nothing because until I have read the chemical formule or CAS number not is public. Have you got this information? in this case maybe I coulb be more clear.

best regards

To bring the other side of the story, this blog http://rrresearch.fieldofscience.com/2006/10/heresy-about-ethidium-bromide.html talks about the use of EtBr in cattle with no adverse effects over a number of years. Please note thedosage was 1-50 mg/kg. Yes, those units are correct. I am afraid the rumours of the deadly toxicity of EtBr are many and exaggerated.

We have used both GR green and EtBr somehow we've had changed band sizes using anything other then EtBr. We weren't able to find any reproducible effects but regularly changes in sizes if we used GR green directly along with loading buffers - so we avoid procedure and use EtBr instead. Moreover it is questionable, if these replacements really are less mutagenic since a dye that intercalates in the DNA always causes mutations.. its just a matter of fact..

I work at Biotium Inc, the manufacturer of GelRed, and would like to address a previous comment that GelRed is contaminated with ethidium bromide (EtBr):

Gel Red simply is a Ethidium homodimer form. Really all this reagents are very safe if are compared with EtBR, but as most of them are derivatives forms from intercalating agents, despite their purity still remains al least a 2% of EtBR or other high mutagen forms.

It is not possible for GelRed to be contaminated with EtBr, because the dye is not made from EtBr, and EtBr is never produced at any point during GelRed synthesis. However, we are aware that there are infringers that claim that their products are GelRed, but in fact are something else. Therefore, we recommend for our customers to purchase GelRed directly from us, or from one of our authorized distributors (http://biotium.com/authorized-distributors/).

Testing by independent third-party laboratories has shown that GelRed at working concentrations is non-toxic, non-mutagenic, and non-hazardous to aquatic life. GelRed’s safety is attributed to its low cell membrane permeability. Even if some of the dye gets into cells at high dye concentrations, it does not stain the cell nucleus. In contrast, Ohta et al. showed that EtBr, SYBR Green, and acridine orange (dyes that readily stain the cell nucleus) interfere with DNA repair mechanisms in cells, which potentiates the genotoxicity of other chemicals as well as DNA damage by UV light (https://www.researchgate.net/publication/11961790_Ethidium_bromide_and_SYBR_Green_I_enhance_the_genotoxicity_of_UV-irradiation_and_chemical_mutagens_in_E._coli). In addition, it is worth noting that molecular analysis performed by Biotium chemists of several other dyes that are marketed as safe alternatives to EtBr revealed them to contain acridine orange or derivatives of acridine orange, one of the dyes shown by Ohta et al. to be genotoxic (you may contact us at [email protected] for more information, if desired).

http://biotium.com/authorized-distributors/

Article Ethidium bromide and SYBR Green I enhance the genotoxicity o...

Ive been using Gel Red successfully arounf 8 years ago in a different lab and wanted to start using it in my current lab but the DNA ladder always come as smeary.. the bands stack together (Im using 50ng/lane of MBI fermentas Gene Ruler 100bp plus and 1kb plus. Anyone have an idea how to solve it?   We use the gelRed in the precast gel and post staining is not possible for us.

Thanks

Hi Mily, I get stacking of large fragments (>9kb) when I use the precast method for GelRed. Smaller fragments are always fine though. The effect disappears when I post-stain, or if I mix GelRed with my loading dye. However the loading dye method really screws up the sizing as it affects gel migration. If you aren't too worried about sizing, you try it. It's also been suggested that I reduce the amount of ladder, though I haven't tried it yet.