SYBR Safe is a cyanine dye[1] used as a nucleic acid stain in molecular biology.

Here, the synthesis of these compounds are published and characterised spectroscopically to quantify their fluorescence enhancement upon binding to double-stranded DNA.

[3] SYBR Safe is marketed as a safer alternative to ethidium bromide.

[4] SYBR Safe has a very similar structure to thiazole orange,[5][6][7] which has a methyl group attached to the charged nitrogen, whereas SYBR Safe has an N-propyl group.

[8] Additionally, according to the Life Technologies website, SYBR Safe is not lethal in rats at doses as high as 5 g/kg, and rats don't show symptoms of acute toxicity.