SYBR Safe

SYBR Safe is a cyanine dye used as a nucleic acid stain in molecular biology. SYBR Safe is one of a number of SYBR dyes made by the Life Technologies Corporation. SYBR Safe binds to DNA. The resulting DNA-dye-complex absorbs blue light (λmax = 509 nm) and emits green light (λmax = 524 nm).

A comprehensive Study of Thiazole-Orange-Based DNA Dyes were published, involving SYBR Safe, SYBR Green, PicoGreen, SYTO-16, SYTO-9 and a new derivative TOPhBu. Here, the synthesis of these compounds are published and characterised spectro-scopically to quantify their fluorescence enhancement upon binding to double-stranded DNA. The ability of the dyes to detect DNA at low concentrations was evaluated using two new metrics, absolute fluorescence enhancement (AFE) and relativefluorescence enhancement (RFE). They were tested in qPCR experiments showing some important differences in the sensitivity and qPCR efficiency, which facilitate the DNA marker selection for analytical purposes.

Safety
SYBR Safe is marketed as a safer alternative to ethidium bromide. However, as the molecule itself is quite a bit larger than ethidium bromide, it does not bind to the column of a gel extraction as easily, making it less efficient when trying to clone a DNA fragment into a plasmid. SYBR Safe has a very similar structure to thiazole orange,  which has a methyl group attached to the charged nitrogen, whereas SYBR Safe has an N-propyl group. Thiazole Orange has been shown to be three to four times less mutagenic than ethidium bromide whereas SYBR Safe is four to five times less mutagenic. 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. Thiazole orange does show toxicity at this dose.

Similar cyanine dyes

 * TO (Thiazole Orange)
 * SYBR Green I
 * SYBR Green II
 * SYBR Gold
 * YO (Oxazole Yellow)
 * PG (PicoGreen)