|Dye||Abs (nm)||Em (nm)||ε (M−1cm−1)||QY|
|Abs = absorption maximum#, Em = emission maximum#,
ε = molar extinction coefficient, QY = fluorescence Quantum Yield#
# in water
ATTO Dyes are a series of fluorescent labels and dyes manufactured by ATTO-TEC GmbH in Siegen, Germany. The dyes have been designed for application in the area of life science, e.g. labeling of DNA, RNA and proteins as well as analytical applications, in particular fluorescence microscopy.
The ATTO Dye series covers a spectral range from 390 nm in the UV up to 740 nm in the near infrared allowing excitation with most commonly used light sources. The dyes typically are derivatives of coumarins, rhodamines, carbopyronins and oxazines. They are commercially available as free carboxylic acids, amine reactive N-hydroxy-succinimidyl-esters (NHS-ester) or thiol reactive maleimides.
Many common fluorescent labels, e.g. Fluorescein (FITC), show rather low photostability. As a result sensitivity and quality of imaging are limited if high-intensity laser excitation is used and processes are to be observed over long periods of time. This is a serious draw-back in microscopy and other techniques based on the confocal principle, e.g. in single-cell detection applications. In contrast to some widely used older dyes, the patented ATTO-labels are designed to be much more stable under prolonged irradiation.
In addition many common fluorescent labels especially cyanine dyes like Cy5 deteriorate even without any irradiation (in the dark), in particular when exposed to small concentrations of ozone present in the laboratory atmosphere. Under identical conditions of ozone exposure the new dyes ATTO 633, ATTO 647N and ATTO 655 last up to 100 times longer than cyanines like Cy5 and Alexa Fluor 647. This is very important in microarray applications, where the dye molecules are located at the surface and thus are in direct contact with the atmosphere.