ATTO and alternative dye

Activated fluorescent dyes have become the standard procedure for stable labelling of proteins, nucleic acids, ligands and other biomolecules, which are widely used for applications as fluorescence microscopy, flow cytometry, fluorescence in situ hybridization (FISH), receptor binding assays, or enzyme assays.  ATTO dyes are a series of fluorescent dyes which provide all the crucial properties required for modern fluorescent technologies with spectral region from 350 nm in the UV to 750 nm in the near infrared.

ATTO dyes main features are:

• Spectral Data:  Absorption maxima fit commonly used excitation sources (Table 1) and emission maxima cover a broad range from 500 to 700 nm.

• Stokes’ Shift: Shift between absorption maximums and emission maximum is sufficient to discriminate the fluorescence emission from scattered excitation light.
• Brightness: Bright fluorescence due to strong absorbance (molar extinction above 105) and high quantum yields (ranging from 0.3 to 0.9).
• Photostability: Structural properties support excellent photostability.
• Hydrophilicity: Good, supporting labelling in aqueous solutions.
• Reactivity: All dyes are available as activated NHS esters, matching most common labelling procedures for proteins and amino functionalized oligonucleotides. In addition, a series of thiol reactive maleimides are available.

ATTO-TEC labels also find many applications in fluorescence spectroscopy. All dyes are fully characterized and can be used in time resolved spectroscopy, FRET (Fluorescence Resonance Energy Transfer), Real-Time qPCR, assays applications, as well as single- molecule detection.

• ATTO 520 and ATTO 532 are fluorescent labels related to the well-known dye Rhodamine-6G.
• ATTO 550 is a fluorescent label related to the well-known dyes Rhodamine-6G and Rhodamine B, the commercial alternative to NEDTM.
• ATTO 565, ATTO 590 and ATTO 594 are fluorescent labels belonging to the class of Rhodamine dyes. ATTO 594 is an alternative to Alexa Fluor® 594. ATTO 594 exhibits excellent water solubility, very good stability over a wide pH range, very good photo-stability, and high fluorescence quantum yield.
• ATTO 610, ATTO 611X, ATTO 620, ATTO 633, ATTO 635, ATTO 637, ATTO 647 and ATTO 647N are fluorescent labels for the red spectral region.
• ATTO 633 is an alternative to Alexa Fluor 633. ATTO 633 shows strong absorption, very high fluorescence quantum yield, and very good stability in the pH-range 2 to 10.
• ATTO 637 is another alternative to Alexa Fluor 633. Although very similar to ATTO 635, ATTO 637 is more hydrophilic and more soluble in water.
• ATTO 647N is an alternative to Cy® 5 and Alexa Fluor® 647. The characteristic features of ATTO 647N are strong absorption, extraordinary high fluorescence quantum yield and outstanding pH and photo-stability.
• Suitable excitation sources for ATTO 637 are the 633 nm line of the He:Ne Laser or a Diode-Laser emitting at 635 nm. ATTO 647 and ATTO 647N are excited most efficiently in the range 615 - 660 nm. A suitable excitation source, for instance, is the 647 nm line of the Krypton-Ion laser or a Diode-Laser emitting at 650 nm.
• ATTO 655, ATTO 680 and ATTO 700 belong to a new generation of fluorescent labels. Their fluorescence is excited most efficiently in the range 625 - 660 nm, 645 - 695 695 nm and 665 – 715 nm, respectively. A suitable excitation source for these dyes is the Krypton-Ion laser, using the 757 nm line or a Diode-Laser emitting at 670 nm.ATTO 725 together with ATTO 740, are fluorescent labels for the near infrared spectral region. Their fluorescence is excited most efficiently in the range 700 - 745 nm and 720 - 755 nm, respectively.
• ATTO 725 shows strong absorption and fluorescence. It can be excited with long-wavelength diode lasers.
• ATTO 740 is another of our new near-infrared emitting fluorophores. Its features are strong absorption and acceptable fluorescence