ATTO 655 represents a new generation of fluorescent labels with strong absorption, high fluorescence quantum yield, excellent thermal and photo-stability, exceptional resistance to atmospheric ozone, and very good water solubility. These properties make it highly suitable for single-molecule detection, flow cytometry (FACS) and fluorescence in-situ hybridization (FISH), among others.
ATTO 655 is a zwitterionic dye, meaning that once it is coupled to a substrate, the dye molecule becomes electrically neutral. It is a strong electron acceptor, and its fluorescence is effectively quenched by electron donors such as guanine or tryptophan. The optimal excitation range for ATTO 655 is between 640 and 660 nm, with suitable excitation sources including the 647 nm line of a Krypton-Ion laser or a diode laser emitting at 650 nm.
Atto 655 (Figure 1) can be used as an alternative of Alexa Fluor®660.
Figure 1. Structure of 5'-Atto 655 (R = sequence).
metabion offers the Atto 655 modification in its DNA and RNA portfolio (as a 5'-, 3'- or internal Atto 655-dT modification):