What is the difference between LGC, Biosearch Technologies' Quasar dyes and the Cy dyes?

The Quasar™ dyes may be used as direct replacements for the Cy™ dyes and are anticipated to perform equivalently to their Cy dye counterparts. They share the same chromophore structure and spectral properties, differing principally in their linkage chemistry. Quasar 570 replaces Cy3, Quasar 670 replaces Cy5 and Quasar 705 replaces Cy5.5 dye. Quasar dyes are slightly more hydrophobic and therefore soluble in the reagents of DNA synthesis. Importantly, the Quasar dyes are available as amidites and may be incorporated during oligonucleotide synthesis, thus avoiding the post-synthesis dye conjugation required with Cyanine dyes.