CYANINFARBSTOFFE ALS MARKIERAGENZIEN

Disclosed are cyanine dyes that are useful for labelling and detecting biological and other materials. The dyes are of formula (I): in which groups R 3 and R 4 are attached to the Z 1 ring structure and groups R 5 and R 6 are attached to the Z 2 ring structure, and n = 1, 2 or 3; Z 1 and Z 2 independently represent the carbon atoms necessary to complete a one ring, or two-fused ring aromatic system; at least one of groups R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and R 7 is the group -E-F where E is a single bond or a spacer group and F is a target bonding group; one or more of groups R 11 , R 12 , R 13 and R 14 are independently selected from the group -(CH 2 ) k -W, where W is sulphonic acid or phosphonic acid and k is an integer from 1 to 10. The dyes may be used in fluorescence labelling applications, where the presence of one and preferably multiple water solubilising groups attached to the 3-position of the indolinium ring reduces dye-dye interactions, and hence dye-dye quenching, particularly where multiple dye molecules are attached to components such as nucleic acids, oligonucleotides, proteins and antibodies.